Download - PROTEINS. proteins Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

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Page 1: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

PROTEINS

Page 2: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

proteins

Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

Page 3: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

Amino acid

amino acid are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids.

Page 4: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

Amino acid

general formula for α-amino acid is

where R is an organic substituent. The amino group is attached to the carbon atom immediately adjacent to the carboxylate group (the α–carbon ).

Page 5: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.
Page 6: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

Amino acid:

There are two types of amino acids: non-essential amino acids can be

made by the body. essential amino acids cannot be made

by the body and must be taken from food. There are 8 essential amino acids.

Page 7: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

Amino acid

essential amino acid isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

histidine is considered semi-essential because the body does not always require dietary sources of it.

Page 8: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

Importance of proteins:

Structural Proteins (Membranes, cartilages, Connective tissues).

Transport Proteins Direct biochemical reactions (enzymes) Defend the body against infection

(antibodies) Control metabolic process (hormones) Contractile Proteins - are responsible for

movement

Page 9: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

albumin

Albumin is the main protein of blood plasma; it binds to water, cations (such as Ca2+, Na+ and K+), fatty acids, hormones, bilirubin and drugs

Page 10: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

gelatin

Gelatin is a translucent, colorless, brittle (when dry), tasteless solid substance

derived from the collagen inside animals' skin and bones.

It is commonly used as a gelling agent in food, pharmaceuticals, and cosmetic manufacturing.

Page 11: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

Physical properties

Page 12: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

a. Protein solubility

All proteins dissolve in dilute acid ,base and water

Page 13: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

b. Coagulation and precipitation test

1.precipitation by heat:White turbidity will appear

Page 14: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

b. Coagulation and precipitation test

2.precipitation by conc. Acid: Add 2ml of conc. Nitric acid in a test

tube then in the wall of the tube add 2ml of protein solution

ResultWhite ppt will appear

Page 15: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

b .Coagulation and precipitation test

3.Precipitation by minerals Result:Ppt will appear

Page 16: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

b. Coagulation and precipitation test

4.precipitation by alkaloids Result:Ppt will appear

Page 17: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

b. Coagulation and precipitation test

5.preciptation by alcohol :Add to 3ml protein solution 6ml of(70-90%) of ethyl alcohol Result:Ppt will appear

Page 18: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

c. Gel formation test:

Dissolve 0.5 g of gelatin in 10ml hot H2O in test tube then cool the test tube in ice bath

Result: Gel will formed

Page 19: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

Chemical tests

Page 20: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

Chemical tests:

General test for all protein Biuret test:Add 3ml of protein solution , 3ml of 10% NaOH with shake, then add 2 drops of 1% CuSO4 after shake violet color will appear

Page 21: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

Chemical tests

Differentiation (specific) test: Millon test:Add 2ml of protein solution, 5drops of millon’s reagent.Result:+ve albumin (white ppt)-ve gelatin (no white ppt)Then heat the test tube . red ppt will appear with (albumin and gelatin)

Page 22: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

Chemical tests:

Differentiation (specific) test: Lead acetate test :Add to 0.5 ml of protein solution 0.5ml of 20% NaOH heat the test tube in water bath for 1 min. then add 2 drops of conc.lead acetate Result:Brown color(+ve) with albumin-ve with gelatin

Page 23: PROTEINS. proteins  Proteins are polymers composed of sub-units called amino acids that are linked by peptide (amide) bond.

Thank youand good luck in

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