Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, United States of America.
PLoS One. 2011;6(6):e21277. doi: 10.1371/journal.pone.0021277. Epub 2011 Jun 20.
The dynamics of four regions of tropomyosin was assessed using saturation transfer electron paramagnetic resonance in the muscle fiber. In order to fully immobilize the spin probe on the surface of tropomyosin, a bi-functional spin label was attached to i,i+4 positions via cysteine mutagenesis. The dynamics of bi-functionally labeled tropomyosin mutants decreased by three orders of magnitude when reconstituted into "ghost muscle fibers". The rates of motion varied along the length of tropomyosin with the C-terminus position 268/272 being one order of magnitude slower then N-terminal domain or the center of the molecule. Introduction of troponin decreases the dynamics of all four sites in the muscle fiber, but there was no significant effect upon addition of calcium or myosin subfragment-1.
使用饱和转移电子顺磁共振评估了肌纤维中四个原肌球蛋白区域的动力学。为了将自旋探针完全固定在原肌球蛋白的表面，通过半胱氨酸突变将双功能自旋标记物连接到 i,i+4 位置。双功能标记的原肌球蛋白突变体在重组成“幽灵肌纤维”时，其运动的动态降低了三个数量级。运动的速度沿着原肌球蛋白的长度变化，C 末端位置 268/272 的速度比 N 末端结构域或分子的中心慢一个数量级。肌钙蛋白的引入降低了肌纤维中所有四个部位的动力学，但加入钙或肌球蛋白亚基-1后没有显著影响。
