Determination of the amino acid sequence of the monkey, sheep, and dog proinsulin C-peptides by a semi-micro Edman degradation procedure.

Proinsulin C-peptides were isolated from the pancreas of the green monkey, sheep, and dog by established procedures. The amino acid sequences of these peptides have been determined using a semi-micro adaptation of the Edman degradation procedure. These sequences are compared with those of the human, bovine, porcine, and rat C-peptides. The bovine and ovine C-peptide sequences are identical, whereas the dog sequence appears to contain an 8 residue deletion near the NH2 terminus. Although the C-peptide sequences vary much more than the insulin A and B chain sequences among these species, several prominent features of the C-peptide structure have been conserved.