1. PROTEINS

2. PROTEINS
Description
Nature of Proteins
Terms
Dipeptide
Tripeptide
Proteose
Peptone
Classification of Proteins
Simple
Conjugated
Derived
Caloric Value of Proteins
Common Protein Rich Foods
Functions of Proteins
Amino Acids
Composition
Classification

3. 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

4. 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.

5. 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.

6. T ERMS

7. DIPEPTIDE
 Compound of 2 amino acids
 Produced from polypeptides by the action of
the hydrolase enzyme dipeptidyl peptidase.
 Examples:
 Aspartame
 Carnosine
 Anserine

8. T RIPEPTIDE
 Compound made of 3 amino acids
 Examples:
 Glutathione
 Melanostatin

9. 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

10. 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

11. 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

12. 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

13. 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

14. L IMITING AMINO ACIDS
 One essential amino acid that is present in
smallest amount

15. C LASSIFICATION OF P ROTEINS
-Based on solubility, physical properties and chemical
composition
Simple
Conjugated
Derived

16. Protein Description Examples
SIMPLE 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 •Nucleoproteins
PROTEINS 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

17. CALORIC VALUE
MACRONUTRIENT CALORIES
PROTEINS 4
CARBOHYDRATES 4
LIPIDS/FATS 9
*A gram of alcohol provides 7 calories

18. 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.

19. 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

20. 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.

21. 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

22. 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.

23. 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

24. I NFLUENZA V IRUS & A NTIBODIES

25. C ONTRACTILE PROTEINS
 Proteins responsible for movement
 Examples are actin, myosin, troponin, and
tropomyosin

26. 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

27. E NZYMES
 PROENZYME/ZYMOGEN – inactive form of
enzyme
 COFACTOR – non protein substance which
activates enzymes
 APOENZYME – protein portion of enzymes
 Examples:
LACTASE  Lactose PEPSINPROTEINS
MALTASE  Maltose

28. E NZYMES : C LASSIFICATION
1. Oxidoreductases
2. Transferases
3. Hydrolases
4. Lyases
5. Isomerases
6. Ligases

29. 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.

30. 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.

31. 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

32. 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

33. T RANSPORT PROTEINS

34. AMINO ACIDS

35. 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

36. C OMPOSITION
 Alpha Carbon
 Hydrogen
 Carboxyl group
 Amino group
 R-group

37. 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

38. 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

39. 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

40. 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

41. 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

42. E SSENTIAL A MINO A CIDS
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

43. E SSENTIAL A MINO A CIDS
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