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Structure of the Ni sites in hydrogenases by x-ray absorption spectroscopy. Species variation and the effects of redox poise

Journal Article · · Journal of the American Chemical Society
DOI:https://doi.org/10.1021/ja962429p· OSTI ID:426240
; ; ;  [1]
  1. Univ. of Massachusetts, Amherst, MA (United States); and others
Structural information obtained from the analysis of nickel K-edge X-ray absorption spectroscopic data of [NiFe]hydrogenases from Desulfovibrio gigas, Thiocapsa roseopersicina, Desulfovibrio desulfuricans (ATCC 27774), Escherichia coli (hydrogenase-1), Chromatium vinosum, and Alcaligenes eutrophus H16 (NAD{sup +}-reducing, soluble hydrogenase), poised in different redox states, is reported. The data allow the active-site structures of enzymes from several species to be compared, and allow the effects of redox poise on the structure of the nickel sites to be examined. In addition, the structure of the nickel site obtained from recent crystallographic studies of the D. gigas enzyme is compared with the structural features obtained from the analysis of XAS data from the same enzyme. The nickel sites of all but the oxidized (as isolated) sample of A. eutrophus hydrogenase are quite similar. Analysis of the XANES features assigned to 1s {yields} 3d electronic transitions indicates that the shift in energy that occurs for reduction of the enzymes to the SI level may be attributed at least in part to an increase in the coordination number from five to six. The results of EXAFS analysis are shown to be in general agreement with the published crystal structure of the D. gigas enzyme. 42 refs., 6 figs., 2 tabs.
OSTI ID:
426240
Journal Information:
Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 45 Vol. 118; ISSN JACSAT; ISSN 0002-7863
Country of Publication:
United States
Language:
English