Ultrafast infrared spectroscopy on channelrhodopsin-2 reveals efficient energy transfer from the retinal chromophore to the protein.
Ultrafast infrared spectroscopy on channelrhodopsin-2 reveals efficient energy transfer from the retinal chromophore to the protein.
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DOI：
10.1021/ja400554y
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发表时间：
2013-05
影响因子：
15
通讯作者：
Mirka Neumann-Verhoefen;Karsten Neumann;C. Bamann;I. Radu;J. Heberle;E. Bamberg;J. Wachtveitl
中科院分区：
文献类型：
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作者：
Mirka Neumann-Verhoefen;Karsten Neumann;C. Bamann;I. Radu;J. Heberle;E. Bamberg;J. Wachtveitl
利用飞秒可见泵浦/中红外探测光谱研究了通道视紫红质-2的初级反应动力学。由于通道视紫红质-2中激发态的快速失活，可以观察到视网膜异构化对蛋白质周围的直接影响。我们表明，在1665 cm（-1）的主要负带暂时分配给酰胺I振动的时间常数为0.5 ps的开发。在这个时间尺度上也形成或加强了各种侧链振动。通过比较80 K下通道视紫红质-2在水和D2 O中的光诱导红外光谱，初步确定了精氨酸侧链的贡献。随后观察到的几乎整个差异模式的衰减对视网膜的C C和C N伸缩振动具有特别高的影响。这表明，潜在的机制描述了一个冷却过程，其中多余的能量被重定向到视网膜周围，例如，蛋白质和功能性水分子。与其他视紫红质相比，明显的蛋白质贡献指向通道视紫红质-2中非常有效的能量再分配。
The primary reaction dynamics of channelrhodopsin-2 was investigated using femtosecond vis-pump/mid-IR probe spectroscopy. Due to the fast deactivation of the excited state in channelrhodopsin-2, it is possible to observe the direct impact of retinal isomerization on the protein surrounding. We show that the dominant negative band at 1665 cm(-1) tentatively assigned to an amide I vibration is developed with a time constant of 0.5 ps. Also a variety of side-chain vibrations are formed or intensified on this time scale. The comparison of the light-induced FT-IR spectra of channelrhodopsin-2 in H2O and D2O at 80 K enabled us to tentatively identify the contribution of Arg side chain(s). The subsequently observed decay of nearly the whole difference pattern has a particularly high impact on the C═C and C═N stretching vibrations of the retinal. This suggests that the underlying mechanism describes a cooling process in which the excess energy is redirected toward the retinal surrounding, e.g., the protein and functional water molecules. The pronounced protein contributions in comparison to other rhodopsins point to a very efficient energy redistribution in channelrhodopsin-2.