Synthesis of human connecting peptide derivatives and their immunological properties

Summary Synthesis of human C-peptide (human proinsulin 33–63 ) (I), [64-formyllysine]-human proinsulin 31–65 (II) and [41-glutamic acid, 43-glutamine, 64-formyllysine]-human proinsulin 31–65 (III) are described. Immunological reactivities of these synthetic polypeptides were examined using a guinea pig antiserum to the natural human C-peptide conjugated with rabbit serum albumin. I, II and the natural human C-peptide displaced 125 I-tyrosylated natural human C-peptide from the antibody almost identically, while III failed to completely displace the labeled peptide.