Introduction to protein and classification

1. Introduction to
protein and
classification

2. Presented by:
M.Sohail Riaz
Presented to:
Ma’am Anum

3. Table of contents
 Introduction
 Protein structure
 Classification based on shape
 Classification based on functions

4. Introduction
 Protein name is derived form a Greek word PROTOS
which means “the first or the supreme.
 Protein are extremely complicated and nitrogenous
molecule made up of variable number of amino
acid residue joined to each other by a specific
covalent bond called peptide bond.
 20 amino acid which have been found to occur in all
proteins, known as standard amino acid

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 Amino acids are the building blocks of protein
 Amino acids are linked by peptide bonds
 A polypeptide is a polymer of amino acid
 Polypeptide range in length from a few to more
than a thousand monomers

6. Protein structure
 There are 4 structure of protein:
1. Primary structure
2. Secondary structure
3. Tertiary structure
4. Quaternary structure

7. Primary structure
 The sequence of amino acids in a protein, is like the
order of letters in a long word
 Linear, ordered and 1 dimensional
 Written from amino end to carboxyl end that is N to
C

8. Secondary structure
 The folding of polypeptide chain into specific coiled
structure held together by H-bond
 Alpha-helix
 Beta-pleated sheets

9. Tertiary structure
 The tertiary structure mean the overall
conformation of a polypeptide.
 Myoglobin chain is when fully extended its length is
20 time than is width.
 X-rays diffraction show that its structure is just like a
foot ball i.e. globular.
 The globular structure is due to folding and
refolding

10. Quaternary structure
 Structure form when two or more polypeptides
chains form one macro-molecule
 For example Collagen

11. Classification based on shape
 The protein are classify into two type of protein:
1. Globular protein
2. Fibrous protein

12. Globular protein
 Spheroid or ovoid in shape.
 Enzyme are mostly globular in shape.
 Subdivided into two type of protein:
1. Albumins: Water soluble.
2. Globulin: Soluble in dilute salt solution

13. Fibrous Protein
 Long thread like molecule.
 Their helical strands mainly form fibers.
 These protein are insoluble in water.
 Form structure of the tissue
 Present where support is required.
 Example: Collagen, Elastin, Keratin

14. Classification based upon Function
 Catalytic Protein: These are enzyme which may be
simple or conjugated.
1. Alkaline phosphatase
2. Alanine transaminase
 Hormonal protein: Many protein and peptide acts as
Hormone.
1. Insulin
2. Growth Hormone

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 Structural Protein: Contribute to the structure of the
tissue.
1. Collagen
2. Elastin
 Transport Protein: Serve to carry substances.
1. Transferrin carry Iron
2. Hemoglobin carry Oxygen

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 Immune Protein: Serve in defense mechanism
1. Immunoglobulin
 Contractile Protein: Takes part in the muscle
contraction.
1. Actin
2. Myosin

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 Genetic Protein: Protein present in combination with
nucleic acid.
1. Histone Protein
 Storage Protein: To store protein for nutritional
purposes.
1. Casein in Milk
2. Gliadin in Wheat

18. Thank you