Optical and magneto-optical activity of cytochrome bd from Geobacillus thermodenitrificans
Optical and magneto-optical activity of cytochrome bd from Geobacillus thermodenitrificans
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DOI：
10.1016/j.bbabio.2012.06.009
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发表时间：
2012-11-01
影响因子：
4.3
通讯作者：
Borisov, Vitaliy B.
中科院分区：
文献类型：
--
作者：
Arutyunyan, Alexander M.;Sakamoto, Junshi;Borisov, Vitaliy B.
细胞色素BD是许多原核生物呼吸链中的末端氧化酶。它们以从对苯二酚中提取电子为代价，将O-2还原为2H(2)O。根据亚基I的跨膜螺旋6和7之间存在长或短的亲水连接，可将氧化酶分为L和S两个亚家族，称为Q环。L亚家族成员，例如来自大肠杆菌的酶，被相对较好地研究，并被证明能产生质子动力。S亚家族包括大多数细胞色素BD，包括来自热脱氮地杆菌的酶，但对该亚家族的研究很少。在室温下，我们用吸附结合的方法比较了产自嗜热嗜热菌和大肠杆菌的细胞色素BD的性质。CD和MCD光谱。尽管在吸收光谱中看不到其在595 nm处的特征Q(00)带(“α带”)，但热减氮棉酶确实含有高自旋的血红素b(HS)(“b(595)”)：建议每个酶复合体的血红素b(LS)、b(HS)和d的化学计量比为1：1：1。在1 mm CO下，热减氮棉氧化酶中20-25%的亚铁血红素(HS)与配体结合，而对于大肠杆菌酶，这样的反应很轻微。在G.thermodenitriicans氧化酶中，亚铁血红素b(HS)与d之间的激子相互作用比在E.coliBd中的激子相互作用减弱。后者可能表明，这两种酶在血红素d和血红素b(HS)之间的距离和/或它们的卟啉平面之间的夹角不同。(C)2012爱思唯尔B.V.保留所有权利。
Cytochromes bd are terminal oxidases in the respiratory chains of many prokaryotic organisms. They reduce O-2 to 2H(2)O at the expense of electrons extracted from quinol. The oxidases can be divided into two subfamilies, L and S. based on the presence of either a long or a short hydrophilic connection between transmembrane helices 6 and 7 in subunit I designated as 'Q-loop'. The L-subfamily members, e.g. the enzyme from Escherichia coli, are relatively well-studied and were shown to generate proton-motive force. The S-subfamily comprises the majority of cytochromes bd including the enzyme from Geobacillus thermodenitrificans but is very poor studied. We compared the properties of cytochromes bd from G. thermodenitrificans and E. coli at room temperature using a combination of absorption. CD and MCD spectroscopy. The G. thermodenitrificans enzyme does contain the high-spin heme b(Hs) ("b(595)") despite the fact that its characteristic Q(00)-band ("alpha-band) at 595 nm is not seen in the absorption spectra: stoichiometry of hemes b(LS), b(HS) and d per the enzyme complex is suggested to be 1:1:1. At 1 mM CO, 20-25% of ferrous heme b(HS) in the G. thermodenitrificans oxidase binds the ligand, while in case of the E. coli enzyme such a reaction is minor. In the G. thermodenitrificans oxidase, the excitonic interaction between ferrous hemes b(HS) and d decreased as compared to that in the E. coli bd. The latter may suggest that the two enzymes differ in the distance between heme d and heme b(HS) and/or in the angle between their porphyrin planes. (c) 2012 Elsevier B.V. All rights reserved.