Formation of native insulin from the scrambled molecule by protein disulphide-isomerase.

The formation of native insulin either from scrambled insulin or from the separated A chain and B chain S-sulphonates by protein disulphide-isomerase was demonstrated with yields of 20-30% as measured by h.p.l.c. analysis, receptor binding and stimulation of lipogenesis. The h.p.l.c. profile of the reaction products shows that, among all the possible isomers containing both chains, the native hormone is by far the predominating product and consequently the most stable under certain conditions.