Protein ( introduction, classification, properties, structure, importance and disease

Proteins are macromolecules formed by amino acids. Proteins are large size molecules (macromolecules), polymers of structural units called amino acids. A total of 20 different amino acids exist in proteins and hundreds to thousands of these amino acids are attached to each other in long chains to form a protein

1. PROTEINS 11 / 2 / 202 1 Mohd Asad Farooqi (Lecturer) Mahrishi college of pharmacy

2. PROTEINS • The Molecules which yields amino acids upon hydrolysis are called proteins. • Proteins are natural polymer of amino acids. • The number of amino acids in a protein molecule may range from two to several thousands. • Protein molecules contain Nitrogen, Carbon, Hydrogen and Oxygen. 11 / 2 / 202 2

3. PROTEINS • Proteins are the basis for the major structural components of animal and human tissue. • They act as biological catalysts (Enzymes), form structural parts of organisms, participate in different cell reactions, act as molecules of immunity and also provide fuel. 11 / 2 / 202 3

4. SOLUBILIY 11 / 2 / 202 4 Soluble in water, eg., Albumin,histones etc Soluble in 70-80 % alcohol, eg.,Gliadin Soluble in dilute salt solution, eg., Globulins,( serum,milk etc) Insoluble protein, eg., Scleroprotein ( collagen,keratin etc)

5. CLASSIFICATION OF PROTEINS (a) Simple Proteins 11 / 2 / 202 5 Those which give one amino acid only upon hydrolysis. (b) Conjugated Proteins Those which give an amino acid and a non-protein group upon hydrolysis . . (c) Derived Proteins Those which are derived from simple and conjugated proteins.

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7. STRUCTURE OF PROTEINS 11 / 2 / 202 7 Depends upon the spatial arrangement of polypeptide chains. Three arrangements are possible. Four structures: Primary structure Secondary structure Tertiary Structure Quaternary Structure

8. The Primary Structure Of Proteins 11 / 2 / 202 8 The sequence of amino acids in a polypeptide chain is called a primary structure. Amino Acids are linked with one another through peptide bonds.

9. The Primary Structure Of Proteins 11 / 2 / 202 9

10. The Secondary Structure Of Proteins 11 / 2 / 202 10 Peptide chains may acquire spiral shape or may be present in a zig zig manner. This coiling of peptide chains is called the secondary structure of proteins. It is due to Hydrogen bonding.

11. The Secondary Structure Of Proteins 11 / 2 / 202 11

12. The Tertiary Structure Of Proteins Twisting or folding of polypeptide chains represents tertiary structure of proteins. 11 / 2 / 202 12

13. The Quaternary Structure Of Proteins 11 / 2 / 202 13 Quaternary means four. It is the arrangement of multiple folded protein or coiling protein molecules in a multi-subunit complex. A variety of bonding interactions including Hydrogen bonding, salt bridges and disulfide bonds holds the various chains into a particular geometry.

14. The Quaternary Structure Of Proteins 11 / 2 / 202 14

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16. Denaturation 11 / 2 / 202 16 The process that changes the shape of a protein molecule without breaking its peptide bonds. Denaturation breaks the hydrogen bonds that create the twists and turns of a protein molecule

17. Properties Of Proteins 11 / 2 / 202 17 Found in all living organisms. Involved in processes such as digestion of food, cell structure, catalysis, movement, energy manipulation etc. Complex molecules. Polymers of amino acids. Long chains of amino acids are called Polypeptides.

18. Importance of Proteins Proteins play an important role in formation of protoplasm. 11 / 2 / 202 18

19. Importance of Proteins Nucleoproteins are complex proteins and act as the carrier of heredity materials from one generation to another. 11 / 2 / 202 19

20. Importance of Proteins Enzymes are the biological catalyst and they are also proteins 11 / 2 / 202 20

21. Importance of Proteins Hemoglobin is a protein. It act as oxygen carrier. 11 / 2 / 202 21

22. Importance of Proteins Gelatin is obtained by heating bones, skins and tendons in water. It is used in bakery goods. 11 / 2 / 202 22

23. QUALITATIVE CHEMICAL TESTS 11 / 2 / 202 23

24. Biuret test – general test for detecting the presence of peptide bond. Named after the compound, biuret reagents: cuso4 solution and dilute naoh Positive result: formation of pink to violet to blue color principle: complexation of cu+2 with amide N atoms . 11 / 2 / 202 24

25. Ninhydrin test – general test for detect ammonia or primary and secondry amines. One of the most sensitive color reactions known Reagent/s: ninhydrin (1,2,3 - indanetrione monohydrate) in ethanol positive result: blue to blue violet color Principle: oxidative deamination and decarboxylation; reduction of ninhydrin Proline, hydroxyproline, and 2-, 3-, and 4-aminobenzoic acids fail to give a blue color but produce a yellow color instead 11 / 2 / 202 25

26. Xanthoproteic test – general test for aromatic amino acids such as tryptophan, phenylalanine, histidine an d tyrosine . Presence of electron donating substituents enhances reaction rate. Reagents: conc. HNO3 and conc. Naoh (neutralize excess acid). Positive results: formation of yellow precipitate and after addition of excess naoh (alkaline), an orange precipitate forms. Principle involved: nitration of aromatic rings (i.E. Indole in tryptophan!) Via electrophilic aromatic substitution. 11 / 2 / 202 26

27. Sakaguchi test – specific for arginine (guanido group) Reagents:-napthol, naoh and naobr (and urea to stabilize color and destroy excess obr- anions). Positive result: red to red-orange color. Principle: base-catalyzed condensation of napthol with the guanido group of arginine. 11 / 2 / 202 27

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29. PROTEIN DEFICIENCY DISEASE 11 / 2 / 202 29

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