钒酸盐对玉米根质膜H^+-ATPase的抑制机理研究

Inhibitory effect of vanadate on plasma membrane H^+-ATPase activity of corn roots

用葡聚糖两相分离法从玉米根中获得高纯度的质膜微囊,在一系列ATP浓度(0~5 000μmol.L-1)下,测定不同钒酸盐浓度(0、30、300μmol.L-1Na3VO4)处理对H+-ATPase酶活性的抑制作用,研究钒酸盐对质膜H+-ATPase的抑制机理。结果表明:在0~3 000μmol.L-1ATP浓度范围下获得的H+-ATPase的动力学参数与0~5 000μmol.L-1ATP浓度范围下有较大差异;钒酸盐对玉米根质膜H+-ATP酶的抑制属非竞争性抑制。此外,玉米根质膜H+-ATPase存在底物(ATP)抑制,在使用DYNAFIT软件对底物抑制机理的相关动力学参数和曲线方程进行了拟合过程中,发现钒酸盐可能掩盖或延缓底物抑制作用。

Plasma membrane of corn roots was isolated by poly-glucose double phases. To investigate the inhibitory mechanism of vanadate on the plasma membrane H^＋-ATPase, the effect of vanadate addition （0, 30, 300μmol· L^-1 Na3VO4） on the plasma membrane H^＋-ATPase activity at the range of 0-5 000μmol· L^-1 ATP was studied. Results showed that kinetic parameter of H^＋-ATPase at 0-5 000μmol· L^-1 ATP differed from that at 0-3 000 μmol· L^-1 ATP. Vanadate was a noncompetitive inhibitor of the plasma membrane H^＋-ATPase. Substrate inhibition of the plasma membrane H^＋ -ATPase happened at high ATP concentration. The kinetic parameter and curve of substrate inhibition were fitted by the DYNAFIT software. The substrate inhibition might be concealed or suspended by vanadate.