Protein metabolism
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Protein metabolism Protein metabolism Presentation Transcript

  • Dr.Mahr-un -nisa Proteins
  • Proteins-----AA  Proteins are made from 20 different amino acids, 9 of which are essential.  Each amino acid has an amino group, an acid group, a hydrogen atom, and a side group.  It is the side group that makes each amino acid unique.  The sequence of amino acids in each protein determines its unique shape and function.
  •  Amino Acids  Have unique side groups that result in differences in the size, shape and electrical charge of an amino acid  Nonessential amino acids, also called dispensable amino acids, are ones the body can create.  Nonessential amino acids include alanine, arginine, asparagines, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.
  •  Amino Acids  Essential amino acids, also called indispensable amino acids, must be supplied by the foods people consume.  Essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenyalanine, threonine, tryptophan, and valine.  Conditionally essential amino acids refer to amino acids that are normally nonessential but essential under certain conditions.
  • Amino Acid Requirements of Humans -------------------------------------------------------------------- Nutritionally Essential Nutritionally Nonessential -------------------------------------------------------------------- Argininea Alanine Histidine Asparagine Isoleucine Aspartate Leucine Cysteine Lysine Glutamate Methionine Glutamine Phenylalanine Glycine Threonine Proline Tryptophan Serine Valine Tyrosine --------------------------------------------------------------------- a “ Nutritionally semiessential.” Synthesized at rates inadequate to support growth of children.
  • What is protein  Proteins  Amino acid chains are linked by peptide bonds in condensation reactions.  Dipeptides have two amino acids bonded together.  Tripeptides have three amino acids bonded together.  Polypeptides have more than two amino acids bonded together.  Amino acid sequences are all different, which allows for a wide variety of possible sequences.
  • M. Zaharna Clini. Chem. 2009 Peptide bond
  • The Chemist’s View of Proteins  Proteins  Protein Shapes  Hydrophilic side groups are attracted to water.  Hydrophobic side groups repel water.  Coiled and twisted chains help to provide stability.
  • M. Zaharna Clini. Chem. 2009 Classification of protein  Proteins are polymers of amino acids produced by living cells in all forms of life.  A large number of proteins exist with diverse functions, sizes, shapes and structures but each is composed of essential and non-essential amino acids in varying numbers and sequences.  The number of distinct proteins within one cell is estimated at 3,000 - 5,000  The most abundant organic molecule in cells (50-70% of cell dry weight)
  • M. Zaharna Clini. Chem. 2009 Size  A typical protein contains 200-300 amino acids, but some are much smaller and some are much larger  Proteins range in molecular weight from 6,000 Daltons (insulin) to millions of Daltons (structural proteins)
  • M. Zaharna Clini. Chem. 2009 Protein Structure  Primary structure – sequence of AA  In order to function properly, proteins must have the correct sequence of amino acids.  e.g when valine is substituted for glutamic acid in the β chain of HbA, HbS is formed, which results in sickle-cell anemia.
  • M. Zaharna Clini. Chem. 2009 Secondary structure  Initial helical folding  Beta pleated sheet  Held together by Hydrogen bonding
  • M. Zaharna Clini. Chem. 2009 Tertiary Structure  Chain folds back on itself to form 3D structure  Interaction of R groups  Responsible for biologic activity of molecule
  • M. Zaharna Clini. Chem. 2009 Quaternary structure  2 or more polypeptide chains binding together  eg. Hemoglobin  Hemoglobin has 4 subunits  Two α chains  Two β chains  Many enzymes have quaternary structures
  • M. Zaharna Clini. Chem. 2009 Classification by Protein Structure  Simple Proteins (contain only amino acids) are classified by shape as –  Globular proteins: compact, tightly folded and coiled chains  Majority of serum proteins are globular  Fibrous proteins: elongated, high viscosity (hair, collagen)
  • M. Zaharna Clini. Chem. 2009 Classification by Protein Structure  Conjugated proteins contain non-amino acid groups  Amino acid portion is called apoprotein and non-amino acid portion is called the prosthetic group  It is the prothetic groups that define the characteristics of these proteins.  Name of the conjugated protein is derived from the prosthetic group
  • M. Zaharna Clini. Chem. 2009 Conjugated Proteins Classification Prosthetic group Example Lipoprotein Lipid HDL Glycoprotein Carbohydrates Immunoglo- bulins Phosphoprotein Phosphate Casein of milk
  • M. Zaharna Clini. Chem. 2009 Functions of proteins  Generally speaking, proteins do everything in the living cells  Functional classification of plasma proteins is useful in understanding the changes that occur in disease:  Tissue nutrition  Proteins of immune defense  Antibodies  Acute phase proteins  Proteins associated with inflammation  Transport proteins( albumin, transferrin)  Proteins used to bind and transport  Hemostasis  Proteins involved in forming clots and acting very closely with complement
  • M. Zaharna Clini. Chem. 2009 Functions of proteins  Regulatory  ( receptors, hormones )  Catalysis,  enzymes  Osmotic force  Maintenance of water distribution between cells and tissue and the vascular system of the body  Acid-base balance  Participation as buffers to maintain pH  Structural, contractile, fibrous and keratinous
  • Monogastric Protein Digestion  Whole proteins are not absorbed  Too large to pass through cell membranes intact  Digestive enzymes  Hydrolyze peptide bonds  Secreted as inactive pre-enzymes  Prevents self-digestion H3N+ C H C R O N H C H C O R N H C H C R O O–
  • Monogastric Protein Digestion  Initiated in stomach  HCl from parietal cells  Stomach pH 1.6 to 3.2  Denatures 40 , 30 , and 20 structures  Pepsinogen from chief cells  Cleaves at phenylalanine, tyrosine, tryptophan  Protein leaves stomach as mix of insoluble protein, soluble protein, peptides and amino acids Aromatic amino acids Pepsinogen HCl Pepsin
  • Protein Digestion – Small Intestine  Pancreatic enzymes secreted  Trypsinogen  Chymotrypsinogen  Procarboxypeptidase  Proelastase  Collagenase Zymogens
  • Monogastric Digestion – Small Intestine  Zymogens must be converted to active form  Trypsinogen Trypsin  Endopeptidase  Cleaves on carbonyl side of Lys & Arg  Chymotrypsinogen Chymotrypsin  Endopeptidase  Cleaves carboxy terminal Phe, Tyr and Trp  Procarboxypeptidase Carboxypeptidase  Exopeptidase  Removes carboxy terminal residues Enteropeptidase/Trypsin Trypsin Trypsin
  • Protein Digestion  Small intestine (brush border)  Aminopeptidases  Cleave at N-terminal AA  Dipeptidases  Cleave dipeptides  Enterokinase (or enteropeptidase)  Trypsinogen → trypsin  Trypsin then activates all the other enzymes
  • Trypsin Inhibitors  Small proteins or peptides  Present in plants, organs, and fluids  Soybeans, peas, beans, wheat  Pancreas, colostrum  Block digestion of specific proteins  Inactivated by heat
  • Protein Digestion  Proteins are broken down to  Tripeptides  Dipeptides  Free amino acids
  • Free Amino Acid Absorption  Free amino acids  Carrier systems  Neutral AA  Basic AA  Acidic AA  Imino acids  Entrance of some AA is via active transport  Requires energy Na+ Na+
  • Peptide Absorption  Form in which the majority of protein is absorbed  More rapid than absorption of free amino acids  Active transport  Energy required  Metabolized into free amino acids in enterocyte  Only free amino acids absorbed into blood
  • Absorption of Intact Proteins  Newborns  First 24 hours after birth  Immunoglobulins  Passive immunity  Adults  Para cellular routes  Tight junctions between cells  Intracellular routes  Endocytosis  Pinocytosis  Of little nutritional significance...  Affects health (allergies and passive immunity)
  • Protein Transport in the Blood  Amino acids diffuse across the basolateral membrane  Enterocytes → portal blood → liver → tissues  Transported mostly as free amino acids  Liver  Breakdown of amino acids  Synthesis of non-essential amino acids
  • Groff & Gropper, 2000 Overview of Protein Digestion and Absorption in Monogastrics
  • OVERVIEW OF AMINO ACID METABOLISM ENVIRONMENT ORGANISM Ingested protein Bio- synthesis Protein AMINO ACIDS Nitrogen Carbon skeletons Urea Degradatio n (required) 1 2 3 a b Purines Pyrimidines Porphyrins c c Used for energy pyruvate α-ketoglutarate succinyl-CoA fumarate oxaloacetate acetoacetate acetyl CoA (glucogenic)(ketogenic)
  • Amino Acid Catabolism  Deamination of Amino Acids removal of the a-amino acids Oxidative Deamination Non-oxidative Deamination Transamination
  • TRANSAMINATION
  • The term amphibolic is used to describe a biochemical pathway that involves both catabolism and anabolism
  • Reductive amination catalyzed by glutamate dehydrogenase (this is physiological important becouse high conc. Of NH4 ion are cytotoxic)
  • Glutamine synthesis is coupled to hydrolysis of ATP
  • Pyruvate is an amphibolic intermediate in synthesis of alanine
  • Glutamte dehydrogenase, glutamine synthetase and aminotranferases play central roles in amino acid biostynthsis  The combined action of the above said enzymes converts inorganic ammonium ion in to the α-amino nitrogen of AA
  • Asparagine synthesis is energetically favorable due to coupling to ATP hydrolysis
  • Serine biosynthesis(oxidation of the α-hydroxyl group of the glycolytic intermidiate 3-phosphoglycerate by 3- phosphoglycerate dehygrogenase convert it to 3- phosphohydroxypuruvate. Transamination and subsequent dephosphorylation is strongly favored)
  • Multistep pathway for glycine biosynthesis
  • Glycine is also synthesized from serine
  • Cysteine is not nutritionally essential, however it is derived from methionine +NH3 CH C H2 C O- O H2 C S CH3
  • Tyrosine is formed from phenylalanine
  • Hydroxyproline is formed after protein synthesis
  • Selenocysteine is synthesized from serine and selenophosphate
  • Amino acids that are synthesized de novo in humans. All are related by a small number of steps to glycolysis or TCA cycle intermediates.
  • Salvage pathways for formation of certain nonessential amino acids from other amino acids Amino Acid formed Precursor Amino Acid Arginine Proline Cysteine Methionine Tyrosine Phenylalanine
  • NITROGEN BALANCE Nitrogen balance = nitrogen ingested - nitrogen excreted (primarily as protein) (primarily as urea) Nitrogen balance = 0 (nitrogen equilibrium) protein synthesis = protein degradation Positive nitrogen balance protein synthesis > protein degradation Negative nitrogen balance protein synthesis < protein degradation
  • UREA CYCLE mitochondria cytosol Function: detoxification of ammonia (prevents hyperammonemia)
  • FATE OF THE CARBON SKELETONS Carbon skeletons are used for energy. Glucogenic: TCA cycle intermediates(gluconeogensis) Ketogenic: acetyl CoA, acetoacetyl CoA, or acetoacetate
  • Protein synthesis  On-going, semicontinuous activity in all cells but rate varies greatly between tissues
  • Rate of protein synthesis Ks (%/d) Tissue Pig Steer Liver Gut Muscle 23 45 5 21 39 2 Ks = fraction of tissue protein synthesized per day
  • Protein synthesis  On-going, semicontinuous activity in all cells but rate varies greatly between tissues  Rate is regulated by hormones and supply of amino acids and energy  Energetically expensive  requires about 5 ATP per one peptide bond  Accounts for about 20% of whole-body energy expenditure
  • Protein degradation  Also controlled by hormones and energy status  Method to assist in metabolic control  turns off enzymes
  • Protein synthesis and degradation  Synthesis must exceed degradation for net protein deposition or secretion  Changes in deposition can be achieved by different combinations of changes in synthesis and degradation
  • Changes in deposition Synthesis Degradation Deposition No change No change No change
  • Protein synthesis and degradation  Synthesis must exceed degradation for net protein deposition or secretion  Changes in deposition can be achieved by different combinations of changes in synthesis and degradation  Allows for fine control of protein deposition
  • Proline biosynthesis(the initial reaction of proline biosynthsis converts the ᵞ-carboxyl group of glutamate to the mixed acid anhydride of glutamate ᵞ-phospate. Subsequent reduction form glutamate ᵞ- semialdehyde,, which following spontaneously cyclization is reduced to L-Proline )
  • Protein synthesis and degradation  Other possible reasons for evolution of protein turnover include  Allows post-translational conversion of inactive peptides to active forms (e.g., pepsinogen to pepsin)  Minimizes possible negative consequences of translation errors
  • Protein catabolism  Some net catabolism of body proteins occurs at all times  Expressed as urinary nitrogen excretion  yields urea  Minimal nitrogen excretion is termed endogenous urinary nitrogen (EUN)
  • Urinary nitrogen excretion Urine KIDNEY LIVER Urea Urea CO2 Amino acids keto acids NH3 Blood
  • Protein Synthesis
  • Protein Synthesis  Synthesis= the process of building or making  DNA= (deoxyribonucleic acid) the genetic code or instructions for the cell  RNA= ribonucleic acid  Amino Acids= building blocks of proteins
  • DNA RNA Deoxyribonucleic Acid Ribonucleic Acid Sugar=deoxyribose Sugar= ribose Contains 1 more H atom than deoxyribose Double stranded Single stranded- a single strand of nucleotides Nitrogen bases: ATCG Nitrogen bases: AUCG U=Uracil
  • http://www.princeton.ed u/ http://image s2.clinicalto ols.com/ima ges/gene/dn a_versus_rn a_reversed.j pg
  • STEP 1: TRANSCRIPTION= making RNA Location: Eukaryotes-nucleus Prokaryotes-cytoplasm  1. RNA polymerase binds to the gene’s promoter  2. The two DNA strands unwind and separate.  3. Complementary nucleotides are added using the base pairing rules EXCEPT:  A=U 
  • Try this example.  Using the following DNA sequence, what would be the complementary RNA sequence?  ATCCGTAATTATGGC  UAGGCAUUAAUACCG
  • http://www.odec.ca/projects/2004/mcgo4s0/public_html/t3/mRNA%20to%20protein.gif
  •  1. Messenger RNA= mRNA is a form of RNA that carries the instructions for making the protein from a gene and delivers it to the site of translation.  Codon= three nucleotide sequence  Transfer RNA= tRNA single strands of RNA that temporarily carry a specific amino acid on one end and has an anticodon  Anticodon-a 3 nucleotide sequence that is complementary to an mRNA codon  Ribosomal RNA= rRNA- a part of the structure of ribosomes
  • Codon and Anticodon  Codon-found on mRNA Anticodon-found on tRNA http://images.google.com/imgres? imgurl=http://www.obgynacademy.com/basicsciences/feto logy/genetics/images/codon_GCA.gif&imgrefurl=http://ww w.obgynacademy.com/basicsciences/fetology/genetics/&u sg=__4MvAO2N3sXbERXQwODVDSqtsOjM=&h=160&w= 168&sz=4&hl=en&start=5&tbnid=toyuIN8drVBr4M:&tbnh= 94&tbnw=99&prev=/images%3Fq%3Dcodon%26gbv %3D2%26hl%3Den http://www.microbelibrary.org/microbelibrary/files/ccImages/Articleim ages/kaiser/tRNA_arg.jpg
  • STEP 2-TRANSLATION- Assembling proteins- in the cytoplasm  mRNA leaves nucleus and enters cytoplasm  tRNA molecules with the complementary anticodon and a specific amino acid arrives at the ribosome where the mRNA is waiting.  Peptide bond forms between amino acids  tRNA molecule leaves and a new one comes with another amino acid.  Amino acids continue to attach together until the stop codon and a protein is formed
  • SUMMARY  Transcription= process of making RNA from DNA  Translation= RNA directions are used to make a protein from amino acids • DNA→RNA →Protein  Transcription Translation nucleus Cytoplasm on ribosome
  • DNA RNA Deoxyribonucleic Acid Ribonucleic Acid Sugar=deoxyribose Sugar= ribose Contains 1 more H atom than deoxyribose Double stranded Single stranded- a single strand of nucleotides Nitrogen bases: ATCG Nitrogen bases: AUCG U=Uracil
  • Video Clips  http://www.youtube.com/watch?v=KvYEqG  http://www.youtube.com/watch?v=B6O6uR
  • DNA Replication RNA Transcription DNA polymerase is used. RNA polymerase is used. DNA nucleotides are linked. RNA nucleotides are linked. A DNA molecule is made. An RNA molecule is made. Both DNA strands serve as templates. Only one part of one strand of DNA ( a gene) is used as a template.
  • Explain the steps in protein synthesis. http://stemcells.nih.gov /info/scireport/images/f igurea6.jpg
  • Ruminant Protein Digestion  Ruminants can exist with limited dietary protein sources due to microbial protein synthesis  Essential amino acids synthesized  Microbial protein is not sufficient during:  Rapid growth  High production
  • Protein in the Ruminant Diet  Types of protein:  Dietary protein – contains amino acids  Rumen Degradable Protein (RDP) – available for use by rumen microbes  Rumen Undegradable Protein (RUP) – escapes rumen fermentation; enters small intestine unaltered  Varies with diet, feed processing  Dietary non-protein nitrogen (NPN) – not true protein; provides a source of nitrogen for microbial protein synthesis  Relatively CHEAP - decreases cost of protein supplementation
  • Ruminant Protein Feeding  Feed the rumen microbes first (RDP)  Two counteractive processes in rumen  Degradation of (dietary) protein  Synthesis of microbial protein  Feed proteins that will escape fermentation to meet remainder of animal’s protein requirements  Escape protein, bypass protein, or rumen undegradable protein (RUP)  Aldehydes increase inter-protein cross-linking  Heat treatment  Utilization depends on  Digestibility of RUP source in the small intestine  Protein quality
  • Protein Degradation in Rumen Feedstuff % Degraded in 2 hours Urea 100 Alfalfa (fresh) 90 Wheat Grain 78 Soybean Meal 65 Corn Grain 48 Blood Meal 18
  • Rumen Protein Utilization  Factors affecting ruminal degradation  Rate of passage  Rate of passage ↑ ⇒ degradation ↓  Solubility in water  Must be solubilized prior to degradation  Heat treatment  Degradation ↓  N (and S) availability  Energy availability (carbohydrates)
  • Protein Fractions  Dietary proteins classified based on solubility in the rumen  A  NPN, instantly solubilized/degraded  B1 B2 B3  Potentially degradable  C  Insoluble, recovered in ADF, undegradable
  • Ruminant Protein Digestion  Rumen microbes use dietary protein  Creates difference between protein quality in feed and protein actually absorbed by host  Microbes break down dietary protein to  Amino acids  NH3, VFAs, and CO2  Microbes re-synthesize amino acids  Including all the essential amino acids from NH3 and carbon skeletons No absorption of protein or amino acids from rumen (or from cecum or large intestine!)
  • Protein Hydrolysis by Rumen Microbes  Process with multiple steps  Insoluble protein is solubilized when possible  Peptide bonds of solubilized protein are cleaved  Microbial endo- and exo-peptidases  Amino acids and peptides released  Peptides and amino acids absorbed rapidly by bacteria  Bacteria degrade into ammonia N (NH3)  NH3 used to produce microbial crude protein (MCP)
  • Microbial Crude Protein (MCP)  Protein produced by microbial synthesis in the rumen  Primary source of protein to the ruminant animal  Microbes combine ammonia nitrogen and carbohydrate carbon skeleton to make microbial crude protein  Diet affects the amount of nitrogen entering the small intestine as microbial crude protein
  • Factors Limiting Microbial Protein Synthesis  Amount of energy  ATP  Available nitrogen  NPN  Degraded feed intake protein nitrogen (RDP)  Available carbohydrates  Carbon residues for backbone of new amino acid Microbial crude protein synthesis relies on synchronization of carbohydrate (for carbon backbones) and nitrogen availability (for amino group)
  • Microbial Protein Synthesis  Synchronization of carbohydrate and N availability  NPN supplementation  Carbohydrates used for carbon skeleton of amino acids VFA (CHO fermentation) Rumen NH3 Blood NH3 Adapted from Van Soest, 1994 Time post-feeding Concentration Carbon backbone (from CHO fermentation)
  • Microbial Protein Formation Dietary NPN Dietary Soluble RDP Microbial Proteins Amino Acids Carbon Skeletons Sulfur Other Co-factors NH3 ATP Dietary Starch Sugar Dietary Cellulose Hemicellulose rapid slow rapid slower Dietary Insoluble RDP very slow
  • Nitrogen Recycling  Excess NH3 is absorbed through the rumen wall to the blood  Quickly converted to urea in the liver  Excess NH3 may elevate blood pH  Ammonia toxicity  Costs energy  Urea (two ammonia molecules linked together)  Relatively non-toxic  Excreted in urine  Returned to rumen via saliva (rumination important)  Efficiency of nitrogen recycling decreases with increasing nitrogen intake
  • Nitrogen Recycling  Nitrogen is continually recycled to rumen for reutilization  Ability to survive on low nitrogen diets  Up to 90% of plasma urea CAN be recycled to rumen on low protein diet  Over 75% of plasma urea will be excreted on high protein diet  Plasma urea enters rumen  Saliva  Diffuses through rumen wall from blood Urea Ammonia + CO2 Urease
  • Feed Protein, NPN and CHO Feed Protein Feed NPN NH3/NH4 Bacterial N NH4 + loss MCP RDP RUP Feed Protein AA MCP AA NH3 Liver Blood Urea Salivary N ATP RUMEN SMALL INTESTINE
  • Ruminant Digestion and Absorption  Post-ruminal digestion and absorption closely resembles the processes of monogastric animals  However, amino acid profile entering small intestine different from dietary profile
  • Overview of Protein Feeding Issues in Ruminants  Rumen degradable protein (RDP)  Low protein quality in feed ⇒ very good quality microbial proteins  Great protein quality in feed ⇒ very good quality microbial proteins  Feed the cheapest RDP source that is practical regardless of quality  Rumen undegradable protein (RUP)  Not modified in rumen, so should be higher quality protein as fed to animal  May cost more initially, but may be worth cost if performance boosted enough
  • Salivary Urea NPN NH3 POOL Dietary Nitrogen Non-utilized Ammonia NH3 UREA LIVER LEVEL TO PROVIDE FOR MAXIMUM MICROBIAL GROWTH MICROBIAL PROTEIN 65% OF PROTEIN 35% OF PROTEIN SMALL INTESTINE AMINO ACIDS AMINO ACIDSPROTEIN AMINO ACIDS PEPTIDES Reticulo-rumen RUP RDP Recycled urea
  • Functional Feeds  Functional feeds may be defined as any feed or feed ingredient that produces a biological effect or health benefit that is above and beyond the nutritive value of that feedstuff  Many feeds and their components fit this definition
  • Functional Proteins  Functional proteins are feed-derived proteins that, in addition to their nutritional value, produce a biological effect in the body
  • Feedstuffs with Biologically Active Proteins  Milk  Colostrum  Whey Protein Concentrates/Isolates  Plasma or serum  Other animal-derived feedstuffs  Fish meal  Meat and bone meal  Fermented animal-based products  Yeast  Lactobacillus organisms  Soy products
  • Protein Size Affects Function  Many protein hormones are functional even when fed to animals  thyrotropin-releasing hormone (TRH, a 3-amino acid peptide)  luteinizing hormone-releasing hormone (LHRH, a 10-amino acid peptide)  insulin (a 51-amino acid polypeptide)  The smaller the peptide, the more “functional” it is when fed  100% activity for TRH, 50% for LHRH, and 30% for insulin  Feedstuffs containing protein hormones (colostrum) have biological activity when fed to animals
  • Production of Bioactive Peptides From Biologically-Inactive Proteins  Peptides produced from intact inactive proteins by incomplete digestion via proteases in stomach and duodenum or via microbial proteases in rumen  Many of these biologically active peptides (typically 2-4 amino acid residues) are stable from further digestion  Some peptides bind to specific epithelial receptors in intestinal lumen and induce physiological reactions  Some peptides are absorbed intact by a specific peptide transporter system into the circulatory system and transported to target organs
  • Responses to Feeding Functional Proteins or Peptides  Antimicrobial – including control of gut microflora  Antiviral  Binding of enterotoxins  Anti-carcinogenic  Immunomodulation  Anti-oxidant effects  Opioid effects  Enhance tissue development or function  Anti-inflammatory  Appetite regulation  Anti-hypertensive  Anti-thrombic
  • Functional Activity of Major Milk Proteins  Caseins (α, β and κ)  Transport of minerals and trace elements (Ca, PO4, Fe, Zn, Cu), precursor of bioactive peptides, immunomodulation (hydrolysates/peptides)  β-Lactoglobulin  Retinol carrier, binding fatty acids, potential antioxidant, precursor for bioactive peptides  α-Lactalbumin  Lactose synthesis in mammary gland, Ca carrier, immunomodulation, anticarcinogenic, precursor for bioactive peptides  Immunoglobulins  Specific immune protection (antibodies and complement system), G, M, A potential precursor for bioactive peptides  Glycomacropeptide  Antiviral, antithrombotic, bifidogenic, gastric regulation  Lactoferrin  Antimicrobial, antioxidative, anticarcinogenic, anti-inflammatory, immunomodulation, iron transport, cell growth regulation, precursor for bioactive peptides  Lactoperoxidase  Antimicrobial, synergistic effect with Igs and LF  Lysozyme  Antimicrobial, synergistic effect with Igs and LF  Serum albumin  Precursor for bioactive peptides  Proteose peptones  Potential mineral carrier
  • Functional Activity of Minor Milk Proteins  Growth factors (IgF, TGF, EGF)  stimulation of cell proliferation and differentation  Cytokines  regulation of immune system (interferons, interleukins, TGFβ, TNFα)  Inflammation  Increases immune response  Milk basic protein (MBP)  Promotion of bone formation and suppression of bone resorption  Osteopontin  Modulation of trophoblastic cell migration
  • Protein Fragments That Have Biological Activity
  • Functional Protein Effects During Toxin or Disease Challenge  During intestinal inflammation, some functional proteins:  Reduce  local inflammatory response  excessive activation of inflammatory cells  permeability  Increase  Nutrient absorption  Barrier function  Intestinal health  During intestinal inflammation, some functional proteins:  Are absorbed and create adverse allergenic and immune responses in the body Modified from Campbell, 2007