Document Detail

Influence of "alternative" C-terminal amino acids on the formation of [b3 + 17 + Cat]+ products from metal cationized synthetic tetrapeptides.
MedLine Citation:
PMID:  15170745     Owner:  NLM     Status:  MEDLINE    
The aim of this study was to investigate the dissociation patterns, and in particular the relative abundance of [b(3) + 17 + Cat](+), for peptides with C-termini designed to allow transfer of the -OH required to generate the product ion, but not necessarily as the most favored pathway. Working with the hypothesis that formation of a five-membered ring intermediate, including intramolecular nucleophilic attack by a carbonyl oxygen atom, is an important mechanistic step, several model peptides with general sequence AcFGGX were synthesized, metal cationized by electrospray ionization and subjected to collision-induced dissociation (CID). The amino acid at position X was one that either required a larger ring intermediate (beta-alanine, gamma-aminobutyric acid and epsilon-amino-n-caproic acid to generate six-, seven- or nine- membered rings, respectively) to transfer -OH, lacked a structural element required for nucleophilic attack (aminoethanol) or prohibited cyclization because of the inclusion of a rigid ring (p- and m-aminobenzoic acid). For Ag(+), Li(+) and Na(+) cationized peptides, our results show that amino acids requiring the adoption of larger ring intermediates suppressed the formation of [b(3) + 17 + Cat](+), while amino acids that prohibit cyclization eliminated the reaction pathway completely. Formation of [b(3) - 1 + Cat](+) from the alkali metal cationized versions was not a favorable process upon suppression or elimination of the [b(3) + 17 + Cat](+) pathway: the loss of H(2)O to form [M - H(2)O + Cat](+) was instead the dominant dissociation reaction observed. Multiple-stage dissociation experiments suggest that [M - H(2)O + Cat](+) is not [b(4) - 1 + Cat](+) arising from the loss of H(2)O from the C-terminus, but may instead be a species that forms via a mechanism involving the elimination of an oxygen atom from an amide group.
V Anbalagan; A T M Silva; S Rajagopalachary; K Bulleigh; E R Talaty; M J Van Stipdonk
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of mass spectrometry : JMS     Volume:  39     ISSN:  1076-5174     ISO Abbreviation:  J Mass Spectrom     Publication Date:  2004 May 
Date Detail:
Created Date:  2004-06-01     Completed Date:  2004-06-18     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9504818     Medline TA:  J Mass Spectrom     Country:  England    
Other Details:
Languages:  eng     Pagination:  495-504     Citation Subset:  IM    
Copyright Information:
Copyright 2004 John Wiley & Sons, Ltd.
Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, USA.
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MeSH Terms
Amino Acids / chemistry*
Cations / chemistry
Mass Spectrometry
Metals / chemistry*
Molecular Structure
Oligopeptides / chemical synthesis,  chemistry*
Reg. No./Substance:
0/Amino Acids; 0/Cations; 0/Metals; 0/Oligopeptides

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