鼠脑突触体Mg^(2+)-ATP酶质子泵活性的研究(英文)

THE PROTON PUMPING ACTIVITY OF Mg^(2+)-ATPase OF Rat Brain Synaptosomes

位于突触体质膜的外向型（ｅｃｔｏ） Ｍｇ~２＋－ＡＴＰ酶具有水解 ＡＴＰ活性。能量偶联的 ＡＣＭＡ荧光淬灭实验表示Ｍｇ~2＋－ＡＴＰ酶水解ＡＴＰ时向膜内转移质子，建立跨膜质子梯度，跨膜质子梯度可以被电中性 Ｋ～＋／Ｈ～＋离子载体 Ｎｉｇｅｒｉｃｉｎ消除。利用 Ｈ～＋敏感的 ＢＣＥＣＦ荧光分子测定突触的ｐＨｉ变化，结果表示水解ＡＴＰ产生的质子转移使突触体ｐＨｉ下降了０． １１单位。 ｐ－Ｃｈｌｏｒｏｍｅｒｃｕｒｉｂｅｎｚｏａｔｅ抑制能量依赖的 ＡＣＭＡ荧光淬灭和 ＢＣＥＣＦ探测的ｐＨ下降，提示Ｍｇ～（２＋）－ＡＴＰ酶蛋白结构中的ＳＨ基因可能与质子转移功能有关。

The Mg2+-dependent ATPase on the external surface of isolated rat brain synaptosomes has been studied. The rapidquenching of ACMA fluorescence was detected upon hydrolysis of externally added ATP. which could then be restored up-on addition of nigericin. By using the H+-sensitive probe BCECF, a decrease of 0. 11 unit in intrasynaptosomal PH valuewas measured during hydrolysis of ATP. These results indicate that the Mg^2+-ATPase may function as an inward protonpump. P-ch1oromercuribenzoate was found to have inhibitory effect on the proton translocation function.