Nicholls P, Butko P
Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada.
J Bioenerg Biomembr. 1993 Apr;25(2):137-43. doi: 10.1007/BF00762855.
Cytochrome c oxidase oxidizes cytochrome c and reduces molecular oxygen to water. When the enzyme is embedded across a membrane, this process generates electrical and pH gradients, and these gradients inhibit enzyme turnover. This respiratory control process is seen both in intact mitochondria and in reconstituted proteoliposomes. Generation of pH gradients and their role in respiratory control are described. Both electron and proton movement seem to be implicated. A topochemical arrangement of redox centers, like that in the photosynthetic reaction center and the cytochrome bc1 complex, ensures charge separation as a result of electron movement. Proton translocation does not require such a topology, although it does require alternating access to the two sides of the membrane by proton-donating and accepting groups. The sites of respiratory control within the enzyme are discussed and a model presented for electron transfer and proton pumping by the oxidase in the light of current knowledge of the transmembranous location of the redox centers involved.
细胞色素c氧化酶氧化细胞色素c并将分子氧还原为水。当该酶嵌入跨膜结构时，这一过程会产生电势梯度和pH梯度，而这些梯度会抑制酶的周转。完整的线粒体和重构的蛋白脂质体中都能观察到这种呼吸控制过程。文中描述了pH梯度的产生及其在呼吸控制中的作用。电子和质子的移动似乎都与之相关。氧化还原中心的拓扑化学排列，类似于光合反应中心和细胞色素bc1复合物中的排列，可确保电子移动导致电荷分离。质子转运不需要这样的拓扑结构，尽管它确实需要供质子基团和受质子基团交替接触膜的两侧。文中讨论了该酶内呼吸控制的位点，并根据目前对所涉及氧化还原中心跨膜位置的了解，提出了氧化酶进行电子传递和质子泵浦的模型。
