The Amino Acid Sequence of the C‐Peptide of Human Proinsulin

Abstract

The determination of the amino acid sequence of the C‐peptide of human proinsulin is presented. Two constituent fragments of C‐peptide, Chy 1 + 2 and Chy 3 (residues 1–24 and 25–31, respectively) were liberated by mild chymotryptic digestion and isolated by gel filtration and ion exchange chromatography. From Chy 1 + 2 was obtained seven smaller peptides by further digestion with chymotrypsin. The sequence analysis of these fragments allowed an overall structure to be assigned. Papain digestion of the intact C‐peptide provided 12 peptides, the compositions of which provided unequivocal confirmation for the proposed sequence. Copyright © 1971, Wiley Blackwell. All rights reserved