Warncke J, Slayman C L
Biochim Biophys Acta. 1980 Jul 8;591(2):224-33. doi: 10.1016/0005-2728(80)90154-1.
The current-voltage characteristics of the ATP-dependent proton pump in the plasma membrane of Neurospora have been explored under varied metabolic conditions imposed by mutation and by differential respiratory inhibition. The reversal potential, or presumed equilibrium potential, for the pump was observed at about -400 mV under energy-replete conditions, and at about -200 mV during a stable metabolic downshift of 55 percent. Steady-state levels of adenine nucleotides and inorganic phosphate, however, were not affected by this partial energy restriction, so that under both normal and restricted conditions the apparent free energy of ATP hydrolysis remained near -500 mV. The results suggest that a normal pump stoichiometry of 1 H+ extruded/1 ATP split is modified to 2 H+/1 ATP, by chronic energy restriction.
在因突变和不同呼吸抑制所施加的各种代谢条件下，已对粗糙脉孢菌质膜中依赖ATP的质子泵的电流-电压特性进行了探究。在能量充足的条件下，观察到该泵的反转电位或假定平衡电位约为-400 mV，而在55%的稳定代谢下调期间约为-200 mV。然而，腺嘌呤核苷酸和无机磷酸盐的稳态水平不受这种部分能量限制的影响，因此在正常和受限条件下，ATP水解的表观自由能均保持在-500 mV附近。结果表明，长期的能量限制会使正常的泵化学计量比（每水解1个ATP泵出1个H⁺）改变为每水解1个ATP泵出2个H⁺ 。
