Proteins

PROTEINS

Proteins are polypeptides. i.e., linear chains of amino acids linked past times peptide bonds.

A Peptide bond is formed when –COOH grouping of 1 amino acid reacts alongside –NH2 grouping of side past times side amino acid past times releasing a molecule of H2O (dehydration).

Proteins are Heteropolymer of amino acids. i.e, unlike types of amino acids are linked through peptide bonds to shape protein.

There are xx types of amino acids involved inward protein synthesis. They are

1. Alanine (Ala)  
2. Arginine (Arg)  
3. Asparagine (Asn)  
4. Aspartic acid (Asp) ) 
5. Cystein (Cys)  
6. Glutamine (Gln)  
7. Glutamic acid (Glu)  
8. Glycine (Gly)  
9. Histidine (His)  
10. Isoleucine (Ile) 
11. Leucine (Leu)
12. Lysine (Lys)
13. Methionine (Met)
14. Phenyl alanine (Phe
15. Proline (Pro)
16. Serine (Ser)
17. Threonine (Thr)
18. Tryptophan (Trp)
19. Tyrosine (Tyr)
20. Valine (Val)

Amino acids are two types:

• Essential amino acids: They cannot hold upward synthesized past times the trunk as well as should hold upward supplied through diet. E.g. Lysine, leucine, isoleucine, tryptophan etc.
• Non-essential amino acids: They tin hold upward synthesized past times the body. E.g. Glycine, alanine, serine, arginine etc.

Functions of protein:

• For increase as well as tissue repair.
• Many proteins carry nutrients across prison theater cellphone membranes. E.g. GLUT-4 enables glucose carry into cell.
• Many proteins deed every bit intercellular terra firma substance. E.g. collagen.
• Some proteins component every bit antibodies to cause out infectious organisms (pathogens) such every bit bacteria.
• Some proteins deed every bit receptors. E.g. receptors of smell, taste, hormones etc.
• Many proteins are hormones. E.g. Insulin, glucagon etc. 
• Many proteins deed every bit enzymes. E.g. trypsin, pepsin, lactase, sucrase etc. 
• Some proteins deed every bit pigments. E.g. hemoglobin, myoglobin, chlorophyll etc.

Most abundant poly peptide inward fauna world: Collagen 

Most abundant poly peptide inward the biosphere: Ribulose biphosphate carboxylase - oxygenase (RuBisCO)

Structural Levels of protein

Proteins convey iv structural levels. They are

1. Primary structure
2. Secondary structure
3. Tertiary structure
4. Quaternary structure

• Primary structure: It describes the sequence of amino acids, i.e. the positional data inward a protein. Left terminate of the chain has outset amino acid (N-terminal amino acid). Right terminate has final amino acid (C-terminal amino acid).
• Secondary structure: Influenza A virus subtype H5N1 poly peptide thread is folded inward the shape of a helix. It has exclusively correct handed helices.
• Tertiary structure: Long poly peptide chain is folded upon itself similar a hollow woolen ball. It gives 3-D persuasion of protein. Tertiary construction is necessary for many biological activities of proteins.
• Quaternary structure: Some proteins are an assembly of to a greater extent than than 1 polypeptide or subunits. E.g. Hb has iv subunits (2 α subunits as well as two β subunits).