MECHANOCHEMICAL COUPLING OF CROSS-BRIDGES

这项研究的总体目标是了解分子 肌肉蛋白质将化学能转化为机械能的机制 工作，并获得生理和生理指标之间的精确关联 肌肉收缩的生化事件。将应用新的方法 以横纹肌纤维为研究对象探讨生化关系 收缩蛋白的反应，基本的机械步骤 跨桥周期和相应的结构运动。快速 相关生化物种的化学浓度的变化， 如三磷酸腺苷，将由激光脉冲光解制成的耐光性“笼子” 先驱物。一种新开发的固定光纤末端的方法将是 用于提高图像的一致性和重现性 收缩。由快速长度变化引发的快速机械瞬变 将在改变浓度的条件下获得 生化底物和产品。动力学建模，涉及一部小说 直接从实验确定理论值的方法，将 用来帮助解释结果。等张细丝滑动 收缩蛋白利用的每个底物分子的距离将 确定将酶循环的数量与酶周期的数量相关联 机械性细丝间相互作用。快速重复的步骤 已知和有限浓度的照片发布后的缩写 底物将提供机械力化学的直接指示 耦合比。实验将在单块肌肉上进行 兔腰肌和青蛙半腱肌的纤维 去除表面膜以允许对生化的改变 蛋白质的环境。这个项目的结果应该是 大大提高了对收缩过程的了解，从而带来了 更好地了解纹状体的正常和病理状态 肌肉和其他类型的细胞运动。

The overall aims of this research are to understand the molecular mechanism by which muscle proteins convert chemical energy into mechanical work, and to obtain a precise correlation between the physiological and biochemical events of muscular contraction. Novel methods will be applied to striated muscle fibers to probe the relations between biochemical reactions of the contractile proteins, the elementary mechanical steps of the cross-bridge cycle and the corresponding structural motions. Rapid changes in the chemical concentrations of pertinent biochemical species, such as ATP, will be made by laser pulse photolysis of photolabile "caged" precursors. A newly developed method to secure the fiber ends will be used to improve the uniformity and reproducibility of the contractions.Rapid mechanical transients initiated by quick length changes will be obtained under conditions with altered concentrations of the biochemical substrate and products. Kinetics modelling, involving a novel method to determine theoretical values directly from the experiments, will be used to help interpret the results. The isotonic filament sliding distance per substrate molecule utilized by the contractile proteins will be determined to relate the number of enzymatic cycles to the number of mechanical interfilament interactions. Rapidly repeated steps of shortening after photo release of known and limited concentrations of substrate will provide a direct indication of the mechano-chemical coupling ratio. The experiments will be carried out on single muscle fibers of rabbit psoas and frog semitendinosus muscles that have had the surface membrane removed to allow alterations to the biochemical environment of the proteins. Results from this project should significantly advance knowledge of the contractile process and thus bring a greater understanding of both normal and pathological states of striated muscle and other types of cell motility.