First hormone prepared by genetic engineering is
Insulin was the first hormone prepared by genetic engineering with E-coli bacterium. Insulin is made of two different chains - one chain of 20 amino acid residues and another chain of 30 amino acid residues. Two different E-coli bacterial cultures were used to produce each of the insulin chain, these were then recovered from the bacteria and separated by β-galactosidase and finally chemically joined in-vitro to make commercially manifactured insulin.