Spectroscopic studies of bound cytochromecand an iron-sulfur center in a purified reaction center complex from the green sulfur bacteriumChlorobium tepidum

✍ Scribed by Noriaki Kusumoto; Kazuhito Inoue; Hidehiro Sakurai

• Publisher: Springer
• Year: 1995
• Tongue: English
• Weight: 489 KB
• Volume: 43
• Category: Article
• ISSN: 0166-8595
• DOI: 10.1007/bf00042967

✦ Synopsis

Flash-induced optical kinetics at room temperature ofcytochrome (Cyt) CSsl and an Fe-S center (CFA/CFB) bound to a purified reaction center (RC) complex from the green sulfur photosynthetic bacterium Chlorobium tepidum were studied. At 551 nm, the flash-induced absorbance change decayed with a tl/2 of several hundred ms, and the decay was accelerated by 1-methoxy-5-methylphenazinium methyl sulfate (mPMS). In the blue region, the absorbance change was composed of mPMS-dependent (Cyt) and mPMS-independent component (CFA/CFB) which decayed with a h/2 of ,-~400-650 ms. Decay of the latter was effectively accelerated by benzyl viologen (Em -3 6 0 mV) and methyl viologen ( -4 4 0 mV), and less effectively by triquat (-540 mV). The difference spectrum of Cyt c had negative peaks at 551, ,,~520 and ,,~420 nm, with a positive rise at ,,~440 to ,-~500 nm. The difference spectrum of CFA/CFB resembled P430 of PSI, and had a broad negative peak at 430,,~435 nm.