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Resonance Raman studies of the [4Fe‐4S] to [2Fe‐2S] cluster conversion in the iron protein of nitrogenase
Author(s) -
Fu Weiguang,
Morgan T.Vance,
Mortenson Leonard E.,
Johnson Michael K.
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)80676-t
Subject(s) - nitrogenase , raman spectroscopy , chemistry , cluster (spacecraft) , biochemistry , nitrogen fixation , organic chemistry , physics , computer science , nitrogen , optics , programming language
Resonance Raman spectroscopy has been used to investigate the Fe‐S stretching modes of the [4Fe‐4S] 2+ cluster in the oxidized iron protein of Clostridium pasteurianum nitrogenase. The results are consistent with a cubane [4Fe‐4S] cluster having effective T d symmetry with cysteinyl coordination for each iron. In accord with previous optical and EPR studies [(1984) Biochemistry 23, 2118–2122], treatment with the iron chelator α,α′‐dipyridyl in the presence of MgATP is shown to effect cluster conversion to a [2Fe‐2S] 2+ cluster. Resonance Raman data also indicate that partial conversion to a [2Fe‐2S] 2+ cluster is induced by thionine‐oxidation in the presence of MgATP in the absence of an iron chelator. This result suggests new explanations for the dramatic change in the CD spectrum that accompanies MgATP‐binding to the oxidized Fe protein and the anomalous resonance Raman spectra of thionine‐oxidized Clostridium pasteurianum bidirectional hydrogenase.