Document Detail

Further studies on the fragmentation of protonated ions of peptides containing aspartic acid, glutamic acid, cysteine sulfinic acid, and cysteine sulfonic acid.
MedLine Citation:
PMID:  15570570     Owner:  NLM     Status:  MEDLINE    
Here we examined the fragmentation, on a quadrupole ion-trap mass spectrometer, of the protonated ions of a group of peptides containing one arginine and two different acidic amino acids, one being aspartic acid (Asp) or glutamic acid (Glu) and the other being cysteine sulfinic acid [C(SO2H)] or cysteine sulfonic acid [C(SO3H)]. Our results showed that, upon collisional activation, the cleavage of the peptide bond C-terminal to C(SO2H) is much more facile than that of the peptide bond C-terminal to Asp, Glu, or C(SO3H). There is no significant difference, however, in susceptibility to cleavage of peptide bonds that are C-terminal to Asp, Glu, and C(SO3H). To understand these experimental observations, we carried out B3LYP/6-31G* density functional theory calculations for a model cleavage reaction of GXG --> b2 + Gly, in which X is Asp, Glu, C(SO2H), or C(SO3H). Our calculation results showed that the cleavage reaction is thermodynamically more favorable when X = C(SO2H) than when X = Asp or C(SO3H). We attributed the less facile cleavage of the amide bond after Glu to that the formation of a six-membered ring b ion for Glu-bearing peptides is kinetically not as favorable as the formation of a five-membered ring b ion for peptides containing the other three acidic amino acids. The results from this study may provide useful tools for peptide sequencing.
Lijie Men; Yinsheng Wang
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Rapid communications in mass spectrometry : RCM     Volume:  19     ISSN:  0951-4198     ISO Abbreviation:  Rapid Commun. Mass Spectrom.     Publication Date:  2005  
Date Detail:
Created Date:  2004-12-20     Completed Date:  2005-03-07     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8802365     Medline TA:  Rapid Commun Mass Spectrom     Country:  England    
Other Details:
Languages:  eng     Pagination:  23-30     Citation Subset:  IM    
Department of Chemistry-027, University of California, Riverside, CA 92521-0403, USA.
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MeSH Terms
Amino Acid Sequence
Aspartic Acid / analysis*
Cysteine / analogs & derivatives*,  analysis*
Glutamic Acid / analysis*
Oligopeptides / chemistry
Peptides / chemistry*
Spectrometry, Mass, Electrospray Ionization
Sulfonic Acids / analysis*
Reg. No./Substance:
0/Oligopeptides; 0/Peptides; 0/Sulfonic Acids; 2381-08-0/cysteine sulfinic acid; 52-90-4/Cysteine; 56-84-8/Aspartic Acid; 56-86-0/Glutamic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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