1. Many factors affect the rate of enzyme-catalyzed reactions including substrate concentration, inhibitors, pH, temperature, pressure, and water content.
2. Enzyme activity is highest at its optimal pH and temperature, and decreases significantly above and below these values. It is also affected by the concentrations of inhibitors and activators.
3. Environmental factors like temperature, pressure, and water content can irreversibly denature enzymes and decrease their activity. Careful control of these factors allows for inhibition of undesirable enzyme reactions in food processing and storage.
This document provides an overview of peptides. It defines peptides as short chains of amino acids linked by peptide bonds. Peptides are distinguished from proteins based on their smaller size, typically containing fewer than 50 amino acid units. The document discusses peptide bond formation, characteristics of peptide bonds, classes of peptides, physical properties, examples of individual peptides, food-derived peptides with biological activity, and applications of peptides in molecular biology.
This document discusses protein reactions that occur during food processing. It covers both enzyme-catalyzed and chemical reactions that proteins undergo, including proteolytic enzymes like serine and cysteine endopeptidases. Specific modifications are described, such as the Maillard reaction and changes induced by heat, pH, oxidation. Controlling these reactions through processing conditions and enzymes is important for food properties and safety.
This document discusses the physico-chemical properties of proteins, including their physical and chemical properties. It describes proteins' ability to dissociate depending on pH, their optical activity, solubility which depends on factors like pH and salt concentration, and their ability to form foams and stabilize foams through adsorption at gas-liquid interfaces. It also discusses proteins' hydration, swelling power in water, and ability to form gels through polymeric networks or aggregate dispersions.
Enzymes have many applications in food processing. Examples include:
1. Glucose oxidase and catalase are used to remove oxygen and glucose from foods to prevent browning and extend shelf life.
2. Amylases are used in brewing and baking to break down starches.
3. Proteinases or peptidases are used in cheese production, meat tenderizing, and improving dough properties.
4. Immobilized enzymes can be reused, making them more economical for continuous processes.
The document discusses the structure of proteins at different levels:
- Primary structure refers to the amino acid sequence in the polypeptide chain. Secondary structure involves hydrogen bonding that forms alpha helices or beta pleated sheets. Tertiary structure describes the overall 3D shape of the folded polypeptide chain. Quaternary structure involves the interactions between multiple polypeptide subunits. The document outlines the forces that stabilize protein structures such as disulfide bonds, hydrogen bonding, and hydrophobic interactions. Proteins are classified based on their composition, which can include modifications like glycoproteins, lipoproteins, or metal-binding groups.
This document discusses reactions of proteins involved in food processing. It describes various enzyme-catalyzed reactions like those involving serine, cysteine, metallo and aspartic endopeptidases. It also discusses chemical and enzymatic modifications of proteins for food processing, including succinylation, reductive methylation, and disulfide bond reduction/reoxidation. The enzymatic plastein reaction is described which joins peptide fragments through peptide bonds. Overall, the document provides an overview of reactions and modifications that can change protein properties for uses in food processing.
Amino acid analysis and peptide mapping Likhith KLIKHITHK1
Amino Acid Analyzer is specifically configured system optimized for analysis of free amino acids.
PURPOSE:
Detection of presence of Amino acid in variety of biological samples, such as
extracellular and intracellular fluids
plant and animal tissues,
broths, and fruits
beverage juices
Detection of presence of hydrolyzed Amino acid, such as found in
protein, collagen, peptides, and processes foods.
Peptide mapping is an identity test for proteins, especially those
obtained by r-DNA technology. Peptide mapping is a comparative procedure because the information obtained, compared to a Reference Standard or Reference Material similarly treated, confirms the primary structure of the protein, is capable of detecting whether alterations in structure have occurred, and demonstrates process consistency and genetic stability. Peptide mapping refers to the identification of proteins using data from intact peptide masses. It is a powerful test that is capable of identifying single amino acid changes resulting from events such as errors in the reading of complementary DNA (cDNA) sequences or point mutations.
This document provides an overview of peptides. It defines peptides as short chains of amino acids linked by peptide bonds. Peptides are distinguished from proteins based on their smaller size, typically containing fewer than 50 amino acid units. The document discusses peptide bond formation, characteristics of peptide bonds, classes of peptides, physical properties, examples of individual peptides, food-derived peptides with biological activity, and applications of peptides in molecular biology.
This document discusses protein reactions that occur during food processing. It covers both enzyme-catalyzed and chemical reactions that proteins undergo, including proteolytic enzymes like serine and cysteine endopeptidases. Specific modifications are described, such as the Maillard reaction and changes induced by heat, pH, oxidation. Controlling these reactions through processing conditions and enzymes is important for food properties and safety.
This document discusses the physico-chemical properties of proteins, including their physical and chemical properties. It describes proteins' ability to dissociate depending on pH, their optical activity, solubility which depends on factors like pH and salt concentration, and their ability to form foams and stabilize foams through adsorption at gas-liquid interfaces. It also discusses proteins' hydration, swelling power in water, and ability to form gels through polymeric networks or aggregate dispersions.
Enzymes have many applications in food processing. Examples include:
1. Glucose oxidase and catalase are used to remove oxygen and glucose from foods to prevent browning and extend shelf life.
2. Amylases are used in brewing and baking to break down starches.
3. Proteinases or peptidases are used in cheese production, meat tenderizing, and improving dough properties.
4. Immobilized enzymes can be reused, making them more economical for continuous processes.
The document discusses the structure of proteins at different levels:
- Primary structure refers to the amino acid sequence in the polypeptide chain. Secondary structure involves hydrogen bonding that forms alpha helices or beta pleated sheets. Tertiary structure describes the overall 3D shape of the folded polypeptide chain. Quaternary structure involves the interactions between multiple polypeptide subunits. The document outlines the forces that stabilize protein structures such as disulfide bonds, hydrogen bonding, and hydrophobic interactions. Proteins are classified based on their composition, which can include modifications like glycoproteins, lipoproteins, or metal-binding groups.
This document discusses reactions of proteins involved in food processing. It describes various enzyme-catalyzed reactions like those involving serine, cysteine, metallo and aspartic endopeptidases. It also discusses chemical and enzymatic modifications of proteins for food processing, including succinylation, reductive methylation, and disulfide bond reduction/reoxidation. The enzymatic plastein reaction is described which joins peptide fragments through peptide bonds. Overall, the document provides an overview of reactions and modifications that can change protein properties for uses in food processing.
Amino acid analysis and peptide mapping Likhith KLIKHITHK1
Amino Acid Analyzer is specifically configured system optimized for analysis of free amino acids.
PURPOSE:
Detection of presence of Amino acid in variety of biological samples, such as
extracellular and intracellular fluids
plant and animal tissues,
broths, and fruits
beverage juices
Detection of presence of hydrolyzed Amino acid, such as found in
protein, collagen, peptides, and processes foods.
Peptide mapping is an identity test for proteins, especially those
obtained by r-DNA technology. Peptide mapping is a comparative procedure because the information obtained, compared to a Reference Standard or Reference Material similarly treated, confirms the primary structure of the protein, is capable of detecting whether alterations in structure have occurred, and demonstrates process consistency and genetic stability. Peptide mapping refers to the identification of proteins using data from intact peptide masses. It is a powerful test that is capable of identifying single amino acid changes resulting from events such as errors in the reading of complementary DNA (cDNA) sequences or point mutations.
Properties of proteins (Chemistry of Proteins (Part - IV)Ashok Katta
This document discusses various properties and reactions of proteins. It describes how proteins between 1-100nm behave as colloids and can sink in water due to their size and mass. It also explains how plasma proteins exert osmotic pressure, with albumin contributing most of the pressure due to its lower molecular weight. The document outlines factors that cause protein denaturation and precipitation, such as heat, acids, salts, metals and solvents. It provides examples of precipitation tests including heat coagulation, half/full salt saturation, and reactions with metals or alkaloids.
This document discusses the properties and characteristics of amino acids. It covers their ionic properties, isoelectric points, optical activity, solubility, UV absorption, and various chemical reactions including esterification, acylation, alkylation, reactions with carbonyl compounds, and reactions involving functional groups like cysteine and methionine. It notes that amino acids are important in developing flavors and aromas in foods during high-temperature cooking methods like frying and baking.
Peptides are short chains of amino acids linked by peptide bonds. They are distinguished from proteins by typically containing fewer than 50 amino acid units. Peptides are formed through condensation reactions between carboxyl and amino groups of separate amino acids, releasing a water molecule. Peptide bonds are rigid and planar, contributing to protein structure stability. Peptides serve many important biological functions and can be classified based on their production method, including through ribosomal translation, nonribosomal synthesis, and enzymatic digestion of proteins in foods. Bioactive peptides derived from food proteins can have beneficial effects like lowering blood pressure, cholesterol, and antimicrobial properties.
This document discusses peptide synthesis methods, including solution phase peptide synthesis and solid phase peptide synthesis (SPPS). SPPS involves attaching the starting peptide to an inert resin bead and performing sequential amino acid couplings and deprotections while the growing peptide remains attached to the resin. This allows for easy purification after each step. Once the full peptide is synthesized, it is cleaved off the resin bead. SPPS allows for faster synthesis of longer peptides up to 70-100 amino acids in length compared to solution phase synthesis. Applications of synthetic peptides include vaccines, hormones, antibiotics, toxins, and enzyme inhibitors.
CHEMISTRY OF PEPTIDES [M.PHARM, M.SC, BSC, B.PHARM]Shikha Popali
THE CHEMISTRY OF PEPTIDES THE DIFFICULT TO COLLECT DATA FOR READERS , THREFORE HERE WE HAVE COLLECTED ALL THE DATA AT A PLACE AND PROVIDED EASIER TO CHEMISTRIANS.
Spps and side reactions in peptide synthesiskavyakaparthi1
The document discusses side reactions that can occur during solid phase peptide synthesis (SPPS). It describes several types of side reactions including proton abstraction, racemization through azlactone formation or direct abstraction, cyclization through diketopiperazine formation, and O-acylation. Racemization is a particular concern in SPPS since it changes the stereochemistry of amino acids. The document outlines factors that influence the likelihood of different side reactions such as the amino acid, solvent, and presence of tertiary amines. Understanding side reactions is important for planning and carrying out efficient SPPS.
The document discusses biotransformation, which refers to chemical alterations of drugs in the body that make them more polar and able to be eliminated. It covers major topics like the phases of biotransformation (Phase I involving reactions like oxidation and Phase II involving conjugation), sites of biotransformation mainly the liver, and classes of drug metabolizing enzymes involved like cytochromes P450. It provides examples of specific enzyme reactions and drug substrates. Overall it serves as a comprehensive overview of the process of biotransformation in the body.
Polypeptides,peptides, types of peptides, structure of dipeptide, tripeptide...ShwetaMishra115
Descriptive notes on polypeptides
Polypeptides,peptides, types of peptides, structure of dipeptide, tripeptide and oligopeptide and different functions of peptide
Quantitative estimation of protein Likhith KLIKHITHK1
This document provides information about quantitatively estimating the amount of proteins in a sample. It discusses several common methods for protein quantification, including the Lowry method, Bradford method, Biuret method, and Bicinchoninic Acid (BCA) method. For the Lowry and Bradford methods, it provides details on the principles, reagents used, and procedures for making standard curves and estimating protein concentration in an unknown sample. The document emphasizes that accurate protein quantification is important for protein studies in research.
A presentation discussing amino acids, peptide bonds and peptide synthesis. The Merrifield Synthesis of Peptides is further discussed covering principle, methodology, isolation and purification, its advantages and disadvantages. A brief note on protecting groups is mentioned. A few practical applications of synthetic peptides are mentioned and discussed in brief as well.
1) The document discusses coenzymes and vitamins, which are organic molecules that serve as cofactors for enzyme reactions in the body. It covers various coenzymes like ATP, NAD+, FAD, and FMN that are derived from vitamins and transport chemical groups between enzymes.
2) Vitamins are classified as either water-soluble or fat-soluble. Water-soluble vitamins include the B vitamins and vitamin C, while fat-soluble vitamins are vitamins A, D, E, and K. Vitamins function as coenzymes and are essential for growth, development and various metabolic processes.
3) The document provides details on the structures and functions of important coen
Drug metabolism involves the chemical modification of drugs inside the body through enzymatic reactions. There are two main phases - in Phase I, functional groups are introduced onto the drug molecule through reactions like oxidation, reduction and hydrolysis, making the drug more polar and able to be eliminated. In Phase II, polar groups are conjugated onto the drug, like glucuronidation or sulfation, which allows the drug to be more readily excreted from the body. The major sites of drug metabolism are the liver, small intestine and kidneys, and it occurs through cytochrome P450 enzymes in the endoplasmic reticulum and cytosol of cells.
This document discusses proteins and amino acids. It defines proteins as large biomolecules composed of chains of amino acids that are essential to life processes. The 20 standard amino acids are the building blocks of proteins. They contain an amino group, a carboxyl group, a hydrogen atom, and a variable side chain that determines each amino acid's properties. Proteins have primary, secondary, tertiary, and quaternary structures that give them their final 3D shapes and functions in the body.
1. Vitamins are organic molecules that serve as cofactors for enzyme reactions and must be obtained through diet as they cannot be synthesized by the body.
2. Vitamins are classified as either water-soluble or fat-soluble, with water-soluble vitamins including all B vitamins and vitamin C, and fat-soluble vitamins being vitamins A, D, E, and K.
3. Each vitamin has a specific biochemical function, such as vitamin C serving as an antioxidant and cofactor for collagen synthesis, vitamin B12 acting as a cofactor for fatty acid and amino acid metabolism, and vitamin K being required for blood clotting through gamma-carboxylation of glutamate residues.
This document provides an overview of drug metabolism and biotransformation. It defines biotransformation as the biochemical alteration of drugs or xenobiotics by enzymes. The liver is identified as the major site of biotransformation. Drug metabolism occurs in two phases - phase I involves reactions like oxidation, reduction and hydrolysis. Phase II involves conjugating reactions. Factors like enzyme induction and inhibition can influence the extent of drug metabolism. Cytochrome P450 enzymes and phase I and II enzymes involved in biotransformation are also discussed.
Protein Structure, Protein Denaturation, Taq PolymeraseMd. Eleas Kobir
The document discusses the structure of proteins at four levels - primary, secondary, tertiary, and quaternary. The primary structure is the sequence of amino acids in the protein chain. Secondary structure involves alpha helices and beta sheets formed by hydrogen bonding between amino acids. Tertiary structure describes the complete three-dimensional folding of the protein. Quaternary structure refers to the association of two or more protein subunits. Taq polymerase is used in PCR because it is heat-stable and allows DNA amplification without needing to add new enzyme during each cycle. Protein denaturation occurs when proteins lose their structure due to extreme conditions like heat, acids, salts, etc. and can disrupt protein function.
The document discusses various Phase II biotransformation reactions. It describes conjugation reactions like conjugation with glucuronic acid, sulphate moieties, alpha amino acids, and glutathione. Conjugation with glucuronic acid is the most common reaction where glucuronic acid is attached to form glucuronides. Conjugation with sulphate occurs less frequently. Amino acid conjugation forms amide bonds between carboxylic acids and amino acids like glycine. These conjugation reactions make compounds more polar and water soluble for excretion.
Biotransformation involves the chemical alteration of drugs in the body through phase 1 and phase 2 reactions. Phase 1 reactions like oxidation, reduction and hydrolysis activate or expose functional groups on drugs. Phase 2 reactions like conjugation make drugs more polar and excretable. The liver is the primary site of biotransformation through cytochrome P450 enzymes and UDP-glucuronyltransferases. First pass metabolism can decrease oral bioavailability. Drug interactions can occur through enzyme induction, increasing metabolism of other drugs, or enzyme inhibition, decreasing metabolism of other drugs.
La Superintendencia de Industria y Comercio de Colombia formuló cargos contra GENOMMA LAB y sometió toda su publicidad a control preventivo por publicidad engañosa en varios de sus productos. También ratificó una sanción por más de $277 millones de pesos contra KOKORIKO por publicidad engañosa en su promoción "La Picada Mundialista". Estas decisiones buscan proteger a los consumidores, especialmente los de menores ingresos, de información publicitaria engañosa.
1) The document discusses food proteins and enzymes, their importance in biological systems, and their various functions and sources.
2) Proteins are made up of amino acids and play many critical roles including as enzymes, hormones, antibodies, and structural components.
3) The document covers the classification of amino acids, sources of food proteins like meat and dairy, and the roles of enzymes in catalyzing biochemical reactions.
GFS Chemicals Karl Fischer Reagents - Watermark BrandLiza Tallon
This document provides an overview of GFS Chemicals' Watermark Karl Fischer reagent product line. It describes their pyridine-free single and two-component volumetric reagents as well as their coulometric reagents. It also lists their water standards and solvents for applications such as ketone and aldehyde analysis. GFS Chemicals aims to offer comprehensive and innovative Karl Fischer solutions to meet customers' varying analytical needs.
Properties of proteins (Chemistry of Proteins (Part - IV)Ashok Katta
This document discusses various properties and reactions of proteins. It describes how proteins between 1-100nm behave as colloids and can sink in water due to their size and mass. It also explains how plasma proteins exert osmotic pressure, with albumin contributing most of the pressure due to its lower molecular weight. The document outlines factors that cause protein denaturation and precipitation, such as heat, acids, salts, metals and solvents. It provides examples of precipitation tests including heat coagulation, half/full salt saturation, and reactions with metals or alkaloids.
This document discusses the properties and characteristics of amino acids. It covers their ionic properties, isoelectric points, optical activity, solubility, UV absorption, and various chemical reactions including esterification, acylation, alkylation, reactions with carbonyl compounds, and reactions involving functional groups like cysteine and methionine. It notes that amino acids are important in developing flavors and aromas in foods during high-temperature cooking methods like frying and baking.
Peptides are short chains of amino acids linked by peptide bonds. They are distinguished from proteins by typically containing fewer than 50 amino acid units. Peptides are formed through condensation reactions between carboxyl and amino groups of separate amino acids, releasing a water molecule. Peptide bonds are rigid and planar, contributing to protein structure stability. Peptides serve many important biological functions and can be classified based on their production method, including through ribosomal translation, nonribosomal synthesis, and enzymatic digestion of proteins in foods. Bioactive peptides derived from food proteins can have beneficial effects like lowering blood pressure, cholesterol, and antimicrobial properties.
This document discusses peptide synthesis methods, including solution phase peptide synthesis and solid phase peptide synthesis (SPPS). SPPS involves attaching the starting peptide to an inert resin bead and performing sequential amino acid couplings and deprotections while the growing peptide remains attached to the resin. This allows for easy purification after each step. Once the full peptide is synthesized, it is cleaved off the resin bead. SPPS allows for faster synthesis of longer peptides up to 70-100 amino acids in length compared to solution phase synthesis. Applications of synthetic peptides include vaccines, hormones, antibiotics, toxins, and enzyme inhibitors.
CHEMISTRY OF PEPTIDES [M.PHARM, M.SC, BSC, B.PHARM]Shikha Popali
THE CHEMISTRY OF PEPTIDES THE DIFFICULT TO COLLECT DATA FOR READERS , THREFORE HERE WE HAVE COLLECTED ALL THE DATA AT A PLACE AND PROVIDED EASIER TO CHEMISTRIANS.
Spps and side reactions in peptide synthesiskavyakaparthi1
The document discusses side reactions that can occur during solid phase peptide synthesis (SPPS). It describes several types of side reactions including proton abstraction, racemization through azlactone formation or direct abstraction, cyclization through diketopiperazine formation, and O-acylation. Racemization is a particular concern in SPPS since it changes the stereochemistry of amino acids. The document outlines factors that influence the likelihood of different side reactions such as the amino acid, solvent, and presence of tertiary amines. Understanding side reactions is important for planning and carrying out efficient SPPS.
The document discusses biotransformation, which refers to chemical alterations of drugs in the body that make them more polar and able to be eliminated. It covers major topics like the phases of biotransformation (Phase I involving reactions like oxidation and Phase II involving conjugation), sites of biotransformation mainly the liver, and classes of drug metabolizing enzymes involved like cytochromes P450. It provides examples of specific enzyme reactions and drug substrates. Overall it serves as a comprehensive overview of the process of biotransformation in the body.
Polypeptides,peptides, types of peptides, structure of dipeptide, tripeptide...ShwetaMishra115
Descriptive notes on polypeptides
Polypeptides,peptides, types of peptides, structure of dipeptide, tripeptide and oligopeptide and different functions of peptide
Quantitative estimation of protein Likhith KLIKHITHK1
This document provides information about quantitatively estimating the amount of proteins in a sample. It discusses several common methods for protein quantification, including the Lowry method, Bradford method, Biuret method, and Bicinchoninic Acid (BCA) method. For the Lowry and Bradford methods, it provides details on the principles, reagents used, and procedures for making standard curves and estimating protein concentration in an unknown sample. The document emphasizes that accurate protein quantification is important for protein studies in research.
A presentation discussing amino acids, peptide bonds and peptide synthesis. The Merrifield Synthesis of Peptides is further discussed covering principle, methodology, isolation and purification, its advantages and disadvantages. A brief note on protecting groups is mentioned. A few practical applications of synthetic peptides are mentioned and discussed in brief as well.
1) The document discusses coenzymes and vitamins, which are organic molecules that serve as cofactors for enzyme reactions in the body. It covers various coenzymes like ATP, NAD+, FAD, and FMN that are derived from vitamins and transport chemical groups between enzymes.
2) Vitamins are classified as either water-soluble or fat-soluble. Water-soluble vitamins include the B vitamins and vitamin C, while fat-soluble vitamins are vitamins A, D, E, and K. Vitamins function as coenzymes and are essential for growth, development and various metabolic processes.
3) The document provides details on the structures and functions of important coen
Drug metabolism involves the chemical modification of drugs inside the body through enzymatic reactions. There are two main phases - in Phase I, functional groups are introduced onto the drug molecule through reactions like oxidation, reduction and hydrolysis, making the drug more polar and able to be eliminated. In Phase II, polar groups are conjugated onto the drug, like glucuronidation or sulfation, which allows the drug to be more readily excreted from the body. The major sites of drug metabolism are the liver, small intestine and kidneys, and it occurs through cytochrome P450 enzymes in the endoplasmic reticulum and cytosol of cells.
This document discusses proteins and amino acids. It defines proteins as large biomolecules composed of chains of amino acids that are essential to life processes. The 20 standard amino acids are the building blocks of proteins. They contain an amino group, a carboxyl group, a hydrogen atom, and a variable side chain that determines each amino acid's properties. Proteins have primary, secondary, tertiary, and quaternary structures that give them their final 3D shapes and functions in the body.
1. Vitamins are organic molecules that serve as cofactors for enzyme reactions and must be obtained through diet as they cannot be synthesized by the body.
2. Vitamins are classified as either water-soluble or fat-soluble, with water-soluble vitamins including all B vitamins and vitamin C, and fat-soluble vitamins being vitamins A, D, E, and K.
3. Each vitamin has a specific biochemical function, such as vitamin C serving as an antioxidant and cofactor for collagen synthesis, vitamin B12 acting as a cofactor for fatty acid and amino acid metabolism, and vitamin K being required for blood clotting through gamma-carboxylation of glutamate residues.
This document provides an overview of drug metabolism and biotransformation. It defines biotransformation as the biochemical alteration of drugs or xenobiotics by enzymes. The liver is identified as the major site of biotransformation. Drug metabolism occurs in two phases - phase I involves reactions like oxidation, reduction and hydrolysis. Phase II involves conjugating reactions. Factors like enzyme induction and inhibition can influence the extent of drug metabolism. Cytochrome P450 enzymes and phase I and II enzymes involved in biotransformation are also discussed.
Protein Structure, Protein Denaturation, Taq PolymeraseMd. Eleas Kobir
The document discusses the structure of proteins at four levels - primary, secondary, tertiary, and quaternary. The primary structure is the sequence of amino acids in the protein chain. Secondary structure involves alpha helices and beta sheets formed by hydrogen bonding between amino acids. Tertiary structure describes the complete three-dimensional folding of the protein. Quaternary structure refers to the association of two or more protein subunits. Taq polymerase is used in PCR because it is heat-stable and allows DNA amplification without needing to add new enzyme during each cycle. Protein denaturation occurs when proteins lose their structure due to extreme conditions like heat, acids, salts, etc. and can disrupt protein function.
The document discusses various Phase II biotransformation reactions. It describes conjugation reactions like conjugation with glucuronic acid, sulphate moieties, alpha amino acids, and glutathione. Conjugation with glucuronic acid is the most common reaction where glucuronic acid is attached to form glucuronides. Conjugation with sulphate occurs less frequently. Amino acid conjugation forms amide bonds between carboxylic acids and amino acids like glycine. These conjugation reactions make compounds more polar and water soluble for excretion.
Biotransformation involves the chemical alteration of drugs in the body through phase 1 and phase 2 reactions. Phase 1 reactions like oxidation, reduction and hydrolysis activate or expose functional groups on drugs. Phase 2 reactions like conjugation make drugs more polar and excretable. The liver is the primary site of biotransformation through cytochrome P450 enzymes and UDP-glucuronyltransferases. First pass metabolism can decrease oral bioavailability. Drug interactions can occur through enzyme induction, increasing metabolism of other drugs, or enzyme inhibition, decreasing metabolism of other drugs.
La Superintendencia de Industria y Comercio de Colombia formuló cargos contra GENOMMA LAB y sometió toda su publicidad a control preventivo por publicidad engañosa en varios de sus productos. También ratificó una sanción por más de $277 millones de pesos contra KOKORIKO por publicidad engañosa en su promoción "La Picada Mundialista". Estas decisiones buscan proteger a los consumidores, especialmente los de menores ingresos, de información publicitaria engañosa.
1) The document discusses food proteins and enzymes, their importance in biological systems, and their various functions and sources.
2) Proteins are made up of amino acids and play many critical roles including as enzymes, hormones, antibodies, and structural components.
3) The document covers the classification of amino acids, sources of food proteins like meat and dairy, and the roles of enzymes in catalyzing biochemical reactions.
GFS Chemicals Karl Fischer Reagents - Watermark BrandLiza Tallon
This document provides an overview of GFS Chemicals' Watermark Karl Fischer reagent product line. It describes their pyridine-free single and two-component volumetric reagents as well as their coulometric reagents. It also lists their water standards and solvents for applications such as ketone and aldehyde analysis. GFS Chemicals aims to offer comprehensive and innovative Karl Fischer solutions to meet customers' varying analytical needs.
Copper and its alloys like bronze and brass are highly versatile materials used in construction, electronics, transportation, and machine tools. Copper alloys can be cut, formed, bent and joined through various fabrication techniques. The main types of bronze are copper alloys with tin, while brass alloys are copper mixed with zinc. Proper handling and cleaning of copper alloy sheets is required to prevent scratches and corrosion.
El documento resume las propiedades del amoníaco, incluyendo que es un gas incoloro compuesto de nitrógeno e hidrógeno con la fórmula química NH3. Explica que en altas concentraciones puede irritar las vías respiratorias y la piel, e incluso destruir la mucosa gástrica si se ingiere. Finalmente, detalla algunas aplicaciones del amoníaco como limpiador de tejidos, ropa y superficies para eliminar manchas.
El ultrasonido tiene muchas aplicaciones en campos como la medicina, biología, física y química. En medicina, se usa para diagnóstico a través de ecografías y para terapia como la litotricia para destruir cálculos. En la industria, los ultrasonidos de baja intensidad se usan para detección de fallas y los de alta intensidad para limpieza, mientras que los de muy alta intensidad sirven para soldaduras. En ingeniería mecánica, detectan fallas en rodamientos y verifican el estado de material
King Arthur Self Storage is a facility located in West Valley, Utah that has over 500 storage units available for rent, including climate controlled units. The facility has robust security features like cameras, alarms and on-site management. King Arthur Self Storage also partners with the local police department by providing free storage and training space to help serve and protect the community.
The heat-affected zone (HAZ) is the area of sheet metal that undergoes chemical and structural changes during cutting due to localized melting. It can cause issues like discoloration, increased hardness, reduced strength, and corrosion. The size of the HAZ depends on factors like the material's thermal diffusivity, amount and duration of heat applied, and beam size - with techniques like laser cutting producing the smallest HAZ. Effects of the HAZ need to be considered for consistent bending angles and crowning during forming.
This document discusses various enzymatic analytical methods used for food analysis, including substrate determination, enzyme activity determination, enzyme immunoassay, and polymerase chain reaction. Specifically, it covers:
1) Substrate determination methods like end-point assays that use coupled enzyme reactions to measure food constituents.
2) Determining enzyme activity in food to evaluate quality and optimize processes by measuring reaction rates under controlled conditions.
3) Enzyme immunoassays like ELISA that use antibody-antigen reactions and enzyme-labeled antigens to detect food compounds.
4) Polymerase chain reaction (PCR) which amplifies DNA for sensitive species identification and detecting genetically modified foods. PCR allows analysis of heat-treated foods where proteins
Presentation software can be used to create slide shows or multimedia presentations combining text, graphics, video, and sound. It is commonly used for educational purposes to train or present information, for persuasive reasons like advertising, or for narrative storytelling or entertainment. While effective for communicating information visually, presentation software may not be appropriate if the content is trivial, loses meaning when translated to other mediums, or is best preserved in its original form. The method of delivering the presentation should also be considered once it has been created.
El documento describe la anatomía y fisiología de los órganos reproductivos masculinos y femeninos. Detalla los órganos externos e internos de ambos sexos, incluyendo su estructura, función y papel en la reproducción. Explica los procesos de espermatogénesis, ovogénesis y fecundación, donde millones de espermatozoides buscan fecundar al óvulo femenino para dar origen a un nuevo ser.
The document discusses factors that affect enzyme-catalyzed reactions, including substrate concentration, inhibitors, pH, temperature, and pressure. It explains how the reaction rate depends on substrate and enzyme concentrations and can be influenced by activators and inhibitors. It also describes how each enzyme has an optimal pH range and temperature, and discusses how temperature affects reaction rates, microbial growth rates, and thermal inactivation of enzymes.
This document provides an overview of enzymology for biochemistry students. It discusses the key components and characteristics of enzymes, including their chemical nature, cofactors, and metal ions. Various classes of enzymes are described based on their general functions. Important concepts like enzyme specificity, turnover number, and the roles of coenzymes and cofactors are summarized. The document also covers enzyme nomenclature, classification, and some of the advantages and drawbacks of using enzymes as catalysts. Overall, the document serves as an introductory lesson on the fundamentals of enzymology.
This document discusses enzymes and how various factors affect their activity. It explains that enzymes are proteins that act as biological catalysts, and that their activity is influenced by temperature, pH, substrate and enzyme concentration. The optimum temperature and pH are described as well as how rises or falls from these can impact activity. Isoenzymes, which are variants of the same enzyme found in different tissues, are also covered. The concept of rate-limiting enzymes, which determine the overall rate of a metabolic pathway, is defined.
This document discusses various mechanisms of enzyme regulation that can be exploited for strain improvement in industrial microbiology applications. It describes regulation of enzyme activity through allosteric regulation, covalent modification and feedback inhibition. Regulation of enzyme synthesis is also discussed, including feedback repression and attenuation. Common examples are provided like regulation of lysine production in Corynebacterium glutamicum. Overall, the document analyzes how understanding and manipulating different pathways of enzyme regulation can enhance microbial strain performance in industrial settings.
Chemical modification of enzyme to improve physico-chemical propertiesDebabrata Samanta
This document summarizes a discussion on chemically modifying enzymes to improve their physico-chemical properties. It defines enzymes and describes their physical and chemical properties. Chemical modification involves changing an enzyme's structure or groups to alter its properties. Two main types are group-specific reagents and affinity labels, which target certain amino acid side chains. Chemical modification can provide information on enzyme mechanisms and properties. However, it faces limitations as modifiers may not be absolutely specific and can induce conformational changes.
- Amylase, lipase, proteases added to laundry detergents
- Papain, bromelain added to meat tenderizers
- Lysozyme added to wound dressings
Diagnostic:
- Measuring enzyme levels in blood/urine to detect organ damage
- Measuring enzyme levels in blood to diagnose genetic disorders
Therapeutic:
- Enzyme replacement therapy for genetic disorders
- Enzymes as digestive aids or supplements
Research:
- Enzymes used as reagents in clinical assays and diagnostic kits
So in summary, enzymes play important roles in diagnostics, research, and therapeutics in medicine. Their catalytic properties are exploited for various applications.
Unit 4: Plasma Enzyme tests in diagnosis DrElhamSharif
This document provides an overview of plasma enzyme tests and their use in diagnosis. It discusses factors that affect enzyme reaction rates, the clinical usefulness of measuring serum enzyme levels, and specific enzymes that are useful in diagnosing various disorders, including cardiac, hepatic, bone, muscle, malignancies and acute pancreatitis. The document also covers enzyme kinetics, the advantages and disadvantages of enzyme assays, how enzyme activity is measured and calculated, and the classification of different enzyme types.
This document discusses methods for investigating enzyme kinetics through induced velocity studies. It describes how measuring reaction rates at varying substrate concentrations allows researchers to determine kinetic parameters like Vmax and Km using the Michaelis-Menten equation. Factors like temperature, pH, and substrate concentration that affect reaction rates are also examined. The document concludes that understanding enzyme kinetics has applications in medicine, agriculture, and biotechnology, such as developing new drugs, improving crops, and optimizing biofuel production.
This document provides an overview of enzymes. It discusses that enzymes are protein catalysts that increase the rate of chemical reactions in living cells without changing themselves. The document describes the different components of enzyme molecules, including the protein component called the apoenzyme and various cofactors that can be organic compounds, inorganic ions, or prosthetic groups. It also discusses the active site of enzymes and mechanisms of enzyme action, such as induced fit and lock and key models. Additionally, it covers factors that affect enzyme activity like temperature, pH, substrate concentration, and enzyme concentration. The document summarizes different types of enzyme inhibition including competitive, non-competitive, and uncompetitive inhibition. Finally, it discusses mechanisms of regulating enzyme activity, including controlling enzyme
- Enzymes are protein biocatalysts that increase the rate of chemical reactions without being consumed. They are specific in their action and composed of apoenzyme and coenzyme.
- The active site of an enzyme binds specifically to substrates and contains residues that help hold the substrate. Changes to the active site shape affect enzyme function.
- Factors like temperature, pH, substrate/product concentration, and presence of activators or inhibitors can regulate an enzyme's activity rate. Studying an enzyme's kinetics reveals its catalytic mechanism.
- Regulation allows cells to control metabolic pathways by modulating enzyme activity. Competitive inhibitors bind the active site while non-competitive inhibitors cause conformational changes. I
This document discusses enzymes and their properties and functions. It begins by defining enzymes as proteins that act as biological catalysts to accelerate metabolic reactions within cells. Enzymes have several key properties, including that they are proteins, increase reaction rates, function at low concentrations, and catalyze reactions under moderate conditions. The mechanisms of enzyme action involve the binding of specific substrates to the active site of the enzyme, forming an activated transition state complex with a high energy that readily breaks down into products. Enzyme activity can be affected by various factors such as temperature, pH, activators, and inhibitors.
This powerpoint presentation talks about enzymes, specifically its functions, the different types according to its function, and the definition of enzyme activator and inhibitor. A picture diagram is also included to show the process of enzyme activity and as well as a table differentiating apoenzyme and coenzyme. The different factors that affects the enzyme activity are also explained and lastly, the other uses of enzyme in medicine, food and etc.The content of the powerpoint presentation has undergone a research through internet and the best answers has been selected for better understanding. The resources of all the research made that was in this presentation are acknowledged as shown in the Reference part of the slide.
This document summarizes key concepts about enzymes including:
1) Enzymes work as catalysts to lower the activation energy of biochemical reactions and increase reaction rates. They specifically bind to substrates in their active sites.
2) Environmental factors like temperature and pH can impact enzyme activity by causing enzyme denaturation at extreme levels.
3) Enzyme activity is regulated by various mechanisms including allosteric regulation, covalent modification through phosphorylation, and proteolytic activation of zymogens to active enzymes.
Dr. Naresh Panigrahi discusses enzymes and biochemistry. Some key points:
- Enzymes are proteins that act as catalysts to speed up chemical reactions in cells without being used up in the process. They have high specificity for their substrate.
- Enzyme structure includes an apoenzyme protein portion and often a cofactor like a coenzyme, prosthetic group, or metal ion that is required for catalytic activity.
- Factors like pH, temperature, and inhibitors can impact enzyme activity by altering its structure-function relationship.
- Enzymes are classified based on the type of reaction they catalyze and have unique names and EC numbers in enzyme nomenclature systems
Enzymes are protein catalysts that support biochemical reactions in cells and tissues. They have active sites that substrates must fit into in order to undergo reaction. Enzymes are classified based on their reactions and components. Some require coenzymes like B vitamins or metal ions. Enzyme activity is affected by factors like substrate, enzyme, and product concentration; temperature; pH; and presence of activators or inhibitors. Clinical enzyme tests can indicate tissue damage, such as elevated liver enzymes in hepatitis or muscle enzymes in infarction. Together with other markers, enzymes help diagnose and monitor various conditions.
This document discusses enzymes and their catalytic properties. It begins by explaining that enzymes are protein catalysts that speed up biochemical reactions by lowering their activation energy. It then discusses the chemical nature of enzymes as proteins made of amino acid chains. The document covers several factors that affect enzyme activity, such as temperature, pH, and concentration of enzymes and substrates. It also discusses enzyme specificity and inhibition. Key terms related to enzymes and their reactions are defined.
The document defines key terms related to enzymes including substrate, active site, and cofactors. It describes the lock and key and induced fit models of how enzymes bind to substrates. Environmental factors like temperature, pH, and substrate concentration can affect the rate of enzymatic reactions. Cofactors and coenzymes are required for some enzymatic reactions. Competitive and noncompetitive inhibitors can regulate enzyme activity. Examples are given of enzymatic uses in industry, detergents, food, and diagnosing/treating diseases.
1. Enzymes catalyze metabolic reactions by breaking down nutrients, releasing energy, and generating biomolecules. They form metabolic pathways and are regulated to sense cellular needs.
2. Enzymes display extraordinary catalytic power, accelerating reactions by factors of trillions, and do so with great specificity by recognizing substrates through molecular complementarity. Their activity is optimized over a narrow pH and temperature range.
3. Enzyme activity can be regulated by reversible or irreversible inhibitors that compete or bind elsewhere on the enzyme, reducing its affinity or catalytic rate. Coenzymes and prosthetic groups assist catalytic function when bound to the active site.
This document presents information on biocatalysis and enzyme immobilization. It introduces biocatalysis as using biological systems like enzymes to accelerate chemical reactions. It discusses factors that affect enzyme activity such as concentration, temperature, and pH. It also describes different types of biocatalysts including oxidoreductases, transferases, hydrolases, lyases, and isomerases. The document then explains enzyme immobilization, how it protects enzymes and allows for reuse, and some applications for immobilized enzymes in producing antibiotics, steroids, amino acids, and organic acids.
Enzymes are protein catalysts that accelerate biochemical reactions without being consumed. They achieve this by lowering the activation energy of reactions and stabilizing transition states. Enzymes require cofactors like metal ions or organic coenzymes to function. The active site of an enzyme binds specifically to substrates to catalyze reactions. Many factors influence enzyme activity, such as temperature, pH, substrate and product concentration.
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mô tả các thí nghiệm về đánh giá tác động dòng khí hóa sau đốt
العوامل المؤثرة على التفاعلات الانزيمية
1. االنزيمية التفاعالت على المؤثرة العوامل
Factors affecting Enzyme-Catalyzed
Reactions
Prof. Dr. Mohamed Fawzy Ramadan Hassanien
Zagazig University, Egypt
2. Factors affecting Enzyme-Catalyzed
Reactions
1- Effect of Substrate Concentration
(Single-Substrate Reactions)
2- Effect of Inhibitors
3- Effect of pH
4- Effect of Temperature
5- Effect of Pressure
6- Effect of Water
3. -Enzymes in food can be detected only indirectly by measuring
their catalytic activity and, in this way, differentiated from other
enzymes.
-This is the rationale for acquiring knowledge needed to analyze
the parameters which influence or determine the rate of an
enzyme-catalyzed reaction.
-The reaction rate is dependent on the concentrations of the
components involved in the reaction.
-Here, it means primarily the substrate and the enzyme. Also, the
reaction can be influenced by the presence of activators and
inhibitors.
Finally, the pH, the ionic strength of the reaction medium, the
dielectric constant of the solvent (usually water) and the
temperature exert an effect.
4. 1 Effect of Substrate Concentration
Single-Substrate Reactions
-Let us consider a single-substrate reaction.
-Enzyme E reacts with substrate A to form an intermediary
enzyme-substrate complex, EA.
The complex then forms the product P and releases the free
enzyme:
-In order to determine the catalytic activity of the enzyme, the
decrease in substrate concentration or the increase in product
concentration as a function of time can be measured.
5. 1 Effect of Substrate Concentration
Single-Substrate Reactions
The activity curve obtained has the
following regions:
a) The maximum activity which occurs
for a few msec until an equilibrium is
reached between the rate of enzyme-
substrate formation and rate of
breakdown of this complex.
-Measurements in this pre-steady state
region which provide an insight into the
reaction steps and mechanism of catalysis
are difficult and time consuming.
-Hence, further analysis of the pre-steady
state should be ignored.
Progress of an
enzyme-catalyzed
reaction
6. b) The usual procedure is to measure the enzyme activity when a
steady state has been reached. In the steady state, the
intermediary complex concentration remains constant while the
concentration of the substrate and end product are changing.
C) The reaction rate decreases in this region in spite of an excess of
substrate.
The decrease in the reaction rate can be considered to be result of:
-Enzyme denaturation which can readily occur,
-Decreasing the enzyme concentration in the reaction system, or
the product formed increasingly inhibits enzyme activity or, after
the concentration of the product increases,
-The reverse reaction takes place, converting the product back into
the initial reactant.
7. 2 Effect of Inhibitors
-The catalytic activity of enzymes, in addition to substrate
concentration, is affected by the type and concentration
of inhibitors, i.e. compounds which decrease the rate of
catalysis, and activators, which have the opposite effect.
-Activitors include
-metal ions and
-compounds which are active as prosthetic groups or
which provide stabilization of the enzyme’s conformation
or of the enzyme-substrate complex.
-Inhibitors are found among food constituents.
8. 2 Effect of Inhibitors
-Based on kinetic considerations, inhibitors are divided
into two groups:
inhibitors bound irreversibly to enzyme and
inhibitors bound reversibly to enzyme .
-Proteins which specifically inhibit the activity of certain
peptidases, amylases or β-fructofuranosidase are
examples.
-Furthermore, food contains substances which non-
selectively inhibit a wide spectrum of enzymes.
-Phenolic compounds of food and mustard oil belong to
this group.
9. 2 Effect of Inhibitors
-Food might be contaminated with pesticides, heavy
metal ions and other chemicals from a polluted
environment which can become inhibitors under some
circumstances.
-These possibilities should be taken into account when
enzymatic food analysis is performed.
-Food is usually heat treated to suppress undesired
enzymatic reactions.
-As a rule, no inhibitors are used in food processing.
-An exception is the addition of, for example, SO2 to
inhibit the activity of phenolase.
10. 2 Effect of Inhibitors
-Much data concerning the mechanism of action
of enzyme inhibitors have been published in
recent biochemical research.
These data cover
-the elucidation of the effect of inhibitors on
functional groups of an enzyme,
-the effect of inhibitors on the active site and
-the clarification of the general mechanism
involved in an enzyme catalyzed reaction.
11. 3 Effect of pH on Enzyme Activity
-Each enzyme is active only in a narrow pH range and each has a
pH optimum which is often between pH 5.5 and 7.5 (Table).
-The optimum pH is affected by the type and ionic strength of the
buffer used in the assay.
pH Optima of various enzymes
12. 3 Effect of pH on Enzyme Activity
The reasons for the sensitivity of the enzyme to changes in pH are:
a) Sensitivity is associated with a change in protein structure
leading to irreversible denaturation,
b) The catalytic activity depends on the quantity of electrostatic
charges on the enzyme’s active site generated by the prototropic
groups of the enzyme.
-In addition the ionization of dissociable substrates as affected by
pH can be of importance to the reaction rate.
-However, such effects should be determined separately.
13. 4 Influence of Temperature
-Thermal processes are important factors in the processing and
storage of food because they allow the control of chemical,
enzymatic and microbial changes.
-Undesired changes can be delayed or stopped by refrigerated
storage. Heat treatment may either accelerate desirable chemical or
enzymatic reactions or inhibit undesirable changes by inactivation
of enzymes or microorganisms.
-Temperature and time are two parameters responsible for the
effects of a thermal treatment.
-They should be selected carefully to make sure that all necessary
changes, e. g., killing of pathogens, are guaranteed, but still all
undesired changes such as degradation of vitamins are kept as low
as possible.
-The following table informs about quality deterioration caused by
enzymes which can be eliminated e. g., by thermal inactivation.
15. 4 Influence of Temperature
Temperature Optimum
-Enzyme-catalyzed reactions and the growth of
microorganisms show a so-called temperature
optimum, which is a temperature-dependent
maximum resulting from the overlapping of two
counter effects with significantly different
activation energies:
• increase in reaction or growth rate
• increase in inactivation or killing rate
16. 4 Influence of Temperature
Temperature Optimum
-For starch hydrolysis by microbial α-amylase, the
activation energies were :
• Ea (hydrolysis) = 20 kJ · mol−1
• Ea (inactivation) = 295 kJ · mol−1
-As a consequence of the difference in activation
energies, the rate of enzyme inactivation is faster with
increasing temperature than the rate of enzyme catalysis.
-Based on activation energies for the above example, the
following relative rates are obtained (Table).
-Increasing temperature from 0 to 60 ◦C increases the
hydrolysis rate by a factor of 5, while rate of inactivation
is accelerated by more than 10 powers of ten.
18. Temperature Optimum
-The growth of microorganisms
follows a similar temperature
dependence and can also be
characterized by replacing the
value k by the growth rate and
assuming Ea is the reference
value μ of the temperature for
growth (Figure).
-For maintaining food quality,
detailed knowledge of the
relationship between microbial
growth rate and temperature is
important for optimum
production processes (heating,
cooling, freezing).
Growth rate and temperature for
1) psychrophilic (Vibrio AF-1),
2) mesophilic (E. coli) and
3) thermophilic (Bacillus cereus)
microorganisms
19. Temperature Optimum
-The highly differing activation energies for
killing microorganisms and for normal chemical
reactions have triggered a trend in food
technology towards the use of high-temperature
short-time (HTST) processes in production.
-These are based on the findings that at higher
temperatures the desired killing rate of
microorganisms is higher than the occurrence of
undesired chemical reactions.
20. Thermal Stability
-The thermal stability of enzymes is quite
variable.
-Some enzymes lose their catalytic activity
at lower temperatures, while others are
capable of withstanding (at least for a short
period of time) a stronger thermal
treatment.
-In a few cases enzyme stability is lower at
low temperatures than in the medium
temperature range.
21. Thermal Stability
-Lipase and alkaline
phosphatase in milk are
thermolabile, whereas
acid phosphatase is
relatively stable (Figure).
-Therefore, alkaline
phosphatase is used to
distinguish raw from
pasteurized milk
because its activity is
easier to determine than
that of lipase.
Thermal inactivation of enzymes of milk.
1 Lipase (inactivation extent, 90%),
2 alkaline phosphatase (90%),
3 catalase (80%),
4 xanthine oxidase (90%),
5 peroxidase (90%), and
6 acid phosphatase (99%)
22. Thermal Stability
-Of all the enzymes in the potato tuber (Figure),
peroxidase is the last one to be thermally inactivated.
Thermal inactivation (90%) of enzymes
present in potato tuber
23. Thermal Stability
-Such inactivation patterns are often found among
enzymes in vegetables. In such cases, peroxidase is a
suitable indicator for controlling the total inactivation of
all the enzymes e.g., in assessing the adequacy of a
blanching process.
-However, newer developments aim to limit the enzyme
inactivation to such enzymes responsible for quality
deterioration during storage.
-For example pea seeds in which lipoxygenase is
responsible for spoilage. However, lipoxygenase is more
sensitive than peroxidase, thus a sufficient but gentle
blanching requires the inactivation of lipoxygenase only.
Inactivation of peroxidase is not necessary.
24. 5 Influence of Pressure
-The application of high pressures can inhibit the growth of
microorganisms and the activity of enzymes. This allows the
protection of sensitive nutrients and aroma substances in foods.
-Some products preserved in this gentle way are now in the
market.
-Microorganisms are relatively sensitive to high pressure because
their growth is inhibited at pressures of 300–600 MPa and lower
pH values increase this effect. However, bacterial spores withstand
pressures of >1200 MPa.
-In contrast to thermal treatment, high pressure does not attack
the primary structure of proteins at room temperature. Only H-
bridges, ionic bonds and hydrophobic interactions are disrupted.
Quaternary structures are dissociated into subunits by
comparatively low pressures (<150 MPa).
25. 5 Influence of Pressure
-Higher pressures (>1200 MPa) change the tertiary structure and
very high pressures disrupt the H-bridges which stabilize the
secondary structure.
-The hydration of proteins is also changed by high pressure
because water molecules are pressed into cavities which can exist
in the hydrophobic interior of proteins.
-In general, proteins are irreversibly denatured at room
temperature by the application of pressures above 300 MPa while
lower pressures cause only reversible changes in the protein
structure.
26. 5 Influence of
Pressure
-In the case of enzymes, even
slight changes in the steric
arrangement and mobility of the
amino acid residues which
participate in catalysis can lead to
loss of activity.
-Nevertheless, a relatively high
pressure is often required to
inhibit enzymes. But the pressure
required can be reduced by
increasing the temperature, as
shown in the Figure for α-
amylase.
Pressure-temperature diagram for
the inactivation kinetics of α-
amylase from Bacillus subtilis at
pH 8.6.
27. 5 Influence of Pressure
-While a pressure of 550 MPa is required at 25 ◦C to inactivate
the enzyme, a pressure of only 340 MPa is required at 50 ◦C.
-It is remarkable that enzymes can also be activated by changes in
the conformation of the polypeptide chain, which are initiated
especially by low pressures around 100 MPa.
-In the application of the pressure technique for the production of
stable food, intact tissue, and not isolated enzymes, is exposed to
high pressures.
-Thus, the enzyme activity can increase instead of decreasing when
cells or membranes are disintegrated with the release of enzyme
and/or substrate.
28. 5 Influence of Pressure
-Some examples are presented here to show the pressures
required to inhibit the enzyme activity which can negatively effect
the quality of foods.
−Pectin methylesterase: causes the flocculation of pectic acid in
orange juices and reduces the consistency of tomato products. In
orange juice, irreversible enzyme inactivation reaches 90% at a
pressure of 600 MPa. Even though the enzyme in tomatoes is more
stable, increasing the temperature to 59–60 ◦C causes inactivation
at 400 Mpa and at 100 MPa after the removal of Ca2+ ions.
−Peroxidases: induce undesirable aroma changes in plant foods. In
green beans, enzyme inactivation reached 88% in 10 min after
pressure treatment at 900 MPa. At pressures above 400 MPa (32
◦ C), the activity of this enzyme in oranges fell continuously to 50%.
However, very high pressures increased the activity at 32–60 ◦C.
29. 5 Influence of Pressure
-It is possible that high pressure denatures peroxidase to a
heme(in) catalyst to 50%. However, very high pressures increased
the activity at 32–60 ◦C. It is possible that high pressure
denatures peroxidase to a heme(in) catalyst.
− Lipoxygenase from soybeans.
This enzyme was inactivated in 5 min at pH 8.3 by pressures up
to 750 MPa and temperatures in the range 0–75 ◦C. The pressure
stability was reduced by gassing with CO2 and reducing pH to 5.4.
−Polyphenol oxidases in mushrooms and potatoes require
pressures of 800–900 Mpa for inactivation. The addition of
glutathione (5 mmol/l) increases the pressure sensitivity of the
mushroom enzyme. In this case, the inactivation is obviously
supported by the reduction of disulfide bonds.
30. 6 Influence of
Water
-Up to certain extent,
enzymes need to be hydrated
in order to develop activity.
-Hydration of e.g. lysozyme
was determined by IR and
NMR spectroscopy.
-As can be seen in Table, first
the charged polar groups of
the side chains hydrate,
followed by the uncharged
ones.
Hydration of Lysozyme
31. 6 Influence of Water
-Enzymatic activity starts at a water content of 0.2 g/g
protein, which means even before a monomolecular layer
of the polar groups with water has taken place.
-Increase in hydration resulting in a monomolecular layer of
the whole available enzyme surface at 0.4 g/g protein raises
the activity to a limiting value reached at a water content of
0.9 g/g protein. Here the diffusion of the substrate to the
enzyme’s active site seems to be completely guaranteed.
-For preservation of food it is mandatory to inhibit
enzymatic activity completely if the storage temperature is
below the phase transition temperature.