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
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