A correlation between proton pumping and the bacteriorhodopsin photocycle.
A correlation between proton pumping and the bacteriorhodopsin photocycle.
复制标题
质子泵浦和细菌视紫红质光循环之间的相关性。
DOI：
10.1073/pnas.81.22.7079
复制
发表时间：
1984
影响因子：
11.1
通讯作者：
T. Ebrey
中科院分区：
文献类型：
--
作者：
Q. Li;R. Govindjee;T. Ebrey
在试图建立质子泵和细菌视紫红质的光循环中间体之间的关系，我们已经研究了pH值和温度对闪光诱导的质子泵和光中间体O 640和M412的影响。闪光引起的质子泵的相对量子产率是pH值和温度依赖。它在酸性pH范围和低温下较高，但在碱性pH范围和高温下降低。M412的衰变是双相的。慢衰减组分（Ms）的振幅与pH有关，其pK与Δ pH相似，快衰减组分（Mf）的pH依赖性与Ms和Δ pH相反，与Ms一样，O_（640）的振幅在酸性pH范围内很高，但与Ms不同，它在pH大于6.5时迅速下降;在pH 8附近，O 640的振幅变为零。Ms的振幅的温度依赖性被发现是类似的Δ pH值，在低温下高，在高温范围内低。Mf和O 640的温度依赖性与Δ pH和Ms的温度依赖性相反。然而，O 640和Ms似乎是质子泵送和光循环之间耦合的可能候选者（从pH依赖性），Ms更可能，因为（i）Ms和Δ pH两者的相对量子产率似乎在较高pH下不变为零，以及（ii）Ms和Δ pH具有类似的温度依赖性。
In an attempt to establish a relationship between proton pumping and the photocycle intermediates of bacteriorhodopsin, we have studied the effects of pH and temperature on flash-induced proton pumping and the photointermediates O640 and M412. The relative quantum yield of flash-induced proton pumping is both pH and temperature dependent. It is high in the acid pH range and at low temperatures but decreases in the basic pH range and at high temperatures. The decay of M412 is biphasic. The amplitude of the slowly decaying component (Ms) was found to be pH dependent with a pK similar to that of the delta pH. The pH dependence of the fast-decaying component (Mf) is opposite to that of Ms and delta pH. Like that of Ms, the amplitude of O640 is high in the acid pH range, but unlike the amplitude of Ms, it declines very rapidly at pHs greater than 6.5; the amplitude of O640 becomes zero around pH 8. The temperature dependence of the amplitude of Ms was found to be similar to that of delta pH, being high at low temperatures and low in the high-temperature range. The temperature dependence of Mf and O640 is opposite to that of delta pH and Ms. Whereas, O640 and Ms seem to be likely candidates (from the pH dependence) for coupling between proton pumping and the photocycle, Ms is more likely because (i) the relative quantum yield of both Ms and delta pH seem not to go to zero at higher pHs and (ii) Ms and delta pH have similar temperature dependence.