Iron–sulfur proteins play essential roles in various biological processes. Their electronic structure and vibrational dynamics are key to their rich chemistry but nontrivial to unravel. Here, the first ultrafast transient absorption and impulsive coherent vibrational spectroscopic (ICVS) studies on 2Fe–2S clusters in Rhodobacter capsulatus ferreodoxin VI are characterized. Photoexcitation initiated populations on multiple excited electronic states that evolve into each other in a long-lived charge-transfer state. This suggests a potential light-induced electron-transfer pathway as well as the possibility of using iron–sulfur proteins as photosensitizers for light-dependent enzymes. A tyrosine chain near the active site suggests potential hole-transfer pathways and affirms this electron-transfer pathway. The ICVS data revealed vibrational bands at 417 and 484 cm^–1, with the latter attributed to an excited-state mode. The temperature dependence of the ICVS modes suggests that the temperature effect on protein structure or conformational heterogeneities needs to be considered during cryogenic temperature studies.

中文翻译：

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荚膜红球菌铁氧还蛋白VI铁-硫复合物中的超快电荷转移动力学

铁硫蛋白在各种生物过程中起着至关重要的作用。它们的电子结构和振动动力学是其丰富化学性质的关键，但对拆解来说却是不平凡的。在这里，首次对荚膜红细菌中的2Fe–2S团簇进行超快速瞬态吸收和脉冲相干振动光谱（ICVS）研究表征了铁氧还蛋白VI。光激发引发了在多个激发电子态上的种群，这些电子态以长寿命的电荷转移态相互演化。这表明潜在的光诱导电子转移途径，以及使用铁硫蛋白作为光敏酶的光敏剂的可能性。活性位点附近的酪氨酸链暗示了潜在的空穴转移途径，并确认了该电子转移途径。ICVS数据揭示了在417和484 cm ^–1处的振动带，后者归因于激发态模式。ICVS模式的温度依赖性表明，在低温温度研究期间需要考虑温度对蛋白质结构或构象异质性的影响。