Vanadate-induced changes in myosin subfragment-1 from cardiac muscle.
Vanadate-induced changes in myosin subfragment-1 from cardiac muscle.
复制标题
钒酸盐引起心肌肌球蛋白亚片段 1 的变化。
DOI：
10.1006/abbi.1994.1381
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发表时间：
1994
影响因子：
3.9
通讯作者：
Cheung,HC
中科院分区：
文献类型：
--
作者：
Xing,J;Cheung,HC
用稳态荧光法和时间分辨荧光法研究了牛心肌肌球蛋白亚片段1（CS 1）与1，N6-亚乙基腺苷二磷酸（ADP）的相互作用。在pH 7.5和5°C下，结合常数为1.52 × 106 M − 1。在很窄的温度范围内，将与CS 1结合的ADP的强度衰减分解为两个分量。长分量约为22 ns，短分量在5 - 7 ns之间，长分量的分数幅度约为0.6-0.7，短分量的分数幅度约为0.3-0.4。这些数据表明CS 1·ADP复合物的两态温度敏感性转变。在5°C下，在原钒酸盐（Vi）的存在下，长分量的衰减时间几乎不受影响，而短衰减时间增加超过3 ns，并且长分量的分数振幅减小2倍至约0.3，而短分量的分数振幅增加至0.7。无论钒酸盐是否存在，束缚态ADP的各向异性衰减都是单指数的。恢复的单旋转相关时间为110 ns的情况下，钒酸盐和钒酸盐的存在下，79 ns。相关时间的减少表明CS 1·ADP·Vi复合物的分子对称性增加。结果与以前的结果从骨骼S1，并表明，S1从肌球蛋白的两种亚型经历类似的钒酸盐诱导的变化，其流体动力学形状。由于钒酸盐三元络合物是S1·ADP·Pi态的稳定类似物，因此配体诱导的S1流体动力学形状的变化可能与肌球蛋白头部在ATP酶循环中经历的构象变化有关，并且肌球蛋白的这种变化可能是横纹肌中力产生的结构基础。
The interaction between myosin subfragment-1 from bovine cardiac muscle (CS1) and 1,N6-ethenoadenosine diphosphate (ϵADP) was studied using steady-state and time-resolved fluorescence methods. The binding constant was found to be 1.52 × 106M−1at pH 7.5 and 5°C. The intensity decay of ϵADP bound to CS1 was resolved into two components over a narrow range of temperatures. The long component was about 22 ns and the short component was between 5 and 7 ns, with fractional amplitudes of about 0.6-0.7 for the long component and 0.3-0.4 for the short component. These data suggest a two-state temperature-sensitive transition of the CS1·ϵADP complex. In the presence of orthovanadate (Vi) at 5°C, the decay time of the long component was little affected, whereas the short decay time increased by over 3 ns and the fractional amplitude of the long component decreasing by a factor of 2 to about 0.3 and that of the short component increasing to 0.7. The anisotropy decay of bound ϵADP was monoexponential regardless of whether vanadate was present. The recovered single rotational correlation time was 110 ns in the absence of vanadate and 79 ns in the presence of vanadate. The decrease in correlation time suggests an increase in molecular symmetry of the CS1·ϵADP·Vi complex. The results are in agreement with previous results obtained from skeletal S1 and indicate that S1 from both isoforms of myosin experiences similar vanadate-induced changes in its hydrodynamic shape. Since the ternary vanadate complex is a stable analogue of the S1·ADP·Pi state, the ligand-induced change in hydrodynamic shape of S1 may be related to the conformational change which myosin head experiences during the ATPase cycle and this change in myosin could be a structural basis for force generation in striated muscle.