The search for stable gas phase b(1) ions derived from aliphatic amino acids: a combined experimental and ab initio study
Author(s)
O'Hair, RAJ; Reid, GE;
Details
Publication Year 2000, Volume 14, Issue #14, Page 1220-1225
Journal Title
RAPID COMMUNICATIONS IN MASS SPECTROMETRY
Publication Type
Journal Article
Abstract
Several previous studies have shown that b(1) ions (formally acylium ions, H2NCHRCO+) derived from protonated aliphatic amino acids are unstable in the gas phase, fragmenting via decarbonylation to form a(1) ions (iminium ions, H2N = CHR+). Herein we examine the fragmentation reactions of ten potential b(1) ion precursors to determine whether stable aliphatic b(1) ions can be formed in the gas phase. Of all the systems studied, only the aziridine b(1) ion and the dehydroalanine b(1) ion were found to be stable. These experimental results are entirely consistent with ab initio calculations (at the MP2(full)/6-311G** level) which indicate that while the loss of CO from the b(1) ion of glycine is barrierless and exoethermic, the related losses from the b(1) ions of aziridine and dehydroalanine have significant barriers (29.5 and 16.2 kcal mol(-1), respectively) and are endothermic overall. Copyright (C) 2000 John Wiley & Sons, Ltd.
Publisher
JOHN WILEY & SONS LTD
Keywords
TANDEM MASS-SPECTROMETRY; PROTONATED GLYCINE; PEPTIDE SPECTRA; CHEMISTRY; REGIOSELECTIVITY; CARBOCATIONS; DERIVATIVES; LACTAMS
Rights Notice
Refer to copyright notice on published article.


Creation Date: 2000-01-01 12:00:00
Last Modified: 0001-01-01 12:00:00
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