两种状态细菌视紫红质光循环中间产物与pH的关系

本文主要用微机控制的毫秒级闪光动力学光谱仪研究含三体细菌视紫红质(Bacteriorhodopsin,简称BR)的紫膜碎片和含单体BR的DMPC(dimyristoyl-Phosphatidyl-choline)脂质囊泡在不同pH条件下光循环中间产物M_(412)和O_(640)的变化,研究结果表明:BR单体与其三体状态相比,BR单体的光循环中间产物M_(412)的产量受介质pH变化的影响较大,其慢衰减成份的衰减比三体BR慢3—10倍.说明单体BR的结构状态较易受PH影响,单体BR光循环中间产物O_(640)随pH变化的趋势与三体BR的有很大区别,可能是由于不同状态的BR受pH的影响,但其具有不同的构型,导致光循环途径的变化.

THE pH DEPENDENCE OF THE PHOTOCYCLE INTERMEDIATES OF BACTERIORHODOPSIN IN DIFFERENT STATES

The pH dependence of photocycle intermediates M412 and O640 of BR in Purple memdrane fragments with trimers and DMPC vesicle with monomers was studied by using micro-computer controlled flash kinetic spectrophotometer. The results indicate that: (1) the decay of M412 slow-decaying components in BR monomers is about 3-10 times slower than that of in BR trimers. (2) comparing with BR trimers the amount of M412 produced in BR monomers is easier to be effected by pH of medium. (3) the tendency of effect of pH on photocycle intermediate O640 is much different between BR monomers and trimers. Probably it is due to the conformational variation caused by pH effect on BR in different states. The results lead to the variation of photocycle pathway.