Chetkauskaite A V, Grinius L L
Biokhimiia. 1979 Jun;44(6):1101-9.
NAD+ reduction catalyzed by transhydrogenase (EC 1.6.1.1) from E. coli membrane particles at the expense of NADPH oxidation is coupled with phenyldicarbaundecaborate (PCB-) absorption by the particles. This process is inhibited by oxidative phosphorylation protonophorous uncouplers and by equilibration of concentrations of the substrates and products of the transhydrogenase reaction. Elimination of the water-soluble part of membrane ATPase results in the inhibition of PCB- absorption at the expense of the transhydrogenase reaction energy. Treatment of the particles by dicyclohexyl carbodiimide increases the transhydrogenase-coupled absorption of PCB-. The transhydrogenase-induced increase of pPCB in the suspension of particles is directly correlated with the ratio of ([NADPH].[NAD+])/([NADP+].[NADH]). When this value is equal to 1, no energy-dependent increase of pPCB was observed. NADP+ reduction at the expense of NADH oxidation leads to a decrease in the amount of PCB- absorbed by the particles at the expense of ATP hydrolysis energy. The experimental data suggest that NADPH oxidation in the course of the transhydrogenase reaction is coupled with the formation of a membrane potential with a positive charge localized inside the particles.
大肠杆菌膜颗粒中的转氢酶（EC 1.6.1.1）以NADPH氧化为代价催化NAD⁺还原，此过程与颗粒对苯基二碳硼烷（PCB⁻）的吸收相偶联。该过程受到氧化磷酸化质子载体解偶联剂以及转氢酶反应底物和产物浓度平衡的抑制。去除膜ATP酶的水溶性部分会导致以转氢酶反应能量为代价的PCB⁻吸收受到抑制。用二环己基碳二亚胺处理颗粒会增加转氢酶偶联的PCB⁻吸收。颗粒悬浮液中转氢酶诱导的pPCB增加与（[NADPH]·[NAD⁺]）/（[NADP⁺]·[NADH]）的比值直接相关。当该值等于1时，未观察到pPCB的能量依赖性增加。以NADH氧化为代价的NADP⁺还原会导致以ATP水解能量为代价的颗粒吸收的PCB⁻量减少。实验数据表明，转氢酶反应过程中的NADPH氧化与颗粒内部带正电荷的膜电位形成相偶联。
