ENDOR of the resting state of nitrogenase molybdenum―iron proteins from Azotobacter vinelandii, Klebsiella pneumoniae, and Clostridium pasteurianum: 1H, 57Fe, 95Mo, and 33S studies
ENDOR of the resting state of nitrogenase molybdenum―iron proteins from Azotobacter vinelandii, Klebsiella pneumoniae, and Clostridium pasteurianum: 1H, 57Fe, 95Mo, and 33S studies
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来自固氮菌、肺炎克雷伯菌和巴氏梭菌的固氮酶钼铁蛋白静息态的 ENDOR：1H、57Fe、95Mo 和 33S 研究
DOI：
10.1021/ja00272a054
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发表时间：
1986
影响因子：
15
通讯作者：
W. Orme
中科院分区：
文献类型：
--
作者：
R. Venters;M. Nelson;P. Mclean;A. True;M. Levy;B. Hoffman;W. Orme
Electron nuclear double resonance(ENDOR) studies of native and isotopically enriched MoFe proteins hold the promise of individuallycharacterizing every atom of the catalytically active FeMo-co cluster of the nitrogenase MoFe protein. This report presents, 57Fe, 95, 97Mo, and 33S ENDOR measurements in a comparison of the MoFe protein isolated from the three titled organisms, Avl, Kpl, and Cpl. We have examined in detail single-crystal-like 57Fe resonances from at least five distinct iron sites in each of the three enzymes, revising somewhat our earlier assignments. The analysis incidentally gives the electron spin zero-field splitting parameters to high precision. 95Mo ENDOR measurements for Cpl and Kpl give 95Mo hyperfine and quadrupole coupling constants. They indicate that a single molybdenum is integrated into the MoFe spin system and that the molybdenum is most plausibly viewed as being in an even-electron state, which may be assigned provisionally as unsymmetrically coordinated MoIv. The observation of an exchangeable proton or protons from each protein source suggests a site on the cluster accessible to solvent and perhaps containing H20 or OH-. Cpl enriched in 33S gives the first observed ENDOR signals from this nucleus. The resonances from 33S are assignable to the inorganicsulfur because, it is argued, the FeMo-co cluster must be bound to the protein primarily, if not exclusively, by residues other than cysteinyl.
