Characterization of Histidine Coordination in VO2+-Substituted D-Xylose Isomerase by Orientationally-Selected Electron Spin-Echo Envelope Modulation Spectroscopy

Sergei A. Dikanov, Alexei M. Tyryshkin, Jürgen Hüttermann, Ralf Bogumil, Herbert Witzel

Research output: Contribution to journalArticlepeer-review


An orientationally-selected electron spin-echo envelope modulation (ESEEM) spectroscopy investigation was performed on VO2+introduced into the high-affinity metal-binding site of D-xylose isomerase. The ESEEM spectra clearly reveal the presence of nitrogen ligands with hyperfine coupling AN≈ 6 MHz. Detailed analysis includes first- and second-order treatment of the nitrogen basic and combination harmonics in two-pulse ESEEM spectra of the g||and gcomponents. Complete determination of the hyperfine and quadrupole tensor indicates equatorial coordination of the imine nitrogen of the histidine residue. The presence of Cd2+ion in the second, low-affinity metal-binding site does not affect the nitrogen couplings. The protons surrounding the VO2+ion have been examined via the proton sum combinations in four-pulse ESEEM. They demonstrate the contribution of two protons probably belonging to the histidine ligand. These investigations strongly support the further application of VO2+as a spin probe in conjunction with ESEEM spectroscopy for detailed investigation of nitrogen ligands in the active metal sites of proteins.

Original languageEnglish (US)
Pages (from-to)4976-4986
Number of pages11
JournalJournal of the American Chemical Society
Issue number17
StatePublished - May 1995
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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