摘要
本文利用动力学方法研究了乙醇对F_1-ATP酶和H^(+)-ATP酶复合体的抑制与其结合核苷酸位点状态的关系,结果表明天然情况下乙醇对F_1呈现反竞争性抑制类型,对H^(+)-ATP酶呈现非竞争性抑制类型,且乙醇对F_1和H^(+)-ATP酶的抑制与核苷酸结合位点的构象密切相关。游离状态下和膜结合状态下的F_1在部分结合的核苷酸被洗脱前后动力学行为的不同,反映了二种状态下的F_1具有不同的构象,且F_0和膜脂对F_1起着一定的调控作用。
A kinetic study was carried out to investigate the relationship between the ethanol inhibition and the state of nucleotide binding site of F1-ATPase and H+-ATPase complex. The experimental results show that under natural condition ethanol appeared to be an uncompetitive inhibitor toward F1-ATPase and non-competitive inhibitor toward H+-ATPase complex. When part of the nucleotides were washed out from F, or H+-ATPase complex, the Km of F1-ATPase changes from 0.2mmol/L to 0.5mmol/L. The type of inhibition of F1-ATPase or H+-ATPase complex inhibited by ethanol did not change after nucleotides removal. The K4 of F1-ATPase changes from 0.7mol/L to 4.0mol/L, and the degree of inhibtion by ethanol increases. In the case of H+-ATPase complex in the presence of inhibitor after the nucleotides removal, Km changes from 0.3mmol/L to 0.6mmol/L, K1 changes from 4.0mol/L to 2.2 mol/L and the degree of inhibition decreases. These results indicate that the ethanol inhibition of F1-ATPase and H+-ATPase complex is closely related to the conformation of the nucleotides binding site of the enzymes. On the other hand, the difference of kinetic behavior of F1 in free state and membranebound state before and after nucleotides removal reflects the existence of the conformational difference of F1 in the two states. It seems that the F0 and membrane lipids exert regulatory effect to F1 which is in the membrane-bound state.
基金
国家自然科学基金
关键词
F1-ATP酶
H-ATP酶
乙醇
抑制
Mitochondria, F1-ATPase, H+-ATPase complex, Ethanol inhibition, Nucleotide binding site
