Clearance of Porcine Insulin, Proinsulin, and Connecting Peptide by the Isolated Rat Liver

In the isolated rat liver perfusion system, the immunological half-life of crystalline single-component insulin was 17 min. In contrast, there was no significant clearance of either proinsulin or the connecting peptide that links the A and B chain of insulin in the proinsulin molecule. There was also no evidence of conversion of proinsulin to insulin. This may, in part, explain the prolonged in vivo half-life of proinsulin relative to insulin.