Monomeric destetrapeptide human insulin from a precursor expressed in Saccharomyces cerevisiae

Destetrapeptide insulin (DTI, human insulin with B27-30 removed) was obtain ed from a monomeric precursor (MIP) expressed in Saccharomyces cerevisiae t hrough tryptic transpeptidation in the presence of synthetic tetrapeptide G ly-Phe-Phe-Tyr. The in vivo biological activity of DTI, determined by mouse convulsion assay, is 22 IU/mg, Its binding activity with insulin receptor on human placental membrane is 80% and its in vitro biological activity, de termined by free fat cell assay, is 77%. Compared with native insulin, DTI molecules do not associate in solution but exist in the monomeric form, thu s leading to its rapid utilization in vivo.