Document Detail


Gas-phase IR spectroscopy of deprotonated amino acids.
MedLine Citation:
PMID:  19267428     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Gas-phase infrared multiple photon dissociation (IRMPD) spectra have been recorded for the conjugate bases of a series of amino acids (Asp, Cys, Glu, Phe, Ser, Trp, Tyr). The spectra are dominated by strong symmetric and antisymmetric carboxylate stretching modes around 1300 and 1600 cm(-1), respectively. Comparison of the experimental spectra with spectra calculated at the DFT level suggests a carboxylate structure for all species investigated, which is in contrast with what has recently been suggested in this journal for deprotonated cysteine [J. Am. Chem. Soc. 2007, 129, 5403-5407]. In addition, the IR spectrum of the conjugate base of tyrosine is also unambiguously that of a carboxylate ion and not that of a phenoxide ion. In sharp contrast with the conjugate bases of other amino acids investigated here, the aspartate and glutamate anions show very broad, hardly resolved spectral features. We present qualitative experimental evidence indicating that this can be attributed to the formation of a proton bridge between the backbone and side chain carboxylate groups. The large amplitude motion of this shared proton, coupling to virtually all other vibrational modes, causes extensive spectral broadening.
Authors:
Jos Oomens; Jeffrey D Steill; Britta Redlich
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  131     ISSN:  1520-5126     ISO Abbreviation:  J. Am. Chem. Soc.     Publication Date:  2009 Apr 
Date Detail:
Created Date:  2009-03-25     Completed Date:  2009-07-28     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4310-9     Citation Subset:  IM    
Affiliation:
FOM Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, 3439MN Nieuwegein, The Netherlands. joso@rijnhuizen.nl
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MeSH Terms
Descriptor/Qualifier:
Amino Acids / chemistry*
Anions
Aspartic Acid / chemistry
Cysteine / chemistry
Gases
Glutamic Acid / chemistry
Phenylalanine / chemistry
Protons
Serine / chemistry
Spectrophotometry / methods
Spectrophotometry, Infrared / methods*
Tyrosine / chemistry
Chemical
Reg. No./Substance:
0/Amino Acids; 0/Anions; 0/Gases; 0/Protons; 52-90-4/Cysteine; 55520-40-6/Tyrosine; 56-45-1/Serine; 56-84-8/Aspartic Acid; 56-86-0/Glutamic Acid; 63-91-2/Phenylalanine

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


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