Schutt C E, Lindberg U
Department of Chemistry, Princeton University, NJ 08544, USA.
Acta Physiol Scand. 1998 Aug;163(4):307-23. doi: 10.1046/j.1365-201X.1998.t01-1-00393.x.
Force generation during muscle contraction can be understood in terms of cyclical length changes in segments of actin thin filaments moving through the three-dimensional lattice of myosin thick filaments. Recent anomalies discovered in connection with analysis of myosin step sizes in in vitro motility assays and with skinned fibres can be rationalized by assuming that ATP hydrolysis on actin accompanies these length changes. The paradoxically rapid regeneration of tension in quick release experiments, as well as classical energetic relationships, such as Hill's force-velocity curve, the Fenn effect, and the unexplained enthalpy of shortening, can be given mutually self-consistent explanations with this model. When muscle is viewed as a Markov process, the vectorial process of chemomechanical transduction can be understood in terms of lattice dependent transitions, wherein the phosphate release steps of the myosin and actin ATPases depend only on occurrence of allosteric changes in neighbouring molecules. Tropomyosin has a central role in coordinating the steady progression of these cooperative transitions along actin filaments and in gearing up the system in response to higher imposed loads.
肌肉收缩过程中的力产生可以通过肌动蛋白细肌丝片段在肌球蛋白粗肌丝三维晶格中循环长度变化来理解。最近在体外运动测定中分析肌球蛋白步长以及与皮肤纤维相关时发现的异常现象，可以通过假设肌动蛋白上的ATP水解伴随着这些长度变化来合理化。快速释放实验中张力的异常快速再生，以及经典的能量关系，如希尔力-速度曲线、芬恩效应和无法解释的缩短焓，都可以用这个模型给出相互自洽的解释。当将肌肉视为马尔可夫过程时，化学机械转导的矢量过程可以通过晶格依赖性转变来理解，其中肌球蛋白和肌动蛋白ATP酶的磷酸释放步骤仅取决于相邻分子变构变化的发生。原肌球蛋白在协调这些协同转变沿肌动蛋白丝的稳定进展以及响应更高的外加负荷使系统加速方面起着核心作用。
