a. Earlier, insulin was extracted from pancreas of slaughtered cattle and pig. This insulin is not in use as some patients developed allergic reaction to this foreign protein.
b. Eli Lilly used the following procedure for insulin synthesis:
i. Two DNA sequences corresponding to A and B chains of insulin were prepared.
ii. These sequences were then introduced in plasmids of E. coli.
iii. The two insulin chains are produced separately.
iv. The two chains are extracted and combined by creating disulphide bonds to form the assembled mature molecule of insulin.
c. The pro-hormone produced in the human body has an extra stretch of C-peptide.
