(a) How did Eli-Lilly company produce genetically engineered insulin? Explain.

(b) Differentiate between the insulin thus prepared and that produced naturally in the human body.

a) Human insulin also called as beta-insulin is prepared by the beta cells of cells of langerhans.

Human insulin before maturity contains a C-chain binding the A and B chain which on maturation disappears.

So the company Eli-Lilly formed the A and B chains in large quantities using plasmid of E. coli separately. Then these chains are attached to each other using a disulphide bond to form human insulin and are thus called as Humulin.

b) The only difference between the prepared insulin and natural insulin is that natural human insulin initially contains an extra stretch of chain called the C-peptide. This chain is removed during maturation and the two A and B chains are attached by disulphide bond. In prepared insulin the A and B chain are produced in plasmids separately and then joined via disulphide bond.