The document provides an introduction to proteins, detailing their structure, classification based on shape, and classification based on function. It outlines the four levels of protein structure: primary, secondary, tertiary, and quaternary, and explains types of proteins such as globular and fibrous, as well as their roles including catalytic, hormonal, structural, transport, immune, contractile, genetic, and storage proteins. Key examples include enzymes, hormones like insulin, and structural proteins like collagen.

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