Enzymes are biological molecules (typically proteins) that significantly speed up the rate of virtually all of the chemical reactions that take place within cells. They are vital for life and serve a wide range of important functions in the body, such as aiding in digestion and metabolism
Inhibitors are chemicals that reduce the rate of the enzymatic reactions,
They are usually specific and work at low concentrations,
They block the enzyme, but they do not usually destroy it,
Many drugs and poisons are inhibitors of enzymes in the nervous system,
Inhibitors of the catalytic activities of enzymes provide both pharmacologic agents and research tools for the study of the mechanism of enzyme action.
The flux of metabolites through metabolic pathways involves
catalysis by numerous enzymes. Active control of homeostasis is achieved by the regulation of only a small number of enzymes.
Inhibitors are chemicals that reduce the rate of the enzymatic reactions,
They are usually specific and work at low concentrations,
They block the enzyme, but they do not usually destroy it,
Many drugs and poisons are inhibitors of enzymes in the nervous system,
Inhibitors of the catalytic activities of enzymes provide both pharmacologic agents and research tools for the study of the mechanism of enzyme action.
The flux of metabolites through metabolic pathways involves
catalysis by numerous enzymes. Active control of homeostasis is achieved by the regulation of only a small number of enzymes.
The rate of a chemical reaction is described by the number of molecules of reactant(s) that are converted into the product(s) in a specified time period.
Numerous factors affect the rate of enzyme-catalyzed reactions.
Mechanism of enzyme action -
An enzyme attracts substrates to its active site, catalyzes the chemical reaction by which products are formed, and then allows the products to dissociate (separate from the enzyme surface). The combination formed by an enzyme and its substrates is called the enzyme–substrate complex.
An enzyme is a substance that acts as a catalyst in living organisms, regulating the rate at which chemical reactions proceed without itself being altered in the process. The biological processes that occur within all living organisms are chemical reactions, and most are regulated by enzymes
This ppt describes the overview of enzyme regulation and Allosterism. Presented since October 23,2017GC at Addis Ababa University, School of Medicine, Department of medical biochemistry.
Enzymalogy Factors affecting enzyme activity and kineticsrohini sane
A comprehensive presentation on Factors affecting enzyme activity & Kinetics of Enzymes for MBBS ,BDS, B Pharm & Biotechnology students to facilitate self- study.
The rate of a chemical reaction is described by the number of molecules of reactant(s) that are converted into the product(s) in a specified time period.
Numerous factors affect the rate of enzyme-catalyzed reactions.
Mechanism of enzyme action -
An enzyme attracts substrates to its active site, catalyzes the chemical reaction by which products are formed, and then allows the products to dissociate (separate from the enzyme surface). The combination formed by an enzyme and its substrates is called the enzyme–substrate complex.
An enzyme is a substance that acts as a catalyst in living organisms, regulating the rate at which chemical reactions proceed without itself being altered in the process. The biological processes that occur within all living organisms are chemical reactions, and most are regulated by enzymes
This ppt describes the overview of enzyme regulation and Allosterism. Presented since October 23,2017GC at Addis Ababa University, School of Medicine, Department of medical biochemistry.
Enzymalogy Factors affecting enzyme activity and kineticsrohini sane
A comprehensive presentation on Factors affecting enzyme activity & Kinetics of Enzymes for MBBS ,BDS, B Pharm & Biotechnology students to facilitate self- study.
Enzymes mechanism of action, their specificity types, active center structure and action, inhibitor types, fisher and Koshlend theory are presented. Enzymes classification, a new class of enzymes discovered recently, detailed explanation of each class reaction types is presented as well
Virus, infectious agent of small size and simple composition that can multiply only in living cells of animals, plants, or bacteria. The name is from a Latin word meaning “slimy liquid” or “poison.”
Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans as a source for tinder, traditional medicine, food, and entheogens, as well as their dangers, such as toxicity or infection.
In the late 16th century several Dutch lens makers designed devices that magnified objects, but in 1609 Galileo Galilei perfected the first device known as a microscope. Dutch spectacle makers Zaccharias Janssen and Hans Lipperhey are noted as the first men to develop the concept of the compound microscope.
In the late 16th century several Dutch lens makers designed devices that magnified objects, but in 1609 Galileo Galilei perfected the first device known as a microscope. Dutch spectacle makers Zaccharias Janssen and Hans Lipperhey are noted as the first men to develop the concept of the compound microscope.
Microbial Spoilage include the contamination of Pharmaceutical products with the microbes which lead to spoilage of the product affecting Drug safety and quality, and is not intended for use. Shortly Microbial Spoilage is defined as deterioration of pharmaceutical products by the contaminant microbe.
In the late 16th century several Dutch lens makers designed devices that magnified objects, but in 1609 Galileo Galilei perfected the first device known as a microscope. Dutch spectacle makers Zaccharias Janssen and Hans Lipperhey are noted as the first men to develop the concept of the compound microscope.
Bacteria are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats
Microbiology is the study of organisms that are usually too small to be seen by the unaided eye; it employs techniques—such as sterilization and the use of culture media—that are required to isolate and grow these microorganisms.
Bacteria have existed from very early in the history of life on Earth. Bacteria fossils discovered in rocks date from at least the Devonian Period (419.2 million to 358.9 million years ago), and there are convincing arguments that bacteria have been present since early Precambrian time, about 3.5 billion years ago.
Bacteria are microscopic, single-celled organisms that thrive in diverse environments. These organisms can live in soil, the ocean and inside the human gut. Humans' relationship with bacteria is complex. Sometimes bacteria lend us a helping hand, such as by curdling milk into yogurt or helping with our digestion
Bacteria are microscopic, single-celled organisms that thrive in diverse environments. These organisms can live in soil, the ocean and inside the human gut. Humans' relationship with bacteria is complex. Sometimes bacteria lend us a helping hand, such as by curdling milk into yogurt or helping with our digestion
Diuretics, also called water pills, are medications designed to increase the amount of water and salt expelled from the body as urine. There are three types of prescription diuretics. They're often prescribed to help treat high blood pressure, but they're used for other conditions as well.
The main site of diuretic action is well established for the different groups of diuretics: carbonic anhydrase inhibitors act on the proximal tubulus, loop diuretics on the diluting segment, thiazides on the cortical diluting segment/distal tubulus, and potassium-sparing agents on distal tubulus/collecting ducts.
Diuretics, also called water pills, are medications designed to increase the amount of water and salt expelled from the body as urine. There are three types of prescription diuretics. They’re often prescribed to help treat high blood pressure, but they’re used for other conditions as well.
Proton-pump inhibitors are a group of medications whose main action is a pronounced and long-lasting reduction of stomach acid production. Within the class of medications, there is no clear evidence that one agent works better than another. They are the most potent inhibitors of acid secretion available.
The main site of diuretic action is well established for the different groups of diuretics: carbonic anhydrase inhibitors act on the proximal tubulus, loop diuretics on the diluting segment, thiazides on the cortical diluting segment/distal tubulus, and potassium-sparing agents on distal tubulus/collecting ducts.
In conclusion, the present study found that esomeprazole 40 mg daily may be more effective than either omeprazole 20 mg daily, pantoprazole 40 mg daily or lansoprazole 30 mg daily for the rapid relief of heartburn symptoms in patients with endoscopically proven reflux esophagitis.
Mechanisms of diuretic drugs. Diuretic drugs increase urine output by the kidney (i.e., promote diuresis). This is accomplished by altering how the kidney handles sodium. If the kidney excretes more sodium, then water excretion will also increase.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
Acute scrotum is a general term referring to an emergency condition affecting the contents or the wall of the scrotum.
There are a number of conditions that present acutely, predominantly with pain and/or swelling
A careful and detailed history and examination, and in some cases, investigations allow differentiation between these diagnoses. A prompt diagnosis is essential as the patient may require urgent surgical intervention
Testicular torsion refers to twisting of the spermatic cord, causing ischaemia of the testicle.
Testicular torsion results from inadequate fixation of the testis to the tunica vaginalis producing ischemia from reduced arterial inflow and venous outflow obstruction.
The prevalence of testicular torsion in adult patients hospitalized with acute scrotal pain is approximately 25 to 50 percent
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
263778731218 Abortion Clinic /Pills In Harare ,sisternakatoto
263778731218 Abortion Clinic /Pills In Harare ,ABORTION WOMEN’S CLINIC +27730423979 IN women clinic we believe that every woman should be able to make choices in her pregnancy. Our job is to provide compassionate care, safety,affordable and confidential services. That’s why we have won the trust from all generations of women all over the world. we use non surgical method(Abortion pills) to terminate…Dr.LISA +27730423979women Clinic is committed to providing the highest quality of obstetrical and gynecological care to women of all ages. Our dedicated staff aim to treat each patient and her health concerns with compassion and respect.Our dedicated group ABORTION WOMEN’S CLINIC +27730423979 IN women clinic we believe that every woman should be able to make choices in her pregnancy. Our job is to provide compassionate care, safety,affordable and confidential services. That’s why we have won the trust from all generations of women all over the world. we use non surgical method(Abortion pills) to terminate…Dr.LISA +27730423979women Clinic is committed to providing the highest quality of obstetrical and gynecological care to women of all ages. Our dedicated staff aim to treat each patient and her health concerns with compassion and respect.Our dedicated group of receptionists, nurses, and physicians have worked together as a teamof receptionists, nurses, and physicians have worked together as a team wwww.lisywomensclinic.co.za/
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
3. Enzymes
There are two fundamental conditions for life. First, the living entity must be able
to self-replicate; second, the organism must be able to catalyze chemical
reactions efficiently and selectively.
Life depends on the existence of powerful and specific catalysts which is known
as enzymes. Almost every biochemical reaction is catalyzed by an enzyme.
• Living procedures are based on chemical reactions and to accelerate
these reactions in cells require specific catalyst. Enzymes are proteins
which perform this function.
• Therefore, enzymes are biocatalyst produced by living cells to catalyze
biochemical reactions. A catalyst accelerate the rate of chemical reactions
but remains chemically unchanged at the end of reaction.
• Enzymes acted upon the metabolite is called the enzyme’s substrate.
• Without Enzyme there is no known live cells in the world
4. Enzymes needed in all the systems of the body, like
in the movement of nutrients for oxidation
in the conversion of energy from foods and
in the synthesis of macromolecules
in Blood circulation system
in the respiration system
in reproduction system
5. • Enzymes are Proteins except rybozyme (RNA Enzyme)
• Enzymes are 3 dimensional structure which is important for its activity
• Molecular weight of most of the enzymes are about 12kD to 1000kD
• Some are pure protein
• Most of the enzyme contains additional chemical structures other than
proteins, which are called cofactors
Enzyme Hormone
Absolutely protein in nature May be other than protein, eg, steroid
Act at the site of production Usually act distant to the site of
production
Transportation to the site of action
not via blood
Transportation to the target cell via blood
Shows catalytic activity Shows regulatory activity
6. 1. Active sites: Enzyme molecules contain a special pocket or cleft called
the active site. The active site contains amino acid side chains that create
a three dimentional surface complementary to the substrate. The active
site binds the substrate, forming the enzyme-substrate (ES) complex. ES
is converted to an Enzyme-Product (EP) complex that subsquently
dissociates to enzyme and product.
2. Catalytic efficiency: Enzymes are excellent catalysts, speeding up
reactions 105 to 1017 fold. They speed up reactions without being used up.
Typically each enzyme molecule capable to transfer 100-1000 substrate
molecules into product in each second.
3. Specificity: Enzymes are highly specific, interacting with one or few
substrates and catalyzing only one type of chemical reactions.
Since enzymes are extremely selective for their substrates, the set of
enzymes presence in a organelle of the cell determines which metabolic
pathways occur in that portion of the cell.
Fundamental Properties of Enzyme
7.
8. 4. Regulation– Enzymes can be activated or inhibited, so that the
rate of product formation responds to the needs of the cell.
Some enzymes can be regulate metabolic signals.
5. Location within the cell: Many enzymes are localized in specific
organells within the cell. Such compartmentalization serves to
isolate the reaction substrate or product from other competing
reactions. This provides a favorable environment for the reaction
and organizes the thousands of enzymes present in the cell into
purposeful pathway.
9. 6. Holoenzyme:
In many cases, the enzyme consists of the protein and a combination of
one or more non-protein parts called cofactors. This enzyme complex is
usually simply referred as the holoenzyme.
Apoenzyme: The polypeptide or protein part of the enzyme is called the
apoenzyme and may be inactive in its original synthesized structure. The
inactive form of the apoenzyme is known as a proenzyme or zymogen.
The proenzyme may contain several extra amino acids in the protein
which are removed, and allows the final specific tertiary structure to be
an activated apoenzyme form.
10. Cofactors:
A cofactor is a non-protein substance which may be organic, and called
a coenzyme. The coenzyme is often derived from a vitamin.
Thiamine, B6, B12, NAD, FAD, Coenzyme A (CoA)
Another type of cofactor is an inorganic metal ion called a metal ion
activator. The inorganic metal ions may be bonded through coordinate
covalent bonds. The major reason for the nutritional requirement for
minerals is to supply such metal ions as Zn+2, Mg+2, Mn+2, Fe+2, Cu+2, K+1,
and Na+1 for use in enzymes as cofactors.
11. No Class Type of reaction catalyzed Examples
1 Oxidoreductases Transfer of electrons (hydride ions or H atoms) Dehydrogenases,
Oxidases
2 Transferases Group transfer reactions Transaminase,
kinases
3 Hydrolases Hydrolysis reactions (transfer of functional
groups to water)
Estrases,
Digestive
enzymes
4 Lyases Addition of groups to double bonds, or
formation of double bonds by removal of
groups
Decarboxylases,
Aldolases
5 Isomerases Transfer of groups within molecules to yield
isomeric forms
Fumerase, hexo-
isomerase
6 Ligases Formation of C-C, C-S, C-O, and C-N bonds by
condensation reactions
Citric acid
synthase
Classification of Enzymes
12. Enzyme Nomenclature
Recommended name:
The different kinds of enzymes are named in different ways:
• Most often enzymes are named by adding a suffix 'ase' to the root
word of the substrate. For example, Lipase (fat hydrolysing enzyme),
Sucrase (breaking down sucrose).
• Sometimes the enzymes are named on the basis of the reaction that
they catalyse. For example, Polymerase (aids in polymerisation),
Dehydrogenase (removal of H atoms).
• Some enzymes have been named based on the source from which
they were first identified. For example, Papayin from papaya.
• The names of some enzymes ends with an 'in' indicating that they
are basically proteins. For example, Pepsin, Trypsin etc.
Each enzyme has assigned for two names. The first one is it’s short,
recommended name, convenient for everyday use. The second is the
more complete systematic name, which is used when an enzyme must be
identified without ambiguity.
13. Systematic name:
IUBMB (International Union for Biochemistry and Molecular Biology)
developed a system of nemenclature in which enzymes are classified into
six major classes, each with numerous subgroup. The systematic names
are unambiguous and informative but are frequently too cumbersome to
be of general use.
14. • Six main enzyme groups are:
• EC 1 - Oxidoreductases
• EC 2 - Transferases
• EC 3 - Hydrolases
• EC 4 - Lyases
• EC 5 - Isomerases
• EC 6 - Ligases
• Enzymes are named and classified depending on the reaction
they catalyse.
• An EC number represents the reaction catalyzed by an enzyme
(protein) but not the enzyme (protein) itself. Therefore different
proteins can have the same EC number.
EC, Enzyme Commission
15. Example: (Glucose phosphotransferase, Hexokinase)
– E.C. Number: 2.7.1.1
• 2: transferase
• 7: subclass (phosphotransferase)
• 1: phosphotransferase with a hydroxyl group as acceptor
• 1: D-glucose as phosphoryl group acceptor
ATP + D-Glucose ADP + D-Glucose 6-phosphate
Hexokinase
17. Factors afecting reaction velocity:
Enzymes can be isolated from cells and their
properties studied in vitro.
Velocity: The rate or velocity of a reaction is the
number of substrate molecules converted to
product per unit time, velocity is usually
expressed as µmol of product formed per
minute.
Factors affecting reaction velocity:
1. Substrate concentration:
The rate of an enzyme-catalyzed reaction
increases with increasing substrate
concentration until a maximal velocity is
reached. The plot of initial reaction velocity
against substrate concentration is hyperbolic.
[S]
Rate
18. 2. Temperature:
The reaction velocity increases with temperature until a peak velocity is
reached, and further elevation of the temperature results in a decrease in
reaction velocity because of the temperature-induced denaturation of the
enzyme.
Optimum temperature of human enzyme : 35-40°C
>40°C denaturation starts
Thermipholic bacteria in hot spring can survive at approx 70°C
Relationship of velocity to enzyme concentrations: The rate of the
reaction is directly proportional to the enzyme concentration at all substrate
concentrations. For example, if the enzyme concentration is reduceed by
50%, the initial rate of reaction (V0), as well as that of Vmax are reduced to
half of the original.
19. 3. pH (acid-base property):
[H+] affects reaction velocity
The catalytic process usually requires specific chemical groups (ionized or un-
ionized) in enzyme or substrate in order to interact.
eg, if a catalytic activity requires an amino group of an enzyme to be a
protonated form (-NH3
+), at alkaline pH this group is deprotonated and
therefore the reaction velocity declines.
Extremes of pH may leads to denaturation of the enzyme because the
structure of the catalytically active protein molecule depends on the ionic
character of the amino acid side chains.
Optimum pH varies for different enzymes: eg pepsin (digestive enzyme in
stomach) maximally active at pH 2.0, whereas enzymes, supposed to work at
neutral pH are denatured by such an acidic environment.
20. Reaction Rates and the Transition State
Enzymes speed up reactions enormously.
To understand how they do this, examine the concepts
of activation energy & the transition state.
In order to react, the molecules involved are forced to
have an unlikely electronic arrangement
To proceed the reactions the molecules must pass
through a high energy state.
21. This high energy state is called the transition state.
The energy required to achieve the transition state for
one mol of the substrate is called the activation
energy for the reaction.
The higher the activation
energy for the transition
barrier, the slower the
reaction rate.
22. Enzymes lower energy
barrier by forcing the
reacting molecules
through a different
transition state.
This transition state
Involves interactions
with the enzyme.
Enzyme
23. Enzyme Kinetics
Kinetics Kinetics refers to the rate of change in a
biochemical (or other) reaction i.e. the study of reaction rates.
Kinetic comes from the Greek word "kinesis" which means
motion.
Enzyme Kinetics Rate of chemical reactions mediated by
enzymes. Enzymes can increase reaction rate by favoring or
enabling a different reaction pathway with a lower activation
energy, making it easier for the reaction to occur.
24. Michaelis-Menten Model or Equation
k1 k3
E + S E●S E+ P
k2
From this kinetic scheme, a relationship can be
derived for the rate or velocity of the reaction:
Michaelis-Menten Equation
Vmax[S]
[S] + Km
V =
25. v or
rate
[S]
Vmax
Km
½ Vmax
0
Vmax, the maximum rate (plateau)
is k3 x [total enzyme]
Km =(k1 + k3)/ k2, almost a
binding constant
Michaelis-Menten constant
(Km) can be defined as the
concentration of the specific
substrate at which a given
enzyme reaches one-half its
maximum velocity.
Km = [S], where the velocity v
= ½ Vmax,
Km is called the Michaelis
constant.
k1 k3
E + S E●S E+ P
k2
26. Km reflects the affinity of the
enzyme for a substrate.
•Low Km value reflects a high affinity
of the enzyme for substrate,
because a low concentration of
substrate is needed to half-saturate
the enzyme that is to reach the
velocity at ½ Vmax.
•High Km reflects the low affinity
enzyme for substrate because a
high concentration of substrate is
needed to half-saturate the enzyme.
v
Vmax/2
Km
[S]
Vmax
27. Lineweaver-Burk plot:
This form of the Michaelis-Menten equation is
called the Lineweaver-Burk equation. For
enzymes obeying the Michaelis-Menten
relationship, a plot of 1/V0 versus 1/[S] yields a
straight line. This line has a slope of Km/Vmax, an
intercept of 1/Vmax on the 1/V0 axis, and an
intercept of 1/Km on the 1/[S] axis. The double-
reciprocal presentation, also called a Lineweaver-
Burk plot, has the great advantage of allowing a
more accurate determination of Vmax, which can
only be approximated from a simple plot of V0
versus [S].
28. Each enzyme has a characteristic Km for a given substrate
Enzyme Substrate Km, mM
Catalase H2O2 25
Hexokinase ATP 0.4
D-Glucose 0.05
D-Fructose 1.5
-Galactosidase D-Lactose 4.0
Threonine dehydratase L-Threonine 5.0
29. Enzyme measurement:
Unit: One unit of enzyme activity is defined as that amount
causing transformation of 1µmole of substrate to product per
minute at 25°C under optimal conditions of measurement.
Unit of enzyme is expressed as μmoles/min/mg protein
Specific activity:
The specific activity is the number of enzyme units per mg of
protein. The specific activity is a measure of enzyme purity.
30. Inhibition of Enzyme activity
• Substance that can diminish the velocity of an enzyme-catalyzed
reaction is called an inhibitor.
Two types of Enzyme Inhibition:
• Reversible inhibitors bind to enzymes through non-covalent
bonds, thus dilution of the enzyme-inhibitor complex results in
dissociation of the reversibly bound inhibitor.
• Irreversible inhibitors bind to enzymes through covalent bonds.
Reversible inhibition:
Competitive inhibition, Noncompetitive inhibition
31. I (inhibitor) resembles S (substrate)
I binds at active site reversibly
E●I cannot bind to S so no reaction
Competitive inhibition: Occurs when the inhibitor binds reversibly to the
same site that the substrate would normally occupy and, therefore,
competes with the substrate for that site.
32. No I
+I
+more I
Vmax
Km
In competitive inhibition, addition of enough
substrate can overcome the inhibition.
same Vmax
33. Effect of competitive inhibitor on Vmax:
The effect of a competitive inhibitor is reversed by increasing [S]. At a
sufficient high substrate concentration, the reaction velocity reaches
the Vmax as observed in the absence of inhibitor.
Effect of competitive inhibitor on Km:
A competitive inhibitor increases the apparent Km for a given substrate
which means that, in the presence of a cmpetitive inhibitor, more
substrate is needed to achieve ½ Vmax.
Statin drugs: competitively inhibits HMG-CoA reductase (rate
limiting enzyme) and thus inhibit synthesis of cholesterol, thereby
lowering plasma cholesterol levels.
34. Noncompetitive inhibition:
Occurs when the substrate and inhibitor bind at different sites
on the enzyme, binds either free enzyme or the ES complex,
thereby preventing the reaction.
E + S E●S E + P
+ +
I I
E●I E●S●l
inhibitor
substrate
Inhibitor binds the enzyme somewhere
different from where the substrate binds.
So the inhibitor does not care whether
substrate is bound or not.
Inhibitor changes the conformation of
the enzyme at the active site so reaction
is not possible with inhibitor bound.
35. Effect on Vmax:
Noncompetitive inhibition can not be overcome by increasing the
concentration of substrate, thus decrease the apparent Vmax of the
reaction.
Effect on Km:
Noncompetitive inhibitors do not interfere with the binding of
substrate to enzyme, thus the enzyme shows the same Km in the
presence or absence of noncompetitive inhibitor.
eg:
Pb noncompetitively binds with Ferrochelatase and inhibits
insertion of iron into protoporphyrin (a precursor of heme).
36. Irreversible Inhibition
combine covalently to enzyme so as
to permanently inactivate it
(previous examples are all reversible)
almost all are very toxic
most bind to a functional group in
active site of enzyme to block that site
37. Example 1:
Diisopropyl fluorophosphate (DFP) binds covalently with
serine proteases and acetylcholinesterase – used as biological
weapon.
Sarin (DFP derivative) is a deadly nerve gas Paralysed in
certain functions because of the failure of nerve impulses to be
transmitted properly.
DFP + Acetylcholinesterase = Diisopropylphosphate ester of
cholinesterase (inactive) + HF
Once acetyl choline has been secreted it binds to the receptor sites to
the next nerve cells to propagate the nerve impulses. Before the
second impulse, acetylcholine must be hydrolysed by
acetylcholinesterase in the junction. The irreversible inhibitor DFP is
very reactive and combines with acetylcholinesterase and the
derivative has no longer functional capacity.
38. Example 2:
penicillin and related antibiotics bind covalently
to a peptidase involved in cell wall synthesis in
bacteria
Staphylococci, Streptococci sp.
39. Regulatory Enzymes
Enzymes whose activity is modulated through various types
of molecular signals, are called regulatory enzymes.
Two major classes of regulatory enzymes:
• Allosteric or noncovalently regulated enzymes
• Covalently regulated enzymes
40. Allosteric enzymes: The term allosteric derives from Greek
word which means other sites, that is allosteric enzymes are
those having other sites.
Like all enzymes, allosteric enzymes have catalytic sites, which
bind the substrate and transform it, but they also have one or
more allosteric sites for noncovalent binding of regulatory
compounds which are generally small metabolites or cofactors.
The allosteric site is specific for its modulator, allosteric enzyme
molecules are generally larger and more complex than those of
simple enzymes, most of them have two or more polypeptide
chains or subunits, allosteric enzymes usually show significant
deviations from classical Michaelis-Menten behavior.
41.
42. Kinetics of Allosteric enzymes:
Allosteric enzymes show relationships between velocity and substrate
concentrations that differ from Michaelis-Menten kinetics. Allosteric enzyme
shows sigmoidal curve rather than hyperbolic curves like all other non-
regulatory enzymes. Sigmoid kinetic behavior generally reflects cooperative
interactions between protein subunits.
Enzyme
43. Enzymes in clinical diagnosis
Plasma enzymes: There are two types of plasma enzymes
a) Relatively small group of enzymes are actively secreted into
the blood by certain cell types for specific functions.
b) A large number of enzymes are released from cells during
normal cell turnover. These enzymes normally functions
intracellularly and have no physiologic use in plasma. In
healthy individuals these enzymes are fairly constant.
Elevation of these enzymes in plasma indicates tissue
damage.
44. C. Increased levels of ALT/GPT indicates hepatic tissue damage,
Normal range : up to 40 U/L
Creatin kinase (CK): two subunit, M and B,
Three isozymes: CK1=BB, CK2=MB, CK3=MM
Myocardial muscle is the only tissue that contains CKMB, more
than 5% of total CK is CKMB,
In acute myocardial infarction, CKMB elevated in 4 to 8hrs, max
in 24 hrs, returns to normal in 48 to 72hrs,
Range: 25 U/L
Troponin I: highly specific for myocardial infarction, appears in
plasma within 4 to 6 hrs, max in 8 to 28hrs, remain elevated for 3
to 10days,
Range: normal <0.1ng/ml, 0.1-0.25 intermediate, >0.25ng/ml
moderate to severe
45. Enzymes may catalytically defective due to genetic
mutation
Disease Defective Enzyme
Albinism Tyrosine 3-monooxygenase
Alkaptonuria Homogentisate 1,2-dioxigenase
Galactosemia Galactose 1-PO4 uridylyl transferase
Phenylketonuria Phenylalanine 4-monooxigenase