Combined Experimental and Theoretical Study on the Nature and the Metastable Decay Pathways of the Amino Acid Ion Fragment [<i>M</i>−H]⁻

Abstract

Breaking up is hard to do: The dominating negative-ion fragment formed by dissociative electron attachment (DEA) to amino acids or by their ionization through MALDI is [M−H]−. Three different experimental techniques and molecular dynamics calculations are used to determine the site of hydrogen loss and which metastable decay pathways (for valine, see picture; blue nitrogen, red oxygen) dominate further decay.