Electrochromic Detection of a Coherent Component in the Formation of the Charge Pair P+HL- in Bacterial Reaction Centers

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• 作者：Marten H. Vos ; Christian Rischel ; Michael R. Jones ; and Jean-Louis Martin
• 刊名：Biochemistry
• 出版年：2000
• 出版时间：July 25, 2000
• 年：2000
• 卷：39
• 期：29
• 页码：8353 - 8361
• 全文大小：200K
• 年卷期：v.39,no.29(July 25, 2000)
• ISSN：1520-4995

文摘

We demonstrate coupling of an intraprotein electron transfer reaction to coherent vibrationalmotions. The kinetics of charge separation toward the radical pair state P⁺H_L^- were studied in reactioncenters of Rhodobacter sphaeroides at 15 K. The electrochromic shift of the bacteriochlorophyll monomersis the most prominent spectral feature associated with this charge displacement. The newly reported absoluteabsorption spectrum of the P⁺H_L^- state is discussed in terms of this shift. In wild-type reaction centers,the rise kinetics of the electrochromic shift display a small but significant 30 cm^-1 periodic modulation(period of ~1 ps). This modulation is also present in FL181Y mutant reaction centers, where overallcharge separation is somewhat more rapid than in the wild-type reaction center. In contrast, in YM210Lmutant reaction centers, where the charge separation is much slower, the modulation is absent. Theconclusion that the motion along the reaction coordinate has a 30 cm^-1 coherent component is discussedin light of possible mechanisms of electron transfer.