Submillisecond rotational dynamics of spin-labeled myosin heads in myofibrils.
Submillisecond rotational dynamics of spin-labeled myosin heads in myofibrils.
复制标题
肌原纤维中自旋标记的肌球蛋白头的亚毫秒旋转动力学。
DOI：
10.1016/s0006-3495(80)85023-5
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发表时间：
1980
影响因子：
3.4
通讯作者：
Gergely,J
中科院分区：
文献类型：
--
作者：
Thomas,DD;Ishiwata,S;Seidel,JC;Gergely,J
当肌凝蛋白头部与肌动蛋白结合时形成的十字桥旋转运动是大多数肌肉收缩分子模型的基本要素。为了获得这种分子运动的直接信息，我们进行了饱和转移EPR实验，在实验中，自旋标签选择性地和刚性地附着在纯化肌球蛋白和甘油化肌原纤维中的肌球蛋白头部。在没有肌动蛋白的合成肌球蛋白细丝中，光谱显示头部的快速旋转运动，其有效相关时间为10微秒。相比之下，当分离的肌凝蛋白头（亚片段-1）附着在玻璃珠或f -肌动蛋白上时，很少或没有观察到亚毫秒的旋转运动，这表明肌凝蛋白头和肌动蛋白之间的结合在这个时间尺度上是相当刚性的。在旋转标记的肌原纤维中观察到类似的头部固定。因此，我们得出结论，几乎所有的肌凝蛋白头在刚性肌原纤维是固定的，显然是由于头部附着在肌动蛋白。将ATP添加到肌原纤维中，无论是否存在0.1 mM Ca2+，产生的光谱与在没有肌动蛋白的情况下观察到的肌球蛋白丝相似，表明快速的亚毫秒旋转运动。这些结果表明：(a)大多数肌球蛋白头在松弛或激活的肌原纤维中随时分离，或(b)承载ATP水解产物的附着头与分离头一样快速旋转。
The rotational motion of crossbridges, formed when myosin heads bind to actin, is an essential element of most molecular models of muscle contraction. To obtain direct information about this molecular motion, we have performed saturation transfer EPR experiments in which spin labels were selectively and rigidly attached to myosin heads in purified myosin and in glycerinated myofibrils. In synthetic myosin filaments, in the absence of actin, the spectra indicated rapid rotational motion of heads characterized by an effective correlation time of 10 microseconds. By contrast, little or no submillisecond rotational motion was observed when isolated myosin heads (subfragment-1) were attached to glass beads or to F-actin, indicating that the bond between the myosin head and actin is quite rigid on this time scale. A similar immobilization of heads was observed in spin-labeled myofibrils in rigor. Therefore, we conclude that virtually all of the myosin heads in a rigor myofibril are immobilized, apparently owing to attachment of heads to actin. Addition of ATP to myofibrils, either in the presence or absence of 0.1 mM Ca2+, produced spectra similar to those observed for myosin filaments in the absence of actin, indicating rapid submillisecond rotational motion. These results indicate that either (a) most of the myosin heads are detached at any instant in relaxed or activated myofibrils or (b) attached heads bearing the products of ATP hydrolysis rotate as rapidly as detached heads.
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影响因子：
5.6
作者：
HUXLEY, HE;BROWN, W
通讯作者：
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DOI：
10.1073/pnas.75.11.5488
发表时间：
1978
影响因子：
11.1
作者：
D. D. Thomas;C. Hidalgo
通讯作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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自旋标记 F-肌动蛋白在亚毫秒时间范围内的旋转动力学。
影响因子：
5.6
作者：
David D. Thomas;David D. Thomas;John C. Seidel;John C. Seidel;John Gergely;John Gergely
通讯作者：
John Gergely