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首页> 外文期刊>Biochemistry >VIBRATIONAL DEPHASING OF LONG- AND SHORT-LIVED PRIMARY DONOR EXCITED STATES IN MUTANT REACTION CENTERS OF RHODOBACTER SPHAEROIDES
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VIBRATIONAL DEPHASING OF LONG- AND SHORT-LIVED PRIMARY DONOR EXCITED STATES IN MUTANT REACTION CENTERS OF RHODOBACTER SPHAEROIDES

机译：球形红细菌突变反应中心中长寿命和短寿命供体激发态的振动脱色

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摘要

Femtosecond spectroscopy was used to study vibrational dynamics in the first singlet excited state (P*) of the primary donor of bacterial reaction centers (RC) in which primary electron transfer dynamics have been altered by single amino acid modifications. We studied intracytoplasmic RC-only membranes containing Rhodobacter sphaeroides wild-type RCs and RCs bearing mutations in the vicinity of P, where Tyr M210 was modified to His, Leu, and Trp and where Phe L181 was modified to Tyr. These mutations do not change the frequencies of the main low-frequency activated modes, which is consistent with a description in which these modes involve extended regions of the protein. Electron transfer in FL181Y, YM210H, and wild-type RCs at 10 K occurs in similar to 1 ps or less, and the damping of the coherences occurs simultaneously with the decay of the P* excited state. These results, and a comparison with YM210L RCs, show that in wild-type RCs the damping is primarily determined by the depletion of P* and not by vibrational dephasing induced by interactions with the bath or nonharmonic coupling. In the YM210L and W mutants, electron transfer occurs on a time scale of hundreds of picoseconds at 10 K. Analysis of the longer-lasting vibrational dynamics in these mutants sets a new lower limit for the intrinsic vibrational dephasing time of 1,2 ps for some modes, but of similar to 2 ps for most activated modes.
机译：飞秒光谱法用于研究细菌反应中心（RC）的主要供体的第一单重态激发态（P *）的振动动力学，在该反应态中，主要电子传递动力学已通过单个氨基酸修饰而改变。我们研究了胞内仅含RC的膜，其中包含球形红球菌野生型RC和在P附近突变的RC，其中Tyr M210修饰为His，Leu和Trp，Phe L181修饰为Tyr。这些突变不会改变主要的低频激活模式的频率，这与其中这些模式涉及蛋白质的延伸区域的描述是一致的。 FL181Y，YM210H和野生型RC在10 K时的电子传输以大约1 ps或更小的速度发生，并且相干的衰减与P *激发态的衰减同时发生。这些结果以及与YM210L RC的比较表明，在野生型RC中，阻尼主要由P *的损耗决定，而不是由与水浴相互作用或非谐波耦合引起的振动移相决定。在YM210L和W突变体中，电子转移发生在10 K时数百皮秒的时间尺度上。对这些突变体中更长的振动动力学的分析为1,2 ps的固有振动移相时间设定了新的下限，即1,2 ps。某些模式，但对于大多数激活模式而言，类似于2 ps。

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