A new pathway in the photoreaction cycle of trans-bacteriorhodopsin and the absorption spectra of its intermediates
A new pathway in the photoreaction cycle of trans-bacteriorhodopsin and the absorption spectra of its intermediates
复制标题
反式细菌视紫红质光反应循环的新途径及其中间体的吸收光谱
DOI：
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发表时间：
1980
期刊：
影响因子：
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通讯作者：
T. Yoshizawa
中科院分区：
文献类型：
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作者：
T. Iwasa;F. Tokunaga;T. Yoshizawa
在两种不同的条件下研究了光反应循环中反式细菌视紫红质（trans-bR）的中间体。在低盐和中性 pH 介质（10 mM 磷酸盐缓冲液，pH 6.6）中，在 -190‡ C 下用 500 nm 光照射 trans-bR，形成 Batho-trans-bR (batho-bRt)。在黑暗中升温时，batho-bRt 转化为 lumi-trans-bR (lumi-bRt)、meta-trans-bR (meta-bRt)，最后转化为 trans-bR。没有观察到其他人通过闪光光解检测到的中间体N和O。 lumi-bRt 在高盐和高 pH 介质（10 mM 硼酸盐缓冲液和 1 M NaCl，pH 10.0）中的热衰变通过两条途径同时进行；一个连接到meta-bRt，另一个连接到trans-bR。大约72%的lumi-bRt直接转化为反式-bR，残余物转化为meta-bRt。利用该值，计算batho-bRt(λmax：626nm)、lumi-bRt(λmax：543nm)和meta-bRt(λmax：418nm)的吸收光谱。基于上述发现提出了细菌视紫红质的光反应循环。
The intermediates of trans-bacteriorhodopsin (trans-bR) in the photoreaction cycle were investigated under two different conditions. In a low salt and neutral pH medium (10 mM phosphate buffer, pH 6.6), trans-bR was irradiated with 500 nm light at −190‡ C, resulting in formation of batho-trans-bR (batho-bRt). On warming in the dark, batho-bRt converted to lumi-trans-bR (lumi-bRt), meta-trans-bR (meta-bRt) and finally to trans-bR. The intermediates N and O, which had been detected by others by flash photolysis, were not observed. The thermal decay of lumi-bRt in a high salt and high pH medium (10 mM borate buffer with l M NaCl, pH 10.0) proceeded simultaneously through two pathways; one to meta-bRt and another to trans-bR. About 72% of lumi-bRt converted to trans-bR directly and the residue converted to meta-bRt. By use of this value, the absorption spectra of batho-bRt (λmax: 626 nm), lumi-bRt (λmax: 543 nm) and meta-bRt (λmax: 418 nm) were calculated. A photoreaction cycle of bacteriorhodopsin was proposed on the basis of the above findings.