Pollard T D, Goldberg I, Schwarz W H
Department of Cell Biology and Anatomy, Johns Hopkins Medical School, Baltimore, Maryland 21205.
J Biol Chem. 1992 Oct 5;267(28):20339-45.
Actin monomers with bound ATP, ADP, or fluorescent analogues of these nucleotides exchange the nucleotide on a second time scale, whereas filaments assembled from each of these species exchange their nucleotide with the solution at least 1,000 times slower than monomers. Filaments assembled from either ATP-actin or ADP-actin are indistinguishable by electron microscopy after negative staining. The dynamic elasticity and viscosity of filaments assembled from ATP-actin or ADP-actin or mixtures of these two species are the same over a wide range of frequencies. These observations do not support a recent suggestion (Janmey, P. A., Hvidt, S., Oster, G. F., Lamb, J., Stossel, T. P., and Hartwig, J. H. (1990) Nature 347, 95-99) that ATP hydrolysis within actin filaments stiffens the polymer and alters both their structure and affinity for nucleotides. The difference in observations between these two studies may be related to time-dependent changes in ADP-actin prepared in slightly different ways.
结合有ATP、ADP或这些核苷酸荧光类似物的肌动蛋白单体在第二个时间尺度上会再次交换核苷酸，而由这些种类中的每一种组装而成的细丝与溶液交换其核苷酸的速度比单体至少慢1000倍。经负染后，通过电子显微镜观察，由ATP - 肌动蛋白或ADP - 肌动蛋白组装而成的细丝无法区分。由ATP - 肌动蛋白或ADP - 肌动蛋白或这两种物质的混合物组装而成的细丝在很宽的频率范围内，其动态弹性和粘度是相同的。这些观察结果并不支持最近的一种观点（扬米，P.A.，赫维特，S.，奥斯特，G.F.，兰姆，J.，斯托塞尔，T.P.，和哈特维希，J.H.（1990年）《自然》347卷，95 - 99页），即肌动蛋白细丝内的ATP水解会使聚合物变硬，并改变其结构和对核苷酸的亲和力。这两项研究观察结果的差异可能与以略有不同方式制备的ADP - 肌动蛋白中随时间变化的情况有关。
