Váró G, Lanyi J K
Department of Physiology and Biophysics, University of California, Irvine 92717.
Biophys J. 1991 Feb;59(2):313-22. doi: 10.1016/S0006-3495(91)82225-1.
The photoreaction of bacteriorhodopsin was studied in moderately dehydrated films (relative humidities between 100 and 65%). Time-resolved difference spectra from a gated optical multichannel analyzer, between 100 ns and 100 ms after photoexcitation, were decomposed into sums of difference spectra of the intermediates K, L, M, N, and O, and the kinetics obtained were fitted to various alternative schemes. The data confirm the model of a single reaction sequence with reversible reactions we proposed recently for purple membrane suspensions (Váró, G., and J. K. Lanyi. Biochemistry. 1990. 29:2241-2250) but including reversibility also for the reaction K in equilibrium with L in addition to L in equilibrium with M, M in equilibrium with N, and N in equilibrium with O. With increasing dehydration the kinetics were increasingly dominated by the reverse reactions. As before, fitting the data required the existence of two M species in series: L in equilibrium with M1 in equilibrium with M2 in equilibrium with N. The M1 in equilibrium with M2 reaction was greatly slowed at lower humidities. This step might be the switch for the unidirectional transfer of protons. With increasing dehydration recovery of BR occurred less and less via the N intermediate and increasingly via direct shunts from the two M species. As indicated earlier by electrical measurements with similarly dried bacteriorhodopsin films (Váró, G., and L. Keszthelyi, 1983. Biophys. J. 43:47-51). The latter are pathways not necessarily associated with net proton translocation.
在适度脱水的薄膜（相对湿度在100%至65%之间）中研究了细菌视紫红质的光反应。使用门控光学多通道分析仪在光激发后100纳秒至100毫秒之间获取的时间分辨差光谱被分解为中间体K、L、M、N和O的差光谱之和，并将得到的动力学数据拟合到各种替代方案中。这些数据证实了我们最近为紫色膜悬浮液提出的具有可逆反应的单一反应序列模型（瓦罗，G.，和J.K.兰伊。《生物化学》。1990年。29:2241 - 2250），但除了L与M、M与N、N与O处于平衡外，还包括K与L处于平衡的反应的可逆性。随着脱水程度的增加，动力学越来越受逆向反应主导。和之前一样，拟合数据需要存在两个串联的M物种：L与M1处于平衡，M1与M2处于平衡，M2与N处于平衡。在较低湿度下，M1与M2的平衡反应大大减慢。这一步骤可能是质子单向转移的开关。随着脱水程度的增加，细菌视紫红质通过N中间体的恢复越来越少，越来越多地通过来自两个M物种的直接旁路恢复。正如之前用类似干燥的细菌视紫红质薄膜进行电学测量所表明的那样（瓦罗，G.，和L.凯斯泰利，1983年。《生物物理杂志》。43:47 - 51）。后者是不一定与净质子转运相关的途径。
