Engelhard M, Scharf B, Siebert F
Max-Planck-Institut für Molekulare Physiologie, Dortmund, Germany.
FEBS Lett. 1996 Oct 21;395(2-3):195-8. doi: 10.1016/0014-5793(96)01041-1.
The Fourier Transform Infrared (FTIR) spectra of photocycle intermediates of sensory rhodopsin II (pSRII) from Natronobacterium pharaonis were measured. The results of the FTIR experiments indicate considerable conformational movements of pSRII already at the stage of the early K-like intermediate which persist at least during the lifetime of the long lived intermediate. These changes in the amide bond region are more intense than those described for sensory rhodopsin I (SRI) and are quite similar to those observed for rhodopsin. Concomitantly with the deprotonation of the Schiff base a carboxyl group located in a hydrophobic environment is protonated. In analogy to bacteriorhodopsin, this carboxyl group might arise from Asp-75 which probably serves as counter ion to the Schiff base. The protonation reaction differs from the situation observed in SRI where the protonation is pH independent over the range of pH 5-8.
测量了来自嗜盐栖热袍菌的感官视紫红质II（pSRII）光循环中间体的傅里叶变换红外（FTIR）光谱。FTIR实验结果表明，在早期类K中间体阶段，pSRII就已经有相当大的构象变化，这些变化至少在长寿命中间体的存在期间持续存在。酰胺键区域的这些变化比感官视紫红质I（SRI）中描述的变化更强烈，并且与视紫红质中观察到的变化非常相似。与席夫碱的去质子化同时发生的是，位于疏水环境中的一个羧基被质子化。与细菌视紫红质类似，这个羧基可能来自Asp-75，它可能作为席夫碱的抗衡离子。质子化反应与SRI中观察到的情况不同，在SRI中，质子化在pH 5-8范围内与pH无关。
