MOLECULAR ANGLE TRANSITIONS IN MUSCLE

描述：拟议工作的目的是阐明的作用， 肌球蛋白在肌肉收缩的机制，通过确定旋转 能量转换（ATP水解）过程中横桥的轨迹 和力量的产生。 几种位点特异性光谱探针 将被定位在肌球蛋白跨桥上的空间上分离的位点上。 探针将检测到肽骨架的大规模移动 或与力产生相关的全球跨桥旋转运动， 与能量转换有关的局部跨桥构象变化。 稳态和时间分辨光谱技术遵循 在各种生理状态下的方向敏感探头信号， 在机械扰动以提供全局取向之后， 肌球蛋白动力学 时间分辨技术，偏振荧光 光漂白恢复（PFPR）和时间分辨荧光偏振 （TRFP），在亚毫秒时间内跟踪肌纤维中的探头运动 域 PFPR对探测顺序施加光学瞬态， 平衡而不干扰肌肉纤维系统。 TRFP 响应于机械扰动跟随探针旋转运动 的肌肉纤维。 这些技术，用于不同的生理 状态的纤维，提供独立但互补的信息， 桥梁的秩序和动力。 新的方法来合并数据， 多个探测信号区分本地和全局跨桥 旋转 来自相同探针的不同光谱信号解释了 就探针-蛋白质接触而言，提供了 跨桥 探针-蛋白质的偶极振子模型 接触解释吸收、荧光和圆二色性信号 从复合物分子结构的角度来看。 的 跨桥的局部和全局构造的组合将 制作活动周期中跨桥运动的综合地图 允许局部能量转换事件与全局能量转换事件的相关性， 力生成事件。

DESCRIPTION: The aim of the proposed work is to elucidate the role of myosin in the mechanism of muscle contraction by determining the rotational trajectory of the cross-bridge during energy transduction (ATP hydrolysis) and the generation of force. Several site-specific spectroscopic probes will be localized on spatially separated sites on the myosin cross-bridge. The probes will sense both the large scale movement of the peptide backbone or global cross-bridge rotational movement related to force production and local cross-bridge conformation change related to energy transduction. Steady-state and time-resolved spectroscopic techniques follow the orientation sensitive probe signals in various physiological states and after mechanical perturbations to provide the global orientation and dynamics of myosin. The time-resolved techniques, polarized fluorescence photobleaching recovery (PFPR) and time-resolved fluorescence polarization (TRFP), follow probe movement in muscle fibers on the submillisecond time domain. PFPR imposes an optical transient to probe order that relaxes to equilibrium without any perturbation of the muscle fiber system. TRFP follows probe rotational movement in response to a mechanical perturbation of the muscle fiber. These techniques, used on different physiological states of the fiber, provide independent but complementary information on cross-bridge order and dynamics. New methodology for combining data from multiple probe signals distinguishes local from global cross-bridge rotation. Different spectroscopic signals from the same probes interpreted in terms of probe-protein contacts provide the local conformation of the cross-bridge. A coupled dipole oscillator model of the probe-protein contacts interprets absorption, fluorescence, and circular dichroism signals from the probes in terms of the molecular structure of the complex. The combination of the local and global conformation of the cross-bridge will produce a comprehensive map of cross-bridge movement during the active cycle permitting the correlation of local energy transduction events with global force generating events.