Logunov S L, Knox P P, Zakharova N I, Korvatovsky B N, Paschenko V Z, Kononenko A A
Department of Biology, M.V. Lomonosov State University, Moscow, U.S.S.R.
J Photochem Photobiol B. 1990 Apr 1;5(1):41-7. doi: 10.1016/1011-1344(90)85004-g.
Using picosecond absorption spectroscopy it has been shown that in Rhodobacter sphaeroides reaction centres the substitution of the primary quinone acceptor (QA), ubiquinone-10, by other quinone species (with redox potentials higher or lower than that of ubiquinone-10) has essentially no modifying effect on the reaction centre protein. The molecular relaxation processes that accompany the localization and stabilization of a photo-excited electron on the intermediate acceptor, bacteriopheophytin (I), are not affected, although the subsequent transfer of the electron from I to QA is slowed down. Consequently, this leads to a lower quantum efficiency of high rate of direct I-----QA reaction is normally due to the specificity of the primary quinone species and its binding site in the reaction centre protein which provide optimum steric and chemical conditions for an effective interaction between I and QA.
利用皮秒吸收光谱法已表明，在球形红细菌反应中心，用其他醌类物质（氧化还原电位高于或低于泛醌 - 10的醌类）取代初级醌受体（QA），即泛醌 - 10，对反应中心蛋白质基本上没有修饰作用。伴随光激发电子在中间受体细菌脱镁叶绿素（I）上的定位和稳定化的分子弛豫过程不受影响，尽管随后电子从I转移到QA的过程会减慢。因此，这导致了较低的量子效率，通常高速率的直接I-----QA反应是由于初级醌类物质及其在反应中心蛋白质中的结合位点的特异性，这些为I和QA之间的有效相互作用提供了最佳的空间和化学条件。
