Cosolvent-induced aggregation inhibits myosin ATPase activity by stabilizing the predominant transition intermediate.
Cosolvent-induced aggregation inhibits myosin ATPase activity by stabilizing the predominant transition intermediate.
复制标题
共溶剂诱导的聚集通过稳定主要的过渡中间体来抑制肌球蛋白 ATP 酶活性。
DOI：
10.1021/bi0350093
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发表时间：
2003
期刊：
影响因子：
2.9
通讯作者：
Muhlrad,Andras
中科院分区：
文献类型：
--
作者：
Peyser,YMichael;Shaya,Shirley;Ajtai,Katalin;Burghardt,ThomasP;Muhlrad,Andras
高浓度的共溶剂聚（乙二醇）（PEG）诱导骨骼肌球蛋白亚片段1（S1）的可逆聚集和其Mg-ATP酶活性的抑制[Highsmith等人（1998）Biophys. J.74，1465 - 1472]。在目前的工作中，聚集的ATP酶循环的各个步骤的影响进行了研究。由于模拟水解前M*ATP和水解后M**ADP·Pittransition状态的“捕获”S1·MgADP·phosphate类似物复合物的形成没有受到任何阻碍，因此该循环的异构化和水解步骤不受S1聚集的影响。在MgATP和MgATPγS存在下对Lys-83和Cys-707进行化学修饰也可以得到类似的结论，这表明在溶解和聚集的S1中最常见的循环中间体是M**ADP·Pi。PEG-6000强烈抑制了类似于M**ADP·Pistate的S 1·MgADP·phosphate类似物的解离，表明聚集阻止了从该中间体的转变。这一步骤可能被禁止，因为杠杆臂从关闭位置到打开位置的耦合摆动受到聚集的S1的紧密堆积的约束。
High concentration of the cosolvent poly(ethylene glycol) (PEG) induces reversible aggregation of skeletal myosin subfragment 1 (S1) and inhibition of its Mg-ATPase activity [Highsmith et al. (1998)Biophys. J.74, 1465−1472]. In the present work the effect of aggregation on the various steps of the ATPase cycle was studied. The isomerization and hydrolysis steps of the cycle were not affected by S1 aggregation since the formation of the “trapped” S1·MgADP·phosphate analogue complexes, which mimic the prehydrolysis M*ATP and posthydrolysis M**ADP·Pitransition states, proceeded without any hindrance. Similar conclusions could be reached from the chemical modification of Lys-83 and Cys-707 in the presence of MgATP and MgATPγS, which indicated that the most populated intermediate of the cycle in solubilized and aggregated S1 is M**ADP·Pi. The dissociation of the trapped S1·MgADP·phosphate analogue complexes resembling the M**ADP·Pistate was strongly inhibited by PEG-6000, showing that the transition from this intermediate is prevented by the aggregation. This step is presumably inhibited because the coupled swinging of the lever arm from the closed to the open position is constrained by the close packing of aggregated S1.