KINETIC MECHANISM OF ACTION OF AN UNCOUPLER OF OXIDATIVE-PHOSPHORYLATION
KINETIC MECHANISM OF ACTION OF AN UNCOUPLER OF OXIDATIVE-PHOSPHORYLATION
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DOI：
10.1007/bf01940940
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发表时间：
1977-01-01
影响因子：
2.4
通讯作者：
MCLAUGHLIN, S
中科院分区：
文献类型：
--
作者：
COHEN, FS;EISENBERG, M;MCLAUGHLIN, S
化学渗透假说预测，弱酸解偶联线粒体氧化磷酸化的机制与它们通过人工双层膜运送氢的机制相同。报道了解偶联剂介导的氢在双层膜中传递的动力学研究结果。对取代苯并咪唑5，6-二氯-2-三氟甲基苯并咪唑作用下的黑色脂膜进行了电弛豫测量。最简单的模型与实验数据一致，可以推导出吸附系数和速率常数的值。中性物质的反向扩散是H稳态迁移的限速步骤，中性形式和带电形式的解偶联剂强烈吸附在界面上，膜-溶液界面上的反应发生得足够快，足以维持平衡。对中性和阴离子形式的弱酸的吸附系数以及膜对中性形式的渗透系数的独立测量与动力学研究得出的值吻合较好。
The chemiosmotic hypothesis predicts that the mechanism by which weak acids uncouple oxidative phosphorylation in mitochondria is identical to the mechanism by which they transport H across artificial bilayer membranes. The results of a kinetic study of uncoupler-mediated H transport across bilayer membranes is reported. Electrical relaxation measurements were made on black lipid membranes exposed to the substituted benzimidazole 5,6-dichloro-2-trifluoromethylbenzimidazole. The simplest model consistent with the experimental data allowed values for adsorption coefficients and rate constants to be deduced. The back diffusion of the neutral species is the rate limiting step for the steady state transport of H, the neutral and charged forms of the uncoupler adsorb strongly to the interfaces and the reactions at the membrane-solution interfaces occur sufficiently rapidly for equilibrium to be maintained. Independent measurements of the adsorption coefficients of the neutral and anionic forms of the weak acid and of the membrane permeability to the neutral form agreed well with the values deduced from the kinetic study.