首页> 外文期刊>The biochemical journal >Pressure-relaxation studies of pyrene-labelled actin and myosin subfragment 1 from rabbit skeletal muscle. Evidence for two states of acto-subfragment 1
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Pressure-relaxation studies of pyrene-labelled actin and myosin subfragment 1 from rabbit skeletal muscle. Evidence for two states of acto-subfragment 1

机译:从兔骨骼肌中芘标记的肌蛋白和肌蛋白次蛋白1的压力放松研究。两个缔约国的证据1

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pWe have used actin labelled at Cys-374 with N-(1-pyrenyl)iodoacetamide [Kouyama & Mihashi (1981) Eur. J. Biochem. 114, 33-38] to monitor pressure-induced relaxations of acto-myosin subfragment 1. This label greatly increases the sensitivity of measurement of dissociated actin and reveals the presence of two relaxations. The experimental data can be fitted by a model in which actin binds subfragment 1 relatively weakly (K = 5.9 × 10(4) M-1) and then isomerizes to a more tightly bound complex (K = 1.7 × 10(7) M-1). This directly observed isomerization supports the model of Geeves, Goody & Gutfreund [(1984) J. Muscle Res. Cell. Motil. 5, 351-361]. The rate of the isomerization is too high to be observed in the pressure-jump apparatus (less than 200 microseconds), but analysis of the amplitudes allows estimation of the equilibrium constant of the isomerization as 280 (20 degrees C, 0.1 M-KCl, pH 7). The equilibrium is sensitive to temperature, pressure, ionic strength and the presence of ethylene glycol. The pressure-sensitivity of the isomerization suggests a significant conformational change of the acto-myosin subfragment 1 complex./p
机译:我们已经使用Cys-374标记的肌动蛋白,N-(1-芘基)碘乙胺[Kouyama& Mihashi(1981)欧元。 J. Biochem。 114,33-38]监测肌动菌菌丝素次帧的压力诱导的弛豫。该标签大大增加了解离肌动蛋白的测量的灵敏度,并揭示了两种放松的存在。实验数据可以由肌动蛋白相对弱(k = 5.9×10(4)m-1)结合的模型装配,然后异构化为更紧密的复合物(k = 1.7×10(7)m- 1)。这是直接观察到的异构化支持Geeves,Goody&amp的模型; Gutfreund [(1984)J. Muscle Res。细胞。 motil。 5,351-361]。在压力 - 跳转装置(小于200微秒)中观察到异构化的速率太高,但振幅的分析允许估计异构化的平衡常数为280(20摄氏度,0.1 m-Kcl, pH7)。平衡对温度,压力,离子强度和乙二醇的存在敏感。异构化的压力敏感性表明,肌动菌菌丝素次次次次复合物的显着构象变化。

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