M. Aoyama, K. Kurihara, K. Shibata
Sep 13, 1965
Citations
0
Influential Citations
20
Citations
Journal
Biochimica et biophysica acta
Abstract
Abstract Cyanuric fluoride, which is a reagent employed to differentiate between free and bound or buried tyrosine residues in proteins, reacts with one of the two tyrosine residues in each peptide chain, A or B, of insulin. By digestion of cyanuric fluoride-treated insulin with trypsin (EC 3.4.4.4) and with chymotrypsin (EC 3.4.4.5), the two tyrosine residues not reacting with cyanuric fluoride were located in the amino acid sequence. The A14 and B26 tyrosine residues were thus found to be the non-reactive type, and the A19 and B16 residues were the reactive type. The non-reactive B26 residue was transformed into the reactive type by tryptic digestion of native insulin, while the A14 residue remained non-reactive or bound after tryptic or chymotryptic digestion. From these effects of digestion on the reactivity as well as on the rate of ionization of the tyrosine residues, the intra-chain hydrogen bonding between the side chains of the B26 tyrosine and the B22 arginine and the inter-chain hydrogen bonding between the side chains of the A14 tyrosine and the B13 glutamica cid were suggested.