Which of the following statements regarding the structure of proinsulin and mature insulin are not correct ?
(i) Proinsulin is made up of three polypeptide chains -A,B and C
(ii) c- polypeptide chain with 33 amino acids is removed prior to insulin formation
(iii) Mature insulin is made up of 51 amino acids arranged in two polypeptide chain -A and B
(iv) Polypeptide chain A has 30 amino acids and polypeptide chain B has 21 amino acids
(v) Polypeptide chains A and B are interconnected by only one S-S linkage.