Pulsed proton-deuterium 1, 2H ENDOR and 2H-2H TRIPLE resonance of H-bonds and cysteinyl β-CH2 of the D. gigas hydrogenase [3Fe-4S]+ cluster

Peter E. Doan, Chaoliang Fan, Brian M. Hoffman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

This paper presents the results of 2H Mims and 1H Davies pulsed ENDOR of the [3Fe-4S]+ cluster of Desulfovibrio gigas hydrogenase. It also describes the first 2H Mims pulsed TRIPLE-resonance experiments, on the exchangeable deuterons. The 1H ENDOR data show that the intrinsic isotropic hyperfine couplings for the β-CH2protons of the three cysteines bound to iron fall in the range 1.3 ≲ a ≲ 1.9 MHz. These values, which often had been estimated at a = 1 MHz, will allow better interpretation of solution NMR data for paramagnetic [nFe-wS] clusters. The spectra show well-resolved signals from three strong NH…S H-bonds to the cluster. Mims 2H-2H TRIPLE-resonance has been used to assign the exchangeable deuterons and to obtain relative signs of the 1, 2H hyperfine couplings. Analysis of the hyperfine interactions in terms of spin-coupling among the three Fe(III) ions of the cluster, along with examination of the X-ray structures of several [3Fe-4S]+ clusters, gives an intrinsic hyperfine coupling of a(1H) ~ 3-4 MHz for each of the three strong H-bonds and actually allows us to propose the distribution of H-bonds among the seven sulfur atoms within the [Fe3S4(Cys)3]2- center.

Original languageEnglish (US)
Pages (from-to)1033-1041
Number of pages9
JournalJournal of the American Chemical Society
Volume116
Issue number3
DOIs
StatePublished - Feb 1 1994

ASJC Scopus subject areas

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

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