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本文用马来酰亚胺系列(MSL)及溴乙酰胺自旋标记物为探针,分别研究了透析液中1mmol/L浓度的Mg~(2+)对重建脂酶体上猪心线粒体H~+-ATP酶构象的影响。发现Mg~(2+)可以显著提高经标记后重建的H~+-ATP酶——L·(F_0·F_1)的ESR图谱中的强弱固定化比值(S/W)。用胰蛋白酶加尿素切下经MSL标记的L·(F_0·F_1)中的F_1部分,剩留的L·(F_0)部分的S/W值仍是有Mg~(2+)的比无Mg~(2+)的高。单独提纯的F_1经MSL标记后在无Mg~(2+)、有Mg~(2+)透析20h,二者ESR图谱无明显差异。上述结果支持我们前曾提出的模型,即Mg~(2+)通过与磷脂相互作用,改变其物理状态,引起H~+-ATP酶复合体中F_0部分的构象首先发生变化,然后这一变化再传递至复合体中活性中心所在的F_1部分。
In this paper, the probe of maleimide series (MSL) and bromoacetamide spin labels were used to investigate the effect of 1 mmol / L Mg 2+ on the reconstitution of porcine mitochondrial H ~ + -ATP enzyme conformation. It was found that Mg ~ (2+) could significantly increase the S / W ratio of ESR patterns of labeled H ~ + -ATPase-L · (F_0 · F_1). The F_1 fraction of L · (F_0 · F_1) labeled with MSL was excised by adding trypsin and urea. The S / W value of the remaining L · (F_0) fraction was still higher than that of Mg 2+ ~ (2+) high. There was no difference in the ESR patterns of F_1 isolated by MSL without Mg 2+ and Mg 2+ dialysis for 20h. The above results support our previous model that Mg 2+ changes its physical state through interaction with phospholipids, causing the conformation of the F_0 moiety in the H + -ATPase complex to change first, and then this change And then passed to the F_1 part of the complex where the active center is located.