小麦液泡膜H^+-ATPase的Ca^(2+)激活特性

Characterization of Ca^(2+) Stimulation of Wheat Tonoplast H^+-ATPase

纯化小麦液泡膜H+ -ATPase,测定了纯化的小麦液泡膜H+ -ATPase 受Mg2+ 和Ca2+ 双重激活的特性及两种激活状态下酶的特性. Mg2+ 激活时酶水解活性受DCCD的抑制,受磷脂酰丝氨酸(PS)影响明显,ATP水解和泵质子活性相偶联.而在Ca2+ 激活时酶水解活性不受DCCD抑制,受PS影响微弱,Ca2+ 激活时ATP水解与泵质子活性解偶联. Mg2+ 和Ca2+ 对小麦液泡膜H+ -ATPase的激活作用不具有叠加效应.

The stimulations of wheat tonoplast H +\|ATPase by both Mg 2+ and Ca 2+ were measured on the base of purification of the enzyme. The characterizations of the Mg 2+ \|stimulated and Ca 2+ \|stimulated H +\|ATPase were studied. Mg 2+ \|stimulated H +\|ATPase is inhibited by DCCD, and is greatly affected by PS. ATP hydrolysis and the H + pumping of the Mg 2+ \|stimulated H +\|ATPase are coupled. But the Ca 2+ \|stimulated H +\|ATPase is insensitive to DCCD, and is only slightly affected by PS. ATP hydrolysis and the H + pumping of the Ca 2+ \|stimulated H +\|ATPase are uncoupled. The Mg 2+ stimulation and Ca 2+ stimulation of the wheat tonoplast H +\|ATPase have effects on each other.