Khmelnitskiy Anton, Reinot Tonu, Jankowiak Ryszard
J Phys Chem Lett. 2018 Jun 21;9(12):3378-3386. doi: 10.1021/acs.jpclett.8b01396. Epub 2018 Jun 7.
Hole burning (HB) spectroscopy and modeling studies reveal significant changes in the excitonic structure and dynamics in several mutants of the FMO trimer from the Chlorobaculum tepidum. The excited-state decay times ( T) of the high-energy excitons are significantly modified when mutation occurs near bacteriochlorophyll (BChl) 1 (V152N mutant) or BChl 6 (W184F). Longer (averaged) T times of highest-energy excitons in V152N and W184F mutants suggest that site energies of BChls 1 and 6, believed to play an important role in receiving excitation from the baseplate BChls, likely play a critical role to ensure the femtosecond (fs) energy relaxation observed in wild-type FMO. HB spectroscopy reveals preferentially slower T times (about 1 ps on average) because fs times prohibit HB due to an extremely low HB quantum yield. Uncorrelated (incoherent) excitation energy transfer times between monomers, the composition of exciton states, and average, frequency-dependent, excited-state decay times ( T) are discussed.
空穴烧蚀（HB）光谱学和建模研究揭示了来自嗜热绿菌的FMO三聚体的几个突变体中激子结构和动力学的显著变化。当在细菌叶绿素（BChl）1（V152N突变体）或BChl 6（W184F）附近发生突变时，高能激子的激发态衰减时间（T）会发生显著改变。V152N和W184F突变体中最高能量激子的（平均）T时间更长，这表明BChls 1和6的位点能量，被认为在从基板BChls接收激发方面起重要作用，可能在确保野生型FMO中观察到的飞秒（fs）能量弛豫方面起关键作用。HB光谱显示优先较慢的T时间（平均约1皮秒），因为fs时间由于极低的HB量子产率而禁止HB。讨论了单体之间不相关（非相干）的激发能量转移时间、激子态的组成以及平均的、频率相关的激发态衰减时间（T）。
