Kalaidzidis I V, Kaulen A D
Department of Photobiochemistry, A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia.
FEBS Lett. 1997 Dec 1;418(3):239-42. doi: 10.1016/s0014-5793(97)01390-2.
Laser flash-induced photovoltage responses of the D85S and D85T mutants as well as of the wild-type acid blue form are similar and reflect intraprotein charge redistribution caused by retinal isomerization. The Cl- -induced transition of all of these blue forms into purple ones is accompanied by the appearance of electrogenic stages, which is probably associated with Cl- translocation in the cytoplasmic direction. Cl- translocation efficiency of these purple forms is much lower than that of the proton transport by the wild-type bacteriorhodopsin. The values of the efficiency do not exceed 15, 8 and 3% for the D85T, D85S and wild-type acid purple form, respectively. Cl- induces an additional electrogenic phase in the photovoltage responses of the D85S mutant and the wild-type acid purple form. This phase is supposed to be associated with the reversible Cl- movement in the extracellular direction. It is interesting that this component is absent in the photovoltage response of the D85T mutant which has, like halorhodopsin, a threonine residue at position 85.
D85S和D85T突变体以及野生型酸性蓝色形式的激光闪光诱导光电压响应相似，反映了视黄醛异构化引起的蛋白质内电荷重新分布。所有这些蓝色形式向紫色形式的Cl⁻诱导转变伴随着电生阶段的出现，这可能与Cl⁻向细胞质方向的转运有关。这些紫色形式的Cl⁻转运效率远低于野生型细菌视紫红质的质子转运效率。D85T、D85S和野生型酸性紫色形式的效率值分别不超过15%、8%和3%。Cl⁻在D85S突变体和野生型酸性紫色形式的光电压响应中诱导了一个额外的电生阶段。该阶段被认为与Cl⁻在细胞外方向的可逆移动有关。有趣的是，在D85T突变体的光电压响应中不存在该成分，该突变体在85位与嗜盐视紫红质一样具有苏氨酸残基。
