Elastic Strain Waves in Single Muscle Fibers

肌肉收缩是由构象变化驱动的， 当肌球蛋白分子附着在肌动蛋白上时， 细丝。 这种形状的变化导致了滑动运动之间 这两种肌肉蛋白质，因此，缩短整个 肌肉. 试图理解这个系统的动力学， 依赖于两种方法：（1）使用快速 施加到激活肌肉的机械瞬变和（2）质量 将这些蛋白质作为独立的化学物质 物种 我们的研究重新审视了这两种方法， 理论和实验方法相结合。 从 理论观点，我们将表明，快速机械 应用于单个肌细胞制备物的扰动 导致内部应变波的传播， 可以解释那些被错误地归因于 mysosin动力学。 使用最近的实验方法， 高速激光衍射，我们表明这样波发生，我们 用这些数据来证实我们的理论预测。 我们将 也发展了一种新的理论方法， 相互作用的蛋白质。 在这种新方法中，我们放松了 假设每个肌球蛋白分子独立作用。 相反地， 我们认为每个分子的动力学可以表示为 其行为取决于其动力学的振荡器 邻近肌球蛋白。 这种耦合振荡器系统可以产生 分子系综的动力学， 每个个体的动力学。 这两种方法挑战 经典观点认为肌肉是一个缓慢的、独立的 其动力学可以从实验中提取的分子 使用快速的机械扰动。

Muscle contraction is driven by conformational changes associated with portions of myosin molecules when they are attached to actin filaments. This shape change results in a sliding motion between these two muscle proteins and thus, shortening of the entire muscle. Attempts to understand the dymamics of this system have relied on two approaches: (1) experiments that employ rapid mechanical transients applied to activated muscle and (2) mass action models that treat these proteins as independent chemical species. Our research re-examines these two approaches with a combination of theoretical and experimental approaches. From a theoretical standpoint, we will show that rapid mechanical perturbations applied to single muscle cell preparations lead to propagating waves of internal strain and that these waves may account for the behaviors that have been incorrectly attributed to mysosin kinetics. Using recent experimental methods that employ high - speed laser diffractometry, we show such waves occur and we use such data to corroborate our theoretical predictions. We will also develop a new theoretical approach for modelling thedynamics of interacting proteins. In this new approach, we relax the assumption that each myosin molecule acts independently. Instead, we argue that the kinetics of each molecule can be represented as an oscillator whose behavior depends on the kinetics of its neighboring myosins. This system of coupled oscillators can yield kinetics of an ensemble of molecules that is vastly different from the kinetics of each individual. These two approaches challenge the classic views of muscle as a system of slow, independent molecules whose kinetics can be extracted from experiments employing rapid mechanical perturbations.//