Genetic engineering process insulin was prepared from slaughter cattle and pig it cause allergy due to some people
Insulin contain two chain A and B chain linked by disulphide bond. Human insulin is synthesised as a prohormone some process happened before it become a fully mature human insulin.
In immature insulin contain A chain, B chain and also contain extra C chain structure, after processed in mature insulin it contain only A and B chain linked together by disulphide bond.
Eli Lily an American company prepared human insulin follow biotechnology method. Extract A and B chain of DNA sequence and introduced them in plasmids of E. Coli to produce insulin chains. Creating disulphide bond in laboratory to form Human Insulin.
MBH/AB