Multifrequency cw-EPR investigation of the catalytic molybdenum cofactor of polysulfide reductase from Wolinella succinogenes
Multifrequency cw-EPR investigation of the catalytic molybdenum cofactor of polysulfide reductase from Wolinella succinogenes
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Wolinella succinogenes 多硫化物还原酶催化钼辅因子的多频连续 EPR 研究
DOI：
10.1007/s00775-002-0432-5
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
O. Klimmek
中科院分区：
文献类型：
--
作者：
T. Prisner;Sevdalina Lyubenova;Yener Atabay;F. MacMillan;A. Kröger;O. Klimmek
首次观测到产琥珀酸狼菌具有异常高的G张量值的多硫化物还原酶(PSR)中钼中心的电子顺磁共振(EPR)谱。通过添加底物多硫化物和不同的氧化还原剂，产生了三种不同的MOV态，并用多频(S、X和Q波段)CW-EPR谱分析了它们的G-和超精细张量。异常高的G张量值归因于大量的硫配体。四个硫配体被认为来自两个蝶呤辅助因子；另一个硫配体从诱变研究中被鉴定为蛋白质骨架的半胱氨酸残基。根据实验观察到的Gav值的移动，提出了两个MOV态的另一个硫配体。这第六个硫配体被推测属于酶的催化反应周期中消耗的多硫化物底物。辅蛋白硫转移酶对MOV G张量的影响支持这一观点。
Electron paramagnetic resonance (EPR) spectra of the molybdenum centre in polysulfide reductase (Psr) from Wolinella succinogenes with unusually high G-tensor values have been observed for the first time. Three different MoV states have been generated (by the addition of the substrate polysulfide and different redox agents) and analysed by their G- and hyperfine tensors using multifrequency (S-, X- and Q-band) cw-EPR spectroscopy. The unusually high G-tensor values are attributed to a large number of sulfur ligands. Four sulfur ligands are assumed to arise from two pterin cofactors; one additional sulfur ligand was identified from mutagenesis studies to be a cysteine residue of the protein backbone. One further sulfur ligand is proposed for two of the MoV states, based on the experimentally observed shift of the gav value. This sixth sulfur ligand is postulated to belong to the polysulfide substrate consumed within the catalytic reaction cycle of the enzyme. The influence of the co-protein sulfur transferase on the MoV G-tensor supports this assignment.