Explain the various steps involved in the production of artificial insulin.

* Insulin contains two short polypeptide chains: chain A and chain B linked together by disulphide bridges.
* In mammals insulin is synthesised as a pro-hormone. It contains an extra stretch called C-peptide.
* C-peptide is absent in the mature insulin and is removed during maturation into insulin.
* Production of insulin by rDNA techniques was achieved by an American company, Eli Lilly in 1983. It prepared two DNA sequences corresponding to A and B, chains of human insulin and introduced them in plasmids of E. coli for production. The A and B chains produced were separated, extracted and combined, by creating disulfide bonds to form human insulin.