A heterodimeric cytochrome c complex with a very low redox potential from an anaerobic ammonium-oxidizing enrichment culture
A heterodimeric cytochrome c complex with a very low redox potential from an anaerobic ammonium-oxidizing enrichment culture
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来自厌氧氨氧化富集培养物的具有极低氧化还原电位的异二聚体细胞色素 c 复合物
DOI：
10.1111/j.1574-6968.2010.02122.x
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
Furukawa K
中科院分区：
文献类型：
--
作者：
Ukita S;Fujii T;Hira D;Nishiyama T;Kawase T;Migita CT;Furukawa K
从厌氧氨氧化细菌KSU-1中大量分离到一种表观分子质量为25 kDa的二聚体细胞色素。这种蛋白质被命名为NaxLS复合体。氧化态的光谱在419 nm处有一个特殊的Soret峰。过量的二亚硫酸盐对NaxLS的还原作用不完全，但与柠檬酸钛的作用完全，表明NaxLS络合物具有很低的氧化还原电位。编码这两个亚基naxLandnaxS的基因在基因组上是相邻的。推导的氨基酸序列与斯图加特假丝酵母基因组中编码未知蛋白的两个基因有较高的同源性，但与其他C型血红素蛋白的同源性较低。NaxLS的电子顺磁共振谱显示出两个血红素物种在eng=2.6和g=1.8范围内的低自旋信号，这强烈地表明了His/Cys的不寻常配位。这种独特的配位可能解释了NaxLS中HEME的低氧化还原电位。NaxLS可能参与了低氧化还原势电子在细胞内的胞间或胞浆内的传递。
A dimeric cytochromecwith an apparent molecular mass of 25 kDa was isolated from an anammox bacterium, strain KSU-1, in a relatively large quantity. This protein was named the NaxLS complex. The spectrum of the oxidized form exhibited a peculiar Soret peak at 419 nm. The reduction of NaxLS was not complete even with the addition of excess dithionite, but was complete with titanium (III) citrate, indicating that the NaxLS complex has a very low redox potential. The genes encoding the two subunits,naxLandnaxS, are adjacent on the genome. The deduced amino-acid sequences of the genes showed high identities with those of two genes encoding ‘unknown proteins’ in the genome ofCandidatusKuenenia stuttgartiensis, but had lower identities with otherc-type heme proteins. The electron paramagnetic resonance spectra of NaxLS exhibited low-spin signals of two heme species in the range betweeng=2.6 andg=1.8, which strongly suggested an unusual His/Cys coordination. This unique coordination might account for the low redox potential of the hemes in NaxLS. NaxLS might participate in the transfer of low redox potential electrons in the intracellular anammoxosome compartment or the cytoplasm.