Thermal recovery of iodopsin from photobleaching intermediates
Thermal recovery of iodopsin from photobleaching intermediates
复制标题
DOI：
10.1111/j.1751-1097.2008.00332.x
复制
发表时间：
2008-07-01
影响因子：
3.3
通讯作者：
Shichida, Yoshinori
中科院分区：
文献类型：
--
作者：
Imamoto, Yasushi;Shichida, Yoshinori
本文用时间分辨低温光谱技术在-40 ℃ ~-10 ℃温度范围内详细研究了氯离子对鸡红敏感视锥细胞色素碘视蛋白光漂白过程的影响。采用奇异值分解法进行动力学分析获得的衰变相关差谱由BL-碘视素、光碘视素、偏碘视素I、偏碘视素II和偏碘视素III的光谱组成，与室温下的光谱基本相同。然而，在每个转化步骤中，碘视蛋白部分再生，这在室温下其他视觉色素或碘视蛋白的漂白过程中没有观察到。此外，碘视蛋白从漂白的物种缓慢再生。的逆反应被完全抑制取代的溶致NO3-的Cl-，这表明Cl-结合到碘视蛋白干扰光诱导的顺反异构化的生色团。很可能是水分子水合Cl-形成了额外的氢键，通过氢键，释放这种空间位阻所必需的蛋白质构象变化变得不稳定。由于漂白过程的进展是蛋白质构象变化的结果，因此在低温下受到抑制，导致热逆异构化。
The chloride effect on the photobleaching process of iodopsin, a chicken red-sensitive cone visual pigment, was studied in detail by time-resolved low-temperature spectroscopy at -40 degrees C to -10 degrees C. Decay-associated difference spectra obtained by kinetic analysis using the singular value decomposition method were composed of spectra of BL-iodopsin, lumiiodopsin, metaiodopsin I, metaiodopsin II and metaiodopsin III, essentially identical to those at room temperature. In each conversion step however, iodopsin was partially regenerated, which is not observed in the bleaching process for other visual pigments or iodopsin at room temperature. Moreover, iodopsin was slowly regenerated from the bleached species. The reverse reactions were completely suppressed by substitution of lyotropic NO3- for Cl-, suggesting that Cl- binding to iodopsin interferes with light-induced cis-trans isomerization of the chromophore. It is likely that the water molecule hydrating Cl- forms the additional hydrogen bond(s), by which the protein conformational change necessary to release this steric hindrance becomes enthalpic. As progress of the bleaching process is a consequence of protein conformational change, it is suppressed at low temperatures, resulting in thermal back-isomerization.