SWITCH REACTION IN PHOTOCYCLE OF BACTERIORHODOPSIN

为了加强矢量质子传输， 细菌视紫红质（bR），这是必要的，有一个变化， 分子结构之间的去质子化和再质子化的 发色团-即，至少有两个不同的 功能性光循环中的M-中间体。 我们最近 发表的结果，两个连续的M中间体，M，和 M.，被捕获，其类似于假定的M1和M2状态。 SSNMR 对这两种状态下视网膜发色团的研究表明， 两个去质子化态的化学位移相似 SB 15 N、[12- 13 C]ret、[14- 13 C]ret等。 两种亚异构体，M01和 M，，2，在M，，几乎没有解决通过小分裂在 [ 14- 13 C]相对化学位移 后来的M状态Mn与 到目前为止测试的所有条件下的N状态及其 质子化状态以外的差异尚未在 化学位移。 分辨率比500或750更高 MHz频谱仪（与317 MHz相比）对于解决 近距离中间体的光谱成分， 检查其结构。 进一步的实验将确定 中间体的独特光谱和结构特征 以及它们在bR光循环中的关系。

In order to enforce vectorial proton transport in bacteriorhodopsin (bR), it is necessary that there be a change in molecular structure between deprotonation and reprotonation of the chromophore --- i.e., there must be at least two different M-intermediates in the functional photocycle. We have recently published the results that two consecutive M intermediates, M,, and M., were trapped which resemble the putative M I and M2 states. SSNMR studies on the retinal chromophore in these two states indicate that the two deprotonated states resemble each other in the chemical shifts of SB 15N, [12-13C]ret, [14-13C]ret, etc.. Two subisomers, M01 and M,,2, in M,, were barely resolved through the small splitting in the chemical shift of [ 14-13C]ret. The later M state,Mn, coexists with the N state under all the conditions tested so far and their differences other than protonation state have not yet been detected in terms of chemical shifts. The improved resolution of a 500 or a 750 MHz spectrometer (compared to 317 MHz) is crucial for resolving the spectral components of the close intermediates, a prerequisite for examining their structure. Further experiments will determine the unique spectral and structural characteristics of the intermediates and their relationship in the bR photocycle.