A H-1-NMR DETERMINATION OF THE SOLUTION STRUCTURE OF THE A-CHAIN OF INSULIN - COMPARISON WITH THE CRYSTAL-STRUCTURE AND AN EXAMINATION OF THE ROLE OF SOLVENT

Abstract

The 1H-NMR chemical shift assignments for the oxidized A-chain of bovine insulin have been determined in aqueous and 30% trifluoroethanol/water solutions. Analysis of the observed medium-range nuclear Overhauser effects indicates that in aqueous solution significant populations of the peptide exist, with a 3(10)-helical conformation over residues 12-17. This region corresponds to helix A (13-20) in the crystal structure of the 2 Zn insulin hexamer. In 30% TFE solution, the NOE data are supportive of a random coil conformation throughout the peptide.