Magyari Klára, Bálint Zoltán, Simon Viorica, Váró György
Department of Physics, University "Babes-Bolyai" Cluj-Napoca, Romania.
J Photochem Photobiol B. 2006 Nov 1;85(2):140-4. doi: 10.1016/j.jphotobiol.2006.05.009. Epub 2006 Aug 10.
The function of three types of bacteriorhodopsins was compared: the wild-type, the bleached and retinal reconstituted and retinal deficient bacteriorhodopsin after retinal addition. The apparent pK(a) of the proton acceptor group for the bleached BR and retinal deficient BR shifted toward higher pH values compared to the wild-type BR. Fitting the photocycle model to the absorption kinetic signals for all three proteins showed the existence of the same intermediates, but the time-dependent concentration of the intermediates was different. Although measurements were made at pH 7, the absorption kinetics and photoelectric signals in both retinal reconstituted samples acted as wild-type bacteriorhodopsin at significantly higher pH. Below pH 3 the retinal deficient and reconstituted sample bleached. These results suggested that the added retinal was not able to rebind in the same position in the protein as in native bacteriorhodopsin. This points out that care should be taken, when bleached bacteriorhodopsin is reconstituted with different retinal analogs.
野生型、漂白后视网膜重构型以及添加视网膜后视网膜缺陷型细菌视紫红质。与野生型细菌视紫红质相比，漂白型细菌视紫红质和视网膜缺陷型细菌视紫红质的质子受体基团的表观pK(a)向更高的pH值移动。将光循环模型拟合到这三种蛋白质的吸收动力学信号上，结果表明存在相同的中间体，但中间体的时间依赖性浓度有所不同。尽管测量是在pH 7下进行的，但在视网膜重构的两个样品中，吸收动力学和光电信号在显著更高的pH值下表现得与野生型细菌视紫红质相同。在pH 3以下，视网膜缺陷型和重构型样品发生了漂白。这些结果表明，添加的视网膜无法像在天然细菌视紫红质中那样在蛋白质的相同位置重新结合。这指出，在用不同的视网膜类似物重构漂白的细菌视紫红质时应谨慎。
