Spectroscopic studies of bound cytochrome c and an iron-sulfur center in a purified reaction center complex from the green sulfur bacterium Chlorobium tepidum

Noriaki Kusumoto, Kazuhito Inoue, Hidehiro Sakurai

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Abstract

Flash-induced optical kinetics at room temperature of cytochrome (Cyt) c551 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 t1/2 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 t1/2 of ∼400-650 ms. Decay of the latter was effectively accelerated by benzyl viologen (Em -360 mV) and methyl viologen (-440 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.

Original languageEnglish
Pages (from-to)107-112
Number of pages6
JournalPhotosynthesis Research
Volume43
Issue number2
DOIs
Publication statusPublished - 1995 Feb 1

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Keywords

  • Chlorobium tepidum
  • cytochrome c
  • electron transfer
  • flash photolysis spectroscopy
  • iron-sulfur center
  • reaction center

ASJC Scopus subject areas

  • Biochemistry
  • Plant Science
  • Cell Biology

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