Ion‐Induced Fragmentation of Amino Acids: Effect of the Environment

Abstract

In general, radiation-induced fragmentation of small amino acids is governed by the cleavage of the C-C(α) bond. We present results obtained with 300 keV Xe(20+) ions that allow molecules (glycine and valine) to be ionised at large distances without appreciable energy transfer. Also in the present case, the C-C(α) bond turns out to be the weakest link and hence its scission is the dominant fragmentation channel. Intact ionised molecules are observed with very low intensities. When the molecules are embedded in a cluster of amino acids, a protective effect of the environment is observed. The fragmentation pattern changes: the C-C(α) bond becomes more protected and stable amino acid cations are observed as fragments of the molecular clusters. Evidently, the molecular cluster acts as a "buffer" for the excess energy, capable of rapidly redistributing excess energy and charge.

Formation and Fragmentation of Protonated Molecules after Ionization of Amino Acid and Lactic Acid Clusters by Collision with Ions in the Gas Phase

“…Upon comparison of these spectra with spectra from isolated molecules, new peaks are evident. Mass spectra of isolated molecules in the gas phase ionized by highly charged ions can be found in the literature for glycine, [36,37] alanine, [22] and valine. [36] To the best of our knowledge,n oe xperimental data for isolatedl actic acid are availablef or multiply charged ion collisions.…”

“…Mass spectra of isolated molecules in the gas phase ionized by highly charged ions can be found in the literature for glycine, [36,37] alanine, [22] and valine. [36] To the best of our knowledge,n oe xperimental data for isolatedl actic acid are availablef or multiply charged ion collisions. Therefore, the presentl actic acid data were compared to spectra from electron impact ionization (NIST database [31] )a nd VUV ionization at 118nm.…”

Ion formation upon electron collisions with valine embedded in helium nanodroplets

“…Valine is important in the biosynthesis of proteins in humans who acquire valine through their diet. Previous gas-phase studies with isolated valine have provided valuable insight into the stability of this molecule against dissociation by particle collisions [7][8][9][10][11][12][13][14][15]. Low-energy electron interactions with Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.…”

A Multicoincidence Study of Fragmentation Dynamics in Collision of γ‐Aminobutyric Acid with Low‐Energy Ions

“…Considering the importance of nucleic acids as genetic information carriers, ion‐induced ionization and fragmentation of their building blocks (nucleobases and sugars) have been widely studied, both experimentally and theoretically 4. 6–13 More recently, these studies have been extended to the protein building blocks: amino acids 14–16. In α‐amino acids, the C atom closest to the acid group, C α , holds both the amino group and the side chain.…”

“…Mass spectrum of γ‐aminobutyric acid : Figure 1 a shows a mass spectrum of positive ions produced in collisions of 48 keV O 6+ with γ‐aminobutyric acid (NH 2 (CH 2 ) 3 COOH, see inset). The interaction with low‐energy multiply charged ions is dominated by electron capture, in which one or more electrons are removed from the target by charge transfer to the incoming projectile 16. 23, 24 The resulting multiply charged species are often produced in (highly) excited states, which can subsequently undergo fragmentation into several charged fragments.…”