Moura I, Lino A R, Moura J J, Xavier A V, Fauque G, Peck H D, LeGall J
Biochem Biophys Res Commun. 1986 Dec 30;141(3):1032-41. doi: 10.1016/s0006-291x(86)80148-6.
Two new low molecular weight proteins with sulfite reductase activity, isolated from Methanosarcina barkeri (DSM 800) and Desulfuromonas acetoxidans (strain 5071), were studied by EPR and optical spectroscopic techniques. Both proteins have visible spectra similar to that of the low-spin sulfite reductase of Desulfovibrio vulgaris strain Hildenborough and no band at 715 nm, characteristic of high-spin Fe3+ complexes in isobacteriochlorins is observed. EPR shows that as isolated the siroheme is in a low-spin ferric state (S = 1/2) with g-values at 2.40, 2.30 and 1.88 for the Methanosarcina barkeri enzyme and g-values at 2.44, 2.33 and 1.81 for the Desulfuromonas acetoxidans enzyme. Chemical analysis shows that both proteins contain one siroheme and one [Fe4S4] center per polypeptidic chain. These results suggest that the low molecular weight, low-spin non-heme iron siroheme proteins represent a new homologous class of sulfite reductases common to anaerobic microorganisms.
从巴氏甲烷八叠球菌（DSM 800）和乙酸氧化脱硫单胞菌（菌株5071）中分离出两种具有亚硫酸盐还原酶活性的新型低分子量蛋白质，采用电子顺磁共振（EPR）和光谱技术对其进行了研究。这两种蛋白质的可见光谱与希登伯勒脱硫弧菌低自旋亚硫酸盐还原酶的光谱相似，且未观察到715 nm处的吸收带，而异菌叶绿素中高自旋Fe3+配合物的特征吸收带则位于该波长处。电子顺磁共振显示，分离得到的西罗血红素处于低自旋铁（Ⅲ）状态（S = 1/2），巴氏甲烷八叠球菌酶的g值分别为2.40、2.30和1.88，乙酸氧化脱硫单胞菌酶的g值分别为2.44、2.33和1.81。化学分析表明，这两种蛋白质每条多肽链均含有一个西罗血红素和一个[Fe4S4]中心。这些结果表明，低分子量、低自旋非血红素铁西罗血红素蛋白代表了厌氧微生物中常见的一类新的同源亚硫酸盐还原酶。
