Peptide bond tautomerization induced by divalent metal ions: Characterization of the iminol configuration

Abstract

Rearranged: The attachment of gas-phase divalent metal ions that bind as strongly as Mg 2+ and transition-metal ions to the dipeptide PhePhe results in displacement of the amide proton by the newly characterized iminol tautomerization rearrangment. More weakly coordinating ions bind in the known charge-solvation mode. Infrared multiple-photon dissociation spectroscopy using the free-electron laser clearly shows the tautomeric transition. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.