NEET · BiologyHard

In the production of recombinant human insulin, the A and B polypeptide chains are produced separately in E. coli. What is the final step required to form the functional hormone?

  1. A.Proteolytic cleavage of the C-peptide from the proinsulin molecule
  2. B.Formation of disulfide bonds between the A and B chains in vitro
  3. C.Glycosylation of the polypeptide chains in the bacterial cytoplasm
  4. D.Removal of the signal peptide sequence by bacterial signal peptidases
Show correct answer & step-by-step solution

Correct answer: BFormation of disulfide bonds between the A and B chains in vitro

Solution

  1. Human insulin is synthesized as a precursor called proinsulin containing A, B, and C chains.
  2. Bacteria lack the machinery to excise the C-peptide from proinsulin.
  3. Therefore, the A and B chains are expressed as separate fusion proteins in E. coli.
  4. These chains are purified and linked together by creating disulfide bonds in a controlled chemical environment.
  5. Hence the answer is (B).

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