Investigation of S-H bonds in biologically important compounds by sulfur K-edge X-ray absorption spectroscopy

  • A. Prange
  • C. Dahl
  • H.G. Trüper
  • M. Behnke
  • J. Hahn
  • H. Modrow
  • J. Hormes

Abstract:

X-ray Absorption Near Edge Structure (XANES) spectroscopy, often provides a direct correlation between observed resonances in the spectrum and molecular bonds in the sample. This can be used as a fingerprint for the presence of a given molecular environment of the absorber atom in a sample. As the white line is found at similar energy positions for S-C and S-H bonds, this approach is impossible when both types of bond are present simultaneously, as often in biological systems. To develop a criterium for the presence of S-H bonds in such samples, reduced glutathione, reduced coenzyme A, cysteine and their corresponding oxidized forms were investigated using sulfur K-edge XANES, revealing a unique feature at 2 475.8 eV in the respective difference spectra. To correlate this structure to S-H bonds, H2S and H2S2 were measured, whose difference spectrum also shows a structure at this energy position, whereas it is not present throughout a variety of C-S-C/C-S-S-C environments. Theoretical investigations suggest its correlation to a Rydberg transition occurring in the case of a S-H bond. Using this criterium, the presence of S-H bonds is in the purple sulfur bacterium Allochromatium vinosum during oxidation of intracellular accumulated sulfur, is proved, as expected from biological considerations.

PACS. 87.15.By Structure and bonding – 87.64.Fb EXAFS spectroscopy – 61.10.Ht X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc. 

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Copyright information

© EDP Sciences, Springer-Verlag, Società Italiana di Fisica 2002

Authors and Affiliations

  • A. Prange
    • 1
  • C. Dahl
    • 1
  • H.G. Trüper
    • 1
  • M. Behnke
    • 2
  • J. Hahn
    • 2
  • H. Modrow
    • 3
  • J. Hormes
    • 3
  1. 1.Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Meckenheimer Allee 168, 53115 Bonn, GermanyDE
  2. 2.Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 Köln, GermanyDE
  3. 3.Physikalisches Institut, Rheinische Friedrich-Wilhelms-Universität Bonn, Nußallee 12, 53115 Bonn, GermanyDE

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