Prisner Thomas, Lyubenova Sevdalina, Atabay Yener, MacMillan Fraser, Kröger Achim, Klimmek Oliver
Institute of Physical and Theoretical Chemistry, Johann Wolfgang Goethe-University Frankfurt, Marie-Curie-Strasse 11, 60439, Frankfurt am Main, Germany.
J Biol Inorg Chem. 2003 Apr;8(4):419-26. doi: 10.1007/s00775-002-0432-5. Epub 2003 Jan 17.
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 Mo(V) 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 Mo(V) states, based on the experimentally observed shift of the g(av) 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 Mo(V) G-tensor supports this assignment.
首次观察到琥珀酸沃林氏菌多硫化物还原酶（Psr）中钼中心具有异常高的G张量值的电子顺磁共振（EPR）光谱。通过添加底物多硫化物和不同的氧化还原试剂产生了三种不同的Mo(V)状态，并使用多频（S波段、X波段和Q波段）连续波EPR光谱通过它们的G张量和超精细张量进行分析。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因子；通过诱变研究确定另外一个硫配体是蛋白质主链的一个半胱氨酸残基。基于实验观察到的g(av)值的位移，为其中两种Mo(V)状态提出了另一个硫配体。这个第六个硫配体被假定属于该酶催化反应循环中消耗的多硫化物底物。辅酶蛋白硫转移酶对Mo(V) G张量的影响支持了这一归属。
