Question

Explain in the brief the structure of insulin.

Answer 1

Hint: Beta cells of the pancreatic islets release the peptide hormone called Insulin. It is well-thought-out to be the main anabolic hormone of the body. It performs various metabolic functions like metabolism of carbohydrates, fats, proteins and helps reduce raised blood glucose levels in the blood.

Complete answer:
The liver consists of beta cells that are very sensitive to blood sugar levels so that they release insulin into the blood in response to an elevated level of glucose levels, and inhibit the discharge of insulin when glucose levels drop. Insulin increases glucose uptake and metabolism in the cells, thereby decreasing blood sugar levels. The insulin is made up of molecular mass 580 daltons and a total of 51 amino acids. It is a heterodimer of an A-chain and a B-chain, which are joined together with the help of disulfide bonds. The molecular formula of human insulin is YA ${C_{257}}{H_{383}}{N_{65}}{O_{77}}{S_6}$. The disulfide bonds link the two polypeptide chains called A-chain and B-chain which are termed as monomers. B-chain is composed of 30 residues, whereas A-chain consists of 21 amino acids. Between the positions of A7-B7, A20-B19, and cysteine residues linking disulfide bonds are formed. The A-chain exhibits two α-helical regions at A1-A8 and A12-A19 which are antiparallel; while the B chain has a central α -helix flanked by the disulfide bond on either side and two $\beta $ -sheets.

Note: Insulin is released and stored in the body as a hexamer, while the active form is the monomer. The hexamer is about 36000 Da in size. The six molecules are linked together as three dimeric units to form a symmetrical molecule. It is therapeutically used in the treatment of Diabetes Mellitus, diabetes ketoacidosis, and Hyperglycemic coma. It is also used as an antidote for calcium channel blockers, ectodermal, and wound healing.