Question

Name the source from which insulin was extracted in earlier times. Why is this insulin no more in use by the diabetic patients?

Answer 1

Insulin from an animal source, though it caused some patients to develop allergy or other types of reactions to the foreign protein. 

Insulin consists of two short polypeptide chains : 

chain a and chain b, which are linked together by disulphide bridges. In mammals, including humans, insulin is synthesized as a pro-hormone, which contains an extra stretch called the C-peptide.