Document Detail

Gas phase H/D exchange of sodiated amino acids: why do we see zwitterions?
MedLine Citation:
PMID:  16352438     Owner:  NLM     Status:  MEDLINE    
The gas-phase interaction of sodiated amino acids and sodiated amino acid methyl esters with various deuterium donors is investigated by combining results of H/D exchange reactions with those from density functional theory and molecular dynamics calculations. Discrepancy between experimentally and theoretically obtained structures for sodium cationized amino acids is explained by deuterium donor caused perturbation of the most stable amino acid conformation. Detailed study of H/D exchange mechanism on sodiated amino acids shows that the H/D exchange reaction is preceded by a multistep quasi-isoenergetic transition (perturbation) from a charge solvated to zwitterionic structure in the amino acid. Although the computation refers to the system AlaNa(+) and D(2)O, these mechanisms apply to all amino acids, except those where a functional side-chain group takes part in the perturbation process. The suggested perturbation mechanism applies also for other deuterium donors such as CD(3)OD or even ND(3) and indicates that a single water molecule suffices to convert the sodiated amino acid from charge solvated to zwitterionic form.
Marko Rozman; Branimir Bertosa; Leo Klasinc; Dunja Srzic
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-12-15
Journal Detail:
Title:  Journal of the American Society for Mass Spectrometry     Volume:  17     ISSN:  1044-0305     ISO Abbreviation:  J. Am. Soc. Mass Spectrom.     Publication Date:  2006 Jan 
Date Detail:
Created Date:  2006-01-09     Completed Date:  2006-03-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9010412     Medline TA:  J Am Soc Mass Spectrom     Country:  United States    
Other Details:
Languages:  eng     Pagination:  29-36     Citation Subset:  IM    
Ruder Bosković Institute, Zagreb, Croatia.
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MeSH Terms
Amino Acids / chemistry*
Computer Simulation
Deuterium / chemistry
Models, Molecular
Molecular Conformation
Sodium / chemistry*
Water / chemistry
Reg. No./Substance:
0/Amino Acids; 7440-23-5/Sodium; 7732-18-5/Water; 7782-39-0/Deuterium

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

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