铝和铝+钙对小麦幼苗根尖质膜、液泡膜微囊ATP酶和膜流动性的影响

Effects of Al^(3+) and Al^(3+)+Ca^(2+) on ATPases and Membrane Fluidities of Plasma Membrane and Tonoplast Vesicles from Root Tips of Wheat Seedlings

研究了铝和铝 +钙对小麦幼苗根尖质膜、液泡膜微囊H+ ATP酶、Ca2 + ATP酶、Mg2 + ATP酶活性及其动力学参数和膜流动性的影响。在质膜和液泡膜微囊制剂中加入 1.0mmol/L的Al3+(AlCl3)时 ,H+ ATP酶、Ca2 + ATP酶、Mg2 + ATP酶活性和酶促反应的Vmax及膜流动性下降 ,而酶促反应的最适pH和Km 均不受影响。提高酶促反应介质的Ca2 +(CaCl2 )浓度可以缓解Al3 +对膜ATP酶活性和膜流动性的影响。推测Al3

The effects of Al 3+ (AlCl 3) and Al 3+ + Ca 2+ (CaCl 2) in vitro on the activities of H + ATPase, Mg 2+ ATPase, and Ca 2+ ATPase and membrane fluidities of plasma membrane and tonoplast vesicles from root tips of wheat seedlings were investigated. The activities and V max of H + ATPase, Mg 2+ ATPase and Ca 2+ ATPase, and membrane fluidity decreased when Al 3+ 1.0 mmol/L was added to plasma membrane or tonoplast vesicles (Table 2, Figs.1～5). Lesser inhibition by Al 3+ was found on membrane fluidity, the activities and V max of the enzymes from both membrane vesicles when Ca 2+ 2.5 mmol/L was added (Figs.1～5). Al addition in vitro had no effects on K m values for ATP and optimum pH of ATPases (Table 2). These results suggest that the binding of Al to the membrane results in the inhibition of the ATPase activity.