Tanaka H, Ishijima A, Honda M, Saito K, Yanagida T
Department of Biophysical Engineering, Faculty of Engineering Science, Osaka University, Toyonaka, Osaka, Japan.
Biophys J. 1998 Oct;75(4):1886-94. doi: 10.1016/S0006-3495(98)77629-5.
Displacements of single one-headed myosin molecules in a sparse myosin-rod cofilament were measured from bead displacements at various angles relative to an actin filament by dual optical trapping nanometry. The sparse myosin-rod cofilaments, 5-8 micron long, were synthesized by slowly mixing one-headed myosin prepared by papain digestion with myosin rods at molar ratios of 1:400 to 1:1500, so that one to four one-headed myosin molecules were on average scattered along the cofilament. The bead displacement was approximately 10 nm at low loads ( approximately 0.5 pN) and at angles of 5-10 degrees between the actin and myosin filaments (near physiologically correct orientation). The bead displacement decreased with an increase in the angle. The bead displacement at nearly 90 degrees was approximately 0 nm. When the angle was increased to approximately 150 degrees-170 degrees, the bead displacements increased to 5 nm. A native two-headed myosin showed similar size and orientation dependence of bead displacements as a one-headed myosin.
通过双光学捕获纳米技术，从相对于肌动蛋白丝不同角度的珠子位移测量了稀疏肌球蛋白杆状细丝中单个单头肌球蛋白分子的位移。通过将木瓜蛋白酶消化制备的单头肌球蛋白与肌球蛋白杆以1:400至1:1500的摩尔比缓慢混合来合成5-8微米长的稀疏肌球蛋白杆状细丝，使得平均一到四个单头肌球蛋白分子沿细丝分散。在低负载（约0.5 pN）以及肌动蛋白和肌球蛋白丝之间的角度为5-10度（接近生理正确方向）时，珠子位移约为10纳米。珠子位移随角度增加而减小。接近90度时的珠子位移约为0纳米。当角度增加到约150度 - 170度时，珠子位移增加到5纳米。天然双头肌球蛋白显示出与单头肌球蛋白类似的珠子位移大小和方向依赖性。
