Hirayama J, Imamoto Y, Shichida Y, Yoshizawa T, Asato A E, Liu R S, Kamo N
Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
Photochem Photobiol. 1994 Oct;60(4):388-93. doi: 10.1111/j.1751-1097.1994.tb05121.x.
To investigate the shape of the chromophore binding site of pharaonis phoborhodopsin (ppR), ppR-opsin was incubated with five ring-modified retinal analogs: an acyclic retinal, phenylretinal, alpha-retinal, cyclohexylretinal and 5-isopropyl-alpha-retinal. The experimental results were compared with those obtained from bacteriorhodopsin-opsin (bR-opsin) and the same retinal analogs. It was suggested that ring chain conformation is important in affecting the spectral shoulder unique for the absorption spectrum of ppR. The rate of pigment formation depended greatly on the analogs used with the planar analogs showing rapid formation. Thus, we concluded that the space of the retinal binding site of ppR is restricted to the plane of the cyclohexenyl ring of the chromophore, whereas that of bR is less restricted.
为了研究法老嗜盐菌视紫红质（ppR）发色团结合位点的形状，将ppR视蛋白与五种环修饰的视黄醛类似物一起孵育：无环视黄醛、苯基视黄醛、α-视黄醛、环己基视黄醛和5-异丙基-α-视黄醛。将实验结果与用嗜盐菌视紫红质视蛋白（bR-视蛋白）和相同视黄醛类似物得到的结果进行比较。结果表明，环链构象对于影响ppR吸收光谱特有的光谱肩很重要。色素形成的速率很大程度上取决于所使用的类似物，平面类似物显示出快速形成。因此，我们得出结论，ppR视黄醛结合位点的空间局限于发色团环己烯基环的平面，而bR的空间限制较小。
