In:
ChemPhysChem, Wiley, Vol. 10, No. 9-10 ( 2009-07-13), p. 1619-1623
Abstract:
The branching ratio between ammonia loss and NC α bond cleavage of singly charged microsolvated peptides after electron capture from cesium depends on the solvent molecule attached. Density functional calculations reveal that for [GA+H] + (CE) (G=glycine, A=alanine, CE=crown ether), the singly occupied molecular orbital of the neutral radical is located mainly on the amide group (see picture). magnified image The results from an experimental study of bare and microsolvated peptide monocations in high‐energy collisions with cesium vapor are reported. Neutral radicals form after electron capture from cesium, which decay by H loss, NH 3 loss, or NC α bond cleavage into characteristic z . and c fragments. The neutral fragments are converted into negatively charged species in a second collision with cesium and are identified by means of mass spectrometry. For protonated GA (G=glycine, A=alanine), the branching ratio between NH 3 loss and NC α bond cleavage is found to strongly depend on the molecule attached (H 2 O, CH 3 CN, CH 3 OH, and 18‐crown‐6 ether (CE)). Addition of H 2 O and CH 3 OH increases this ratio whereas CH 3 CN and CE decrease it. For protonated AAA ([AAA+H] + ), a similar effect is observed with methanol, while the ratio between the z 1 and z 2 fragment peaks remains unchanged for the bare and microsolvated species. Density functional theory calculations reveal that in the case of [GA+H] + (CE), the singly occupied molecular orbital is located mainly on the amide group in accordance with the experimental results.
Type of Medium:
Online Resource
ISSN:
1439-4235
,
1439-7641
DOI:
10.1002/cphc.v10:9/10
DOI:
10.1002/cphc.200800782
Language:
English
Publisher:
Wiley
Publication Date:
2009
detail.hit.zdb_id:
2025223-7
Permalink