Torsional motion of eosin-labeled F-actin as detected in the time-resolved anisotropy decay of the probe in the sub-millisecond time range.
Torsional motion of eosin-labeled F-actin as detected in the time-resolved anisotropy decay of the probe in the sub-millisecond time range.
复制标题
在亚毫秒时间范围内探针的时间分辨各向异性衰减中检测到伊红标记的 F-肌动蛋白的扭转运动。
DOI：
10.1016/0022-2836(84)90075-5
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发表时间：
1984
影响因子：
5.6
通讯作者：
Akira Ikegami
中科院分区：
文献类型：
--
作者：
Hideyuki Yoshimura;Takuhiro Nishio;Koshin Mihashi;Kazuhiko Kinosita;Akira Ikegami
通过使用激光闪光光解测量伊红标记的 F-肌动蛋白的瞬时吸收各向异性，探索了 F-肌动蛋白在 10−6 至 10−3 秒时间范围内的内部运动。伊红-F-肌动蛋白在 20 °C 时的瞬态吸收各向异性有一个成分在亚微秒时间尺度内衰减至各向异性约为 0.3。然后，该各向异性在约 450 μs 的弛豫时间下衰减到 2 ms 后约 0.1 的残余各向异性。当曙红-F-肌动蛋白的浓度在7至28μm范围内变化时，获得的瞬时吸收各向异性曲线几乎无法区分。这些结果表明各向异性衰减是由曙红-F-肌动蛋白的内部运动引起的。对瞬态吸收各向异性曲线的分析表明，通过各向异性衰减检测到的内部运动主要是F-肌动蛋白螺旋中肌动蛋白原聚体的扭曲；肌动蛋白丝的弯曲仅对测量的衰减产生较小的影响。根据瞬态吸收各向异性计算出的扭转刚度在 20 °C 时为 0.2 × 10−17dyn cm2，这比之前研究确定的弯曲刚度小了大约一个数量级。因此，我们得出结论，F-肌动蛋白在扭曲时比在弯曲时更灵活。经计算，肌动蛋白螺旋中相邻肌动蛋白原聚体之间扭转角的均方根波动在 20°C 时约为 4°。我们还发现，扭转刚度在 5 至 35 °C 的温度范围内大致恒定，并且鬼笔环肽的结合不会明显影响 F-肌动蛋白的扭转运动。
The internal motion of F-actin in the time range from 10−6to 10−3second has been explored by measuring the transient absorption anisotropy of eosin-labeled F-actin using laser flash photolysis. The transient absorption anisotropy of eosin-F-actin at 20 °C has a component that decays in the submicrosecond time scale to an anisotropy of about 0.3. This anisotropy then decays with a relaxation time of about 450 μs to a residual anisotropy of about 0.1 after 2 ms. When the concentration of eosin-F-actin was varied in the range from 7 to 28 μm, the transient absorption anisotropy curves obtained were almost indistinguishable from each other. These results show that the anisotropy decay arises from internal motion of eosin-F-actin. Analysis of the transient absorption anisotropy curves indicates that the internal motion detected by the decay in anisotropy is primarily a twisting of actin protomers in the F-actin helix; bending of the actin filament makes a minor contribution only to the measured decay. The torsional rigidity calculated from the transient absorption anisotropy is 0.2 × 10−17dyn cm2at 20 °C, which is about an order of magnitude smaller than the flexural rigidity determined from previous studies. Thus, we conclude that F-actin is more flexible in twisting than in bending. The calculated root-mean-square fluctuation of the torsional angle between adjacent actin protomers in the actin helix is about 4 ° at 20 °C. We also found that the torsional rigidity is approximately constant in the temperature range from 5 to ~35 °C, and that the binding of phalloidin does not appreciably affect the torsional motion of F-actin.