Bukhov N G, Karapetian N V
Biofizika. 1979 Sep-Oct;24(5):806-10.
To elucidate the mechanism of interaction between P700+ and reduced primary electron acceptor in the reaction centres of photosystem I dark relaxation time course of absorption changes at 700 nm was studied at different temperatures. It is shown that in photosystem I subchloroplast fragments with partially inactivated endogenous secondary electron acceptors (treatment by ether or preliminary heating) the recombination of reduced primary acceptor and P700+ is found at -15 degrees C. In fragments with undamaged system of secondary acceptors the recovery of primary photoact in darkness is observed only at temperatures lower than -95 degrees C. At temperatures from -60 degrees to -170 degrees C the electron transfer from reduced primary acceptor to P700+ is described by the first order reaction with half time 250 ms; the rate of this process does not depend on the presence of secondary electron acceptor. The temperature independence of the rate of rapid phase P700+ dark reduction is interpreted as an indication of tunneling mechanisms from reduced primary acceptor to P700+.
为阐明光系统I反应中心中P700 +与还原态初级电子受体之间的相互作用机制，在不同温度下研究了700 nm处吸收变化的暗弛豫时间进程。结果表明，在具有部分失活内源性次级电子受体的光系统I亚叶绿体片段中（用乙醚处理或预加热），在-15℃时发现还原态初级受体与P700 +发生重组。在次级受体系统未受损的片段中，仅在低于-95℃的温度下才观察到暗条件下初级光反应的恢复。在-60℃至-170℃的温度范围内，从还原态初级受体到P700 +的电子转移由一级反应描述，半衰期为250毫秒；该过程的速率不依赖于次级电子受体的存在。P700 +暗还原快速相速率的温度独立性被解释为从还原态初级受体到P700 +存在隧穿机制的一个迹象。
