FACTORS AFFECTING MOVEMENT OF F-ACTIN FILAMENTS PROPELLED BY SKELETAL-MUSCLE HEAVY-MEROMYOSIN
FACTORS AFFECTING MOVEMENT OF F-ACTIN FILAMENTS PROPELLED BY SKELETAL-MUSCLE HEAVY-MEROMYOSIN
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DOI：
10.1152/ajpcell.1992.262.3.c714
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发表时间：
1992-03-01
影响因子：
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通讯作者：
SELLERS, JR
中科院分区：
文献类型：
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作者：
HOMSHER, E;WANG, F;SELLERS, JR
机械酶(如肌球蛋白)驱动的荧光标记肌动蛋白细丝运动的测量是研究分子马达的重要方法。假定细丝速度(V(F))类似于肌肉纤维中的无负荷缩短速度(V(U))。描述了可重复地定量这些细丝的移动并选择均匀移动的细丝并指定它们的V(F)的方法。使用这些技术可以将V(F)与V(U)在[ATP]、[ADP]、[P(I)]、pH、离子强度(10-150 mm)和温度(15-30℃)方面的文献值进行比较。V(F)和V(U)在底物和产物浓度以及温度>；20℃的影响方面在数量上相似。然而，V(F)对pH和温度的下降比V(U)更敏感。在离子强度为50-150 mm时，V(F)和V(U)表现出相似的离子强度依赖关系(随离子强度的降低而减小)。在离子强度为50 mm时，V(F)显著减小。使用腺苷5‘-O-(3-硫代三磷酸)的实验结果表明，增加弱结合的交叉桥的数量不会严重影响V(F)。因此，尽管V(F)在某些条件下(离子强度和温度升高>；20度-C)是V(U)的很好的类似物，但在其他条件下不是。必须谨慎地解释动力分析的结果。
The measurement of fluorescent-labeled actin filament movement driven by mechanoenzymes (e.g., myosin) is an important methodology for the study of molecular motors. It is assumed that the filament velocity (V(f)) is analogous to the unloaded shortening velocity (V(u)) seen in muscle fibers. Methods are described to reproducibly quantitate the movement of these filaments and to select uniformly moving filaments and specify their V(f). Use of these techniques allowed comparison of V(f) to literature values for V(u) with regard to [ATP], [ADP], [P(i)], pH, ionic strength (10-150 mM), and temperature (15-30-degrees-C). V(f) and V(u) are quantitatively similar with respect to the effects of substrate and product concentrations and temperatures > 20-degrees-C. However, V(f) is more sensitive to decreases in pH and temperatures < 20-degrees-C than V(u). At ionic strengths of 50-150 mM, V(f) and V(u) exhibit similar ionic strength dependencies (decreasing with ionic strength). At ionic strengths < 50 mM, V(f) is markedly reduced. Results of experiments using adenosine 5'-O-(3-thiotriphosphate) suggest that increasing the number of weakly bound cross bridges does not seriously affect V(f). Thus, although V(f) is a good analogue for V(u) under certain conditions (elevated ionic strength and temperatures > 20-degrees-C), under others it is not. The results of motility assays must be cautiously interpreted.