Mechanism of proton-pumping in the cytochrome b/f complex
Mechanism of proton-pumping in the cytochrome b/f complex
复制标题
细胞色素 b/f 复合物中的质子泵浦机制
DOI：
10.1007/bf00029737
复制
发表时间：
2004
影响因子：
3.7
通讯作者：
A. Joliot
中科院分区：
文献类型：
--
作者：
P. Joliot;A. Joliot
已经提出了几种模型来解释与细胞色素 b/f 复合物中电子转移反应相关的质子泵浦机制。能量学考虑表明质子泵与质体醌对细胞色素 b 的氧化耦合。在厌氧条件下的活细胞中进行的实验表明，质子泵浦可以通过两种独立的机制发生。当两种 b 细胞色素在闪光照射之前被还原时，即在长时间黑暗厌氧孵育（> 10 分钟）后，质子泵浦很可能与细胞色素 b 对半醌的还原有关，这种还原发生在靠近膜内表面的位点。生电阶段与质子通过跨膜通道的转移相关。该过程不受 2-n-壬基-4-羟基喹啉 N-氧化物 (NQNO) 的抑制。在重复闪光或有氧条件下，质子泵浦根据改进的 Q 循环机制发生，该机制被 NQNO 抑制。
Several models have been proposed to interpret the mechanism of proton-pumping associated with the electron transfer reactions in the cytochrome b/f complex. Energetics considerations suggest that the proton pump is coupled to the oxidation of cytochrome b by plastoquinone. Experiments performed in living cells under anaerobic conditions suggest that proton-pumping can occur through two independent mechanisms. When the two b cytochromes are reduced prior to a flash illumination i.e. after a long dark anaerobic incubation (>10 minutes), proton-pumping is very likely associated with the reduction of a semiquinone by cyt b which occurs at a site close to the inner face of the membrane. The electrogenic phase is associated with the tranfer of protons via a transmembrane channel. This process is not inhibited by 2-n-nonyl-4-hydroxyquinoline N-oxide (NQNO). Under repetitive-flash or under aerobic conditions, proton-pumping occurs according to a modified Q-cycle mechanism, which is inhibited by NQNO.