The amide groups of insulin

Abstract
The positions of the amide groups of insulin were determined by estimating the relative ionophoretic mobilities and the amide contents of peptides from enzymic hydrolysates of fractions A and B of oxidized insulin. These were on the amino acid residues in positions 5, 15, (glutamic), 18 and 21 (aspartic acid) of the A type polypeptide chain and 3 and 4 (aspartic and glutamic acid) of the B type chain.