PROTEINSDescriptionNature of ProteinsTerms Dipeptide Tripeptide Proteose PeptoneClassification of Proteins Simple Conjugated DerivedCaloric Value of ProteinsCommon Protein Rich FoodsFunctions of ProteinsAmino Acids Composition Classification
PROTEINS Came from a Greek word “prota” meaning “of the first rank” or “of primary importance” the most versatile macromolecules in living systems and serve crucial functions in essentially all biological processes. An essential component of the cells and tissues used for structural purposes Broken down to AMINO ACIDS by PROTEASES An organic compound A macronutrient
NATURE OF PROTEINS Proteins are highly complex molecules Basically contain C, H, O, N arranged into amino acids Often include P, S, Fe, Cu, I, Zn, and Mn Consists of amino acids held together by peptide linkage.
NATURE OF PROTEINS Synthesized by living cells and are an essential part of the structure of the cell and its nucleus. Proteins are stored in plants in the form of aleurone grains. They are required for animals as the source of nitrogen in food. Proteins are hydrolyzed to form simpler substances and ultimately amino acids.
DIPEPTIDE Compound of 2 amino acids Produced from polypeptides by the action of the hydrolase enzyme dipeptidyl peptidase. Examples: Aspartame Carnosine Anserine
T RIPEPTIDE Compound made of 3 amino acids Examples: Glutathione Melanostatin
P ROTEOSE Compound of an intermediate substance between a protein and a peptone water-soluble compounds that are produced during digestion by the hydrolytic breakdown of proteins short of the amino acid stage Also called ALBUMOSE
P EPTONE Any of various water-soluble protein derivatives obtained by partial hydrolysis of a protein by an acid or enzyme during digestion used in nutrient media for growing bacteria and fungi derived from animal milk or meat digested by proteolytic digestion
C OMPLETE PROTEINS In food which contains all the essential amino acids in significant amounts and in proportions fairly similar to those found in the body. Can completely supply needs of the body Ex: Those derived from animal sources like meat, fish, egg, milk and cheese Only food from animal that is not complete is GELATIN
I NCOMPLETE PROTEINS Cannot be synthesized into body proteins because they are missing or deficient in one or more essential amino acids Ex: Grains, nuts, fruits, vegetables
C OMPLEMENTARY PROTEINS Supplements incomplete proteins with the amino acids that it lacks Amino acids cannot be stored in tissue until other come along later All essential amino acids need to be available in the right proportions to each other at about the same time so body can use them for tissue synthesis
L IMITING AMINO ACIDS One essential amino acid that is present in smallest amount
C LASSIFICATION OF P ROTEINS-Based on solubility, physical properties and chemicalcomposition Simple Conjugated Derived
Protein Description ExamplesSIMPLE PROTEINS •The simplest •Albumins •Made of amino acid units only, •Globulins joined by peptide bond •Glutelins •Upon hydrolysis they yield •albuminoids mixture of amino acids and nothing else.CONJUGATED •composed of simple proteins •NucleoproteinsPROTEINS combined with a non-protein •Glycoproteins substance •Phosphoproteins •The non-proteinous substance is •Hemoglobins called prosthetic group or cofactor.DERIVED PROTEINS •not naturally occurring proteins •Peptones •obtained from simple proteins by •Peptides the action of enzymes and •proteoses chemical agents. •Results from hydrolysis of proteins
CALORIC VALUE MACRONUTRIENT CALORIES PROTEINS 4 CARBOHYDRATES 4 LIPIDS/FATS 9*A gram of alcohol provides 7 calories
CALORIC VALUE imagine a food containing 10 grams of protein, 10 grams of fat, and 10 grams of carbohydrates. That would total 170 calories: (10 g protein x 4) + (10 g fat x 9) + (10 g carbs x 4) = 170 In this imaginary food 40 calories come from protein, 90 calories come from fat, and 40 calories come from carbohydrates.
C OMMON PROTEIN RICH FOODS Milk Lean Meats, Fish, and Soy Milk Poultry Eggs Beans, Tofu, Lentils, Cheese and other Legumes Yogurt Grains, including bread and pasta Peanut Butter Nuts and Seeds
F UNCTIONS OF P ROTEINS Proteins are structural materials of animal body and help in the growth of animal body. Proteins are also involved in nervous defence, metabolic regulation, biochemical catalyst and oxygen support. They build new tissues and maintain already present tissues.
ANTIBODIES Play a very important role in the immune system. Proteins with special shapes that recognize and bind to foreign substances, such as bacteria or viruses, surrounding them so that scavenger cells can destroy them and flush them out of the body. One way antibodies destroy antigens is by immobilizing them so that they can be destroyed by white blood cells.
ANTIBODIES Has 2 separable functions: recognize and attach themselves to substances that cause disease act as markers, sending signals to other parts of the immune system to attack and eliminate the disease-associated substances
C ONTRACTILE PROTEINS Proteins responsible for movement Examples are actin, myosin, troponin, and tropomyosin
E NZYMES Protein catalysts that increase the rate of reactions without themselves being changed in the overall process. often referred to as catalysts because they speed up chemical reactions. Can arrange sequence of events Able to degrade nutrients (digestion) Can transform chemical energy to another form of energy
E NZYMES PROENZYME/ZYMOGEN – inactive form of enzyme COFACTOR – non protein substance which activates enzymes APOENZYME – protein portion of enzymes Examples: LACTASE Lactose PEPSINPROTEINS MALTASE Maltose
E NZYMES : C LASSIFICATION1. Oxidoreductases2. Transferases3. Hydrolases4. Lyases5. Isomerases6. Ligases
H ORMONAL PROTEINS messenger proteins which help to coordinate certain bodily activities. Examples: insulin, oxytocin, and somatotropin. Insulin regulates glucose metabolism by controlling the blood-sugar concentration. Oxytocin stimulates contractions in females during childbirth. Somatotropin is a growth hormone that stimulates protein production in muscle cells.
S TRUCTURAL PROTEINS fibrous and stringy and provide support. maintaining structures of other biological components, like cells and tissues. Examples: keratin, collagen, and elastin Keratins strengthen protective coverings such as hair, quills, feathers, horns, and beaks. Collagens and elastin provide support for connective tissues such as tendons and ligaments.
S TORAGE P ROTEINS biological reserves of metal ions and amino acids found in plant seeds, egg whites, and milk Examples: Ovalbumin, Casein, Ferritin Ferritin stores iron. Ovalbumin is the main protein found in egg white (made up of 385 amino acids) Casein is commonly found in mammalian milk. It supplies amino acids, carbohydrates and two inorganic elements, calcium and phosphorus
T RANSPORT PROTEINS Carrier proteins which move molecules from one place to another around the body Examples: hemoglobin and cytochromes Hemoglobin transports oxygen through the blood. Cytochromes operate in the electron transport chain as electron carrier proteins. Vital to the growth and life of all living things
A MINO A CIDS Molecules containing an AMINE group, CARBOXYLIC ACID group and a SIDE CHAIN which gives it variability Its key elements are C, H, O, and N Building blocks of proteins Can be linked together in varying sequences to form a vast variety of proteins
A MINO A CIDS More than 300 Only 20 in mammalian proteins Phenylalanine,Valine, Threonine,Tryptophan, Isoleucine, Me thionine, Histidine, Arginine, Leucine, Lysine Glycine, Alanine, Serine, Tyrosine, Cysteine, Aspartic Acid, Asparagine, Glutamic Acid, Glutamate, Proline
A MINO A CIDS STANDARD AMINO ACIDS naturally incorporated into polypeptides proteinogenic or natural amino acids NON-STANDARD AMINO ACIDS non-proteinogenic not found in proteins or are not produced directly and in isolation by standard cellular machinery
A MINO A CIDS There are 22 different amino acids ordinarily required for synthesis of tissue proteins Of these, 20 are encoded by the universal genetic code Absence of any of these amino acids could prevent body protein formation ESSENTIAL amino acids NON-ESSENTIAL amino acids
N ON -E SSENTIAL A MINO A CIDS Amino acids that can be produced in the body Need not be supplied in the diet Functions in body are equally as important as those of the Essential amino acids Glycine Serine Alanine Proline Glutamate Glutamic Acid Asparagine Aspartic Acid Tyrosine Cysteine
E SSENTIAL A MINO A CIDS Indispensable amino acid Amino acids that cannot be synthesized by the body Must be supplied in the diet. Phenylalanine Methionine Valine Histidine Threonine Arginine Tryptophan Lysine Isoleucine Leucine