Distortions in the photocycle of bacteriorhodopsin at moderate dehydration.
Distortions in the photocycle of bacteriorhodopsin at moderate dehydration.
复制标题
中度脱水时细菌视紫红质光循环的扭曲。
DOI：
10.1016/s0006-3495(91)82225-1
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发表时间：
1991
影响因子：
3.4
通讯作者：
Lanyi,JK
中科院分区：
文献类型：
--
作者：
Váró,G;Lanyi,JK
在适度脱水的胶片（相对湿度在 100% 至 65% 之间）中研究了细菌视紫红质的光反应。光激发后 100 ns 至 100 ms 之间的门控光学多通道分析仪的时间分辨差异光谱被分解为中间体 K、L、M、N 和 O 的差异光谱之和，并将获得的动力学拟合到各种替代方案。数据证实了我们最近针对紫色膜悬浮液提出的具有可逆反应的单一反应序列模型（Váró, G., and J. K. Lanyi. Biochemistry. 1990. 29:2241–2250），但除了 L 与 M 平衡、M 与 N 平衡以及 N 与 O 平衡外，还包括 K 与 L 平衡反应的可逆性。随着脱水程度的增加，动力学越来越受到逆反应的支配。与之前一样，拟合数据需要存在两个串联的 M 物质： L 与 M1 平衡 与 M2 平衡 与 N 平衡。在较低湿度下，M1 与 M2 反应大大减慢。这一步可能是质子单向转移的开关。随着脱水程度的增加，BR 的回收越来越少地通过 N 中间体进行，而越来越多地通过来自两个 M 物种的直接分流进行。正如之前通过类似干燥的细菌视紫红质膜进行的电测量所表明的那样（Váró，G. 和 L. Keszthelyi，1983。Biophys. J. 43：47-51）。后者是不一定与净质子易位相关的途径。
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.