Kamlage B, Blaut M
Institut für Mikrobiologie, Georg-August-Universität Göttingen, Germany.
J Bacteriol. 1992 Jun;174(12):3921-7. doi: 10.1128/jb.174.12.3921-3927.1992.
Methanosarcina strain Gö1 was tested for the presence of cytochromes. Low-temperature spectroscopy, hemochrome derivative spectroscopy, and redox titration revealed the presence of two b-type (b559 and b564) and two c-type (c547 and c552) cytochromes in membranes from Methanosarcina strain Gö1. The midpoint potentials determined were Em,7 = -135 +/- 5 and -240 +/- 11 mV (b-type cytochromes) and Em,7 = -140 +/- 10 and -230 +/- 10 mV (c-type cytochromes). The protoheme IX and the heme c contents were 0.21 to 0.24 and 0.09 to 0.28 mumol/g of membrane protein, respectively. No cytochromes were detectable in the cytoplasmic fraction. Of various electron donors and acceptors tested, only the reduced form of coenzyme F420 (coenzyme F420H2) and the heterodisulfide of coenzyme M and 7-mercaptoheptanoylthreonine phosphate (CoM-S-S-HTP) were capable of reducing and oxidizing the cytochromes at a high rate, respectively. Addition of CoM-S-S-HTP to reduced cytochromes and subsequent low-temperature spectroscopy revealed the oxidation of cytochrome b564. On the basis of these results, we suggest that one or several cytochromes participate in the coenzyme F420H2-dependent reduction of the heterodisulfide.
对甲烷八叠球菌菌株Gö1进行了细胞色素检测。低温光谱法、血红素衍生物光谱法和氧化还原滴定法显示，甲烷八叠球菌菌株Gö1的细胞膜中存在两种b型细胞色素（b559和b564）和两种c型细胞色素（c547和c552）。测定的中点电位为Em,7 = -135 ± 5和-240 ± 11 mV（b型细胞色素）以及Em,7 = -140 ± 10和-230 ± 10 mV（c型细胞色素）。原卟啉IX和细胞色素c的含量分别为0.21至0.24和0.09至0.28 μmol/g膜蛋白。在细胞质部分未检测到细胞色素。在测试的各种电子供体和受体中，只有还原型辅酶F420（辅酶F420H2）以及辅酶M和7-巯基庚酰苏氨酸磷酸的异二硫化物（CoM-S-S-HTP）分别能够高速还原和氧化细胞色素。向还原的细胞色素中添加CoM-S-S-HTP并随后进行低温光谱分析，结果显示细胞色素b564被氧化。基于这些结果，我们认为一种或几种细胞色素参与了辅酶F420H2依赖的异二硫化物还原反应。
