PROTEINS

PROTEINS DescriptionNature of ProteinsTerms

DipeptideTripeptideProteosePeptone

Classification of ProteinsSimpleConjugatedDerived

Caloric Value of ProteinsCommon Protein Rich FoodsFunctions of ProteinsAmino Acids

CompositionClassification

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.

TERMS

DIPEPTIDE

Compound of 2 amino acids

Produced from polypeptides by the action of the hydrolase enzyme dipeptidyl peptidase.

Examples:

Aspartame

Carnosine

Anserine

TRIPEPTIDE

Compound made of 3 amino acids

Examples:

Glutathione

Melanostatin

PROTEOSE

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

PEPTONE

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

COMPLETE 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

INCOMPLETE 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

COMPLEMENTARY 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

LIMITING AMINO ACIDS

One essential amino acid that is present in smallest amount

CLASSIFICATION OF PROTEINS

-Based on solubility, physical properties and chemical composition

SimpleConjugatedDerived

Protein Description Examples

SIMPLE PROTEINS •The simplest•Made of amino acid units only, joined by peptide bond•Upon hydrolysis they yield mixture of amino acids and nothing else.

•Albumins•Globulins•Glutelins•albuminoids

CONJUGATED PROTEINS

•composed of simple proteins combined with a non-protein substance•The non-proteinous substance is called prosthetic group or cofactor.

•Nucleoproteins•Glycoproteins•Phosphoproteins•Hemoglobins

DERIVED PROTEINS •not naturally occurring proteins•obtained from simple proteins by the action of enzymes and chemical agents. •Results from hydrolysis of proteins

•Peptones•Peptides•proteoses

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.

COMMON PROTEIN RICH FOODS

Milk

Soy Milk

Eggs

Cheese

Yogurt

Peanut Butter

Lean Meats, Fish, and Poultry

Beans, Tofu, Lentils, and other Legumes

Grains, including bread and pasta

Nuts and Seeds

FUNCTIONS OF PROTEINS

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.

PROTEIN FUNCTIONS

1. PROTECTION : Immunoglobulins

2. CONTRACTILE: Actin, Myosin

3. CATALYTIC: ENZYMES

4. HORMONAL PROTEINS: Oxytocin, insulin

5. STRUCTURAL : Collagen, Elastin, Keratin

6. STORAGE: Ferritin, Myoglobin

7. TRANSPORT: Hemoglobin, Lipoproteins

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

INFLUENZA VIRUS & ANTIBODIES

CONTRACTILE PROTEINS

Proteins responsible for movement

Examples are actin, myosin, troponin, and tropomyosin

ENZYMES

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

ENZYMES

PROENZYME/ZYMOGEN – inactive form of enzyme

COFACTOR – non protein substance which activates enzymes

APOENZYME – protein portion of enzymes

Examples:

LACTASE Lactose PEPSINPROTEINS

MALTASE Maltose

ENZYMES: CLASSIFICATION

1. Oxidoreductases

2. Transferases

3. Hydrolases

4. Lyases

5. Isomerases

6. Ligases

HORMONAL 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.

STRUCTURAL 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.

STORAGE PROTEINS

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

TRANSPORT 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

TRANSPORT PROTEINS

The building blocks of proteins

AMINO ACIDS

AMINO ACIDS

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

COMPOSITION

Alpha CarbonHydrogenCarboxyl group Amino group R-group

AMINO ACIDS

More than 300

Only 20 in mammalian proteins

Phenylalanine,Valine, Threonine,Tryptophan, Isoleucine, Methionine, Histidine, Arginine, Leucine, Lysine

Glycine, Alanine, Serine, Tyrosine, Cysteine, Aspartic Acid, Asparagine, Glutamic Acid, Glutamate, Proline

AMINO ACIDS

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

AMINO ACIDS

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

NON-ESSENTIAL AMINO ACIDS

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

ESSENTIAL AMINO ACIDS

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

ESSENTIAL AMINO ACIDS

Essential Amino Acid: Sources:

Phenylalanine Fish, beef, chicken, pork, turkey, lamb, milk, eggs, cheese, sour cream, yogurt, soy

Valine Soy, beans, peanuts, milk, egg, cheese, poultry, beef

Threonine Beans, lentils, nuts, seeds, poultry, fish, shrimp, milk

Tryptophan Milk, nuts, beans, fish, eggs, yogurt, turkey, cheese

Isoleucine Nuts, seeds, meat, fish, eggs, peas, soy

ESSENTIAL AMINO ACIDS

Essential Amino Acid: Sources:

Methionine Eggs, fish, nuts, sesame seeds, spinach, broccoli, squash

Histidine Meat, dairy products, rice, wheat, rye

Arginine Walnuts, pumpkin seeds, shrimp, crab, scallops, pork, beef

Lysine Egg, cheese, fish, milk, potatoes, red meat, soy, yeast

Leucine Cottage cheese, meat, egg, soy, sesame seeds