"Absorption spectra and photochemical reactions in a unique photoactive protein, middle rhodopsin MR"
"Absorption spectra and photochemical reactions in a unique photoactive protein, middle rhodopsin MR"
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“独特的光活性蛋白中视紫红质 MR 的吸收光谱和光化学反应”
DOI：
10.1021/jp302357m
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发表时间：
2012
期刊：
影响因子：
3.3
通讯作者：
and Y. Sudo
中科院分区：
文献类型：
--
作者：
K. Inoue;L. Reissig;M. Sakai;S. Kobayashi;M. Homma;M. Fujii;H. Kandori;and Y. Sudo
具有同源生色团的光活性蛋白广泛存在于生物体中，并作为光能转换器或光信号转导的受体。视紫红质在其七个跨膜α-螺旋内具有视黄酸（维生素A醛）作为其发色团，视紫红质被分为两类，微生物（1型）和动物（2型）视紫红质。一般来说，1型或2型视紫红质的光吸收分别触发视黄醛的反式-顺式-反式异构化，从而引发它们的光化学反应。最近，我们发现了一种新的微生物视紫红质（middle rhodopsin，MR），在其原始状态下结合三种类型的视网膜异构体：全反式，13-顺式和11-顺式。在这里，我们确定了MR的绝对吸收光谱的组合，高效液相色谱法（HPLC）和紫外-可见光谱在不同的光照条件下。MR与全反式、13-顺式或11-顺式视黄醛的最大吸收分别位于485、479和495 nm处。使用不同的激光波长，通过时间分辨激光光谱分析了它们的光循环。因此，我们提出了MR的光循环顺序分别为：MR（transs）→ MRK：寿命= 93 μs → MRM：寿命= 12 ms → MR，MR（13-cis）→ MRO-like：寿命= 5.1 ms → MR，MR（11-cis）→ MRK-like：寿命= 8.2 μs → MR。因此，我们证明了一个单一的光活性蛋白驱动三个独立的光化学反应。
Photoactive proteins with cognate chromophores are widespread in organisms, and function as light-energy converters or receptors for light-signal transduction. Rhodopsins, which have retinal (vitamin A aldehyde) as their chromophore within their seven transmembrane α-helices, are classified into two groups, microbial (type-1) and animal (type-2) rhodopsins. In general, light absorption by type-1 or type-2 rhodopsins triggers atrans–cisorcis–transisomerization of the retinal, respectively, initiating their photochemical reactions. Recently, we found a new microbial rhodopsin (middle rhodopsin, MR), binding three types of retinal isomers in its original state: all-trans, 13-cis, and 11-cis. Here, we identified the absolute absorption spectra of MR by a combination of high performance liquid chromatography (HPLC) and UV–vis spectroscopy under varying light conditions. The absorption maxima of MR with all-trans, 13-cis, or 11-cisretinal are located at 485, 479, and 495 nm, respectively. Their photocycles were analyzed by time-resolved laser spectroscopy using various laser wavelengths. In conclusion, we propose that the photocycles of MR are MR(trans) → MRK:lifetime = 93 μs → MRM:lifetime = 12 ms → MR, MR(13-cis) → MRO-like:lifetime = 5.1 ms → MR, and MR(11-cis) → MRK-like:lifetime = 8.2 μs → MR, respectively. Thus, we demonstrate that a single photoactive protein drives three independent photochemical reactions.