Formation of the early photoproduct Lumi-R of cyanobacterial phytochrome Cph1 observed by ultrafast mid-infrared spectroscopy
Formation of the early photoproduct Lumi-R of cyanobacterial phytochrome Cph1 observed by ultrafast mid-infrared spectroscopy
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DOI：
10.1021/ja0660709
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发表时间：
2007-01-10
影响因子：
15
通讯作者：
Towrie, Michael
中科院分区：
文献类型：
--
作者：
van Thor, Jasper J.;Ronayne, Kate L.;Towrie, Michael
用皮秒时间分辨中红外光谱研究了聚球藻PCC6803蓝藻光敏色素Cph1的Pr基态在室温下的光反应。在640 nm的Pr态的飞秒激发下，产生了光致异构化Lumi-R产物态，动力学和相关的差谱表明振动冷却的时间常数为tau(1)=3ps，激发态衰减的时间常数为tau(1)=3ps，tau(2)=14ps，tau(3)=134ps。除了下移的C-19=O模之外，Lumi-R态的特征是分配给C-15=C-16、C-4=C-5的三个C=C模的下移吸收，以及一个离域的C=C模。Lumi-R减去Pr差谱表明发色团在超快时间尺度上的全局重组，除了C-5附近的变化外，还结合C-15Z/E光异构化进行了讨论，这可能是低键级扭转角度的变化。
The photoreactions of the Pr ground state of cyanobacterial phytochrome Cph1 from Synechocystis PCC 6803 have been investigated by picosecond time-resolved mid-infrared spectroscopy at ambient temperature. With femtosecond excitation of the Pr state at 640 nm, the photoisomerized Lumi-R product state is generated with kinetics and associated difference spectra indicative of vibrational cooling with tau(1) = 3 ps time constant and excited state decay with tau(1) = 3 ps, tau(2) = 14 ps, and tau(3) = 134 ps time constants. The Lumi-R state is characterized by downshifted absorption of three C=C modes assigned to C-15=C-16, C-4=C-5, and a delocalized C=C mode, in addition to the downshifted C-19=O mode. The Lumi-R minus Pr difference spectrum is indicative of global restructuring of the chromophore on the ultrafast timescale, which is discussed in light of C-15 Z/E photoisomerization in addition to changes near C-5, which could be low bond order torsional angle changes.