Investigation of collision-induced dissociation products and structures of gas-phase [ M·GlyGlyHis-H]+ ( M = Fe, Ni, Cu, and Zn) complexes.

Abstract

Collision-induced dissociation is carried out for electrosprayed [Fe·GlyGlyHis-H]+, [Ni·GlyGlyHis-H]+, [Cu·GlyGlyHis-H]+, and [Zn·GlyGlyHis-H]+ complexes. [Fe·GlyGlyHis-H]+, [Ni·GlyGlyHis-H]+, and [Zn·GlyGlyHis-H]+ yield metal-bound peptide sequence ions and dehydrated ions as primary products, whereas [Cu·GlyGlyHis-H]+ generates a more extensive series of metal-bound sequence ions and a product arising from the unusual loss of a formaldehyde moiety; dehydration is significantly suppressed for this complex. Density functional theory calculations show that the copper ion-deprotonated peptide binding energy is substantially higher than those in other complexes, suggesting that there is a correlation between ion-ligand binding energy and their fragmentation behavior.