van Belzen R, van Gaalen M C, Cuypers P A, Albracht S P
E.C. Slater Institute for Biochemical Research, University of Amsterdam, The Netherlands.
Biochim Biophys Acta. 1990 Jun 1;1017(2):152-9. doi: 10.1016/0005-2728(90)90146-u.
The initial velocity of NADH oxidation by bovine-heart submitochondrial particles was measured at pH 8.0 after pretreatment of these particles with different amounts of the inhibitor piericidine A together with 0.035 mM NADH. The amount of piericidine A required to fully inhibit the NADH oxidation activity extrapolated to exactly 1.0 per Fe-S cluster 2 of NADH:Q oxidoreductase. When no reducing equivalents from NADH were present during the pretreatment, this ratio was 1.2. The difference is explained by assuming that NADH:Q oxidoreductase binds piericidine A more effectively in the reduced state than in the oxidized state. It was also found that after Q10-extraction and reincorporation of submitochondrial particles, the amount of piericidine A required to fully inhibit the NADH oxidation activity of the particles increased with the amount of Q10 present during reincorporation. This is explained by assuming that binding of piericidine A, to the inhibitory site of NADH:Q oxidoreductase requires Q10. When 0.035 mM NADPH instead of NADH was present during the pretreatment of submitochondrial particles with piericidine A, the amount of inhibitor per cluster 2 required to fully inhibit the initial NADH-oxidation activity extrapolated to 0.5. This result strongly suggests that NADH:Q oxidoreductase is a functional dimer.
在用不同量的抑制剂粉蝶霉素A预处理牛心亚线粒体颗粒，并加入0.035 mM烟酰胺腺嘌呤二核苷酸（NADH）后，于pH 8.0条件下测定了NADH氧化的初始速度。完全抑制NADH氧化活性所需的粉蝶霉素A的量，外推至每2个铁硫簇的NADH：泛醌氧化还原酶正好为1.0。当预处理过程中不存在来自NADH的还原当量时，该比例为1.2。这种差异可以通过假设NADH：泛醌氧化还原酶在还原状态下比氧化状态下更有效地结合粉蝶霉素A来解释。还发现，在对亚线粒体颗粒进行辅酶Q10（Q10）提取和重新掺入后，完全抑制颗粒NADH氧化活性所需的粉蝶霉素A的量随重新掺入过程中Q10的量增加而增加。这可以通过假设粉蝶霉素A与NADH：泛醌氧化还原酶的抑制位点结合需要Q10来解释。在用粉蝶霉素A预处理亚线粒体颗粒时，如果存在的是0.035 mM烟酰胺腺嘌呤二核苷酸磷酸（NADPH）而非NADH，则完全抑制初始NADH氧化活性所需的每2个簇的抑制剂的量外推至0.5。该结果强烈表明NADH：泛醌氧化还原酶是一种功能性二聚体。
