Palmer T, Jackson J B
School of Biochemistry, University of Birmingham, UK.
FEBS Lett. 1990 Dec 17;277(1-2):45-8. doi: 10.1016/0014-5793(90)80806-t.
At the onset of illumination of chromatophores there was a burst (t1/2 approx. 5 ms) in the rate of the H(+)-transhydrogenase reaction before establishment of the steady-state rate. The burst was suppressed at high pH with a pKa of approx. 8.5. The burst and the steady-state rate were inhibited by either (i) a combination of myxothiazol and carbonylcyanide-p-trifluoromethoxyphenylhydrazone, or (ii) NAD+, or (iii) dicyclohexylcarbodiimide. The results support a model in which substrate binding to H(+)-transhydrogenase is relatively fast. A subsequent slow step is accelerated by the protonmotive force and a third step, possibly product release, is rate-limiting in steady-state turnover during illumination.
在载色体开始光照时，在建立稳态速率之前，H(+)-转氢酶反应速率出现一个爆发（半衰期约5毫秒）。在高pH值（pKa约为8.5）时该爆发受到抑制。该爆发和稳态速率受到以下因素的抑制：(i) 粘噻唑和羰基氰化物-对-三氟甲氧基苯腙的组合，或 (ii) NAD+，或 (iii) 二环己基碳二亚胺。这些结果支持了一个模型，即底物与H(+)-转氢酶的结合相对较快。随后的一个缓慢步骤被质子动力势加速，而第三个步骤，可能是产物释放，在光照期间的稳态周转中是限速步骤。
