Abgaryan G A, Christophorov L N, Goushcha A O, Holzwarth A R, Kharkyanen V N, Knox P P, Lukashev E A
Erevan Medical University, Erevan, Armenia.
J Biol Phys. 1998 Mar;24(1):1-17. doi: 10.1023/A:1005039023702.
We describe the phenomenon of light-induced structural transformations in the reaction centers (RC) of photosynthetic bacteria which makes self-regulation of the RC charge separation efficiency possible. The nature of the effect is that the light-driven electron transfer (ET) between the RC redox-cofactors causes structural changes in the protein-cofactors system and this in turn affects the ET kinetics. If the electron-conformation interaction is strong enough, then such self-regulation gives birth to a new RC conformational state of enhanced charge separation efficiency. We show experimental results of stationary and kinetic absorbance change characteristics under different photoexcitation conditions, indicating structural rearrangements on a rather long (minutes) time scale, mainly within the secondary acceptor binding pocket. To simplify the description, in constructing a theory of structure-function reorganization in the RC we employ the adiabatic approach. Final expressions enable us to make qualitative comparison with experimentally observed kinetics of the fast and slow stages of 'free' and 'structurally controlled' electron relaxation, respectively.
我们描述了光合细菌反应中心（RC）中光诱导结构转变的现象，这种现象使得RC电荷分离效率的自我调节成为可能。该效应的本质是，RC氧化还原辅因子之间的光驱动电子转移（ET）导致蛋白质-辅因子系统发生结构变化，进而影响ET动力学。如果电子-构象相互作用足够强，那么这种自我调节会产生一种电荷分离效率增强的新RC构象状态。我们展示了在不同光激发条件下稳态和动力学吸光度变化特征的实验结果，表明在相当长（数分钟）的时间尺度上存在结构重排，主要发生在次级受体结合口袋内。为了简化描述，在构建RC中结构-功能重组理论时，我们采用绝热方法。最终表达式使我们能够分别与实验观察到的“自由”和“结构控制”电子弛豫的快速和慢速阶段的动力学进行定性比较。
