CHEMOMECHANICS OF FAST AND SLOW SKELETAL MUSCLE CELLS

这些实验的重点是机械性能和ATPase活性 为了研究单个横纹肌细胞的调节和 肌动球蛋白三维相互作用的化学力学性质 完好无损的力量生成系统。第一个要检验的假设是 18-20k道尔顿轻链的磷酸化，即所谓的P-Light 链或调节轻链，提供了一种调节机制 肌动球蛋白动力学及其调节缩短速度的机制 当系统被Ca++激活时，ATPase活性。第一套 实验旨在测试我们最近的工作产生的假设 肌球蛋白轻度磷酸化在哺乳动物肌肉中的作用 能量学和力学，其中假定的规则具有明显的 生理作用。第二个假设是底物的变化 (MgATP)或产物(ADP和PI)浓度及其比率变化 测试交叉桥的肌动球蛋白化学和机械动力学 模特们。因此，第二组实验探索了 CrosBridge动力学，旨在生成信息，以允许 收缩的生物化学特性之间的联系 蛋白质和肌肉生理学。详细的动力学机制 发现的磷酸化效应也将通过这些方法进行检验。 兔快肌纤维和慢肌纤维 (比目鱼)将用于确定一般性或特异性 对所获得的结果进行定性和定量的界定 这两种基本骨骼类型之间可能出现的差异 肌肉纤维。

These experiments focus on the mechanical properties and ATPase activities of single striated muscle cells in order to study the regulation and chemomechanical properties of actomyosin interactions in a 3-dimensional intact, force-generating system. The first hypothesis to be tested is that phosphorylation of the 18-20 k dalton light chains, the so-called P-light chains or regulatory light chains, provides a mechanism for modulating actomyosin kinetics and so a mechanism to regulate velocity of shortening and ATPase activity when the system is activated by Ca++. The first set of experiments is designed to test hypotheses generated from our recent work on the role that myosin light phosphorylation plays in mammalian muscle energetics and mechanics wherein the postulated regulation has an apparent physiological role. The second hypothesis is that changes in the substrate (MgATP) or product (ADP and Pi) concentrations and their ratios change actomyosin chemical and mechanical kinetics in ways that test crossbridge models. The second set of experiments thus explores the details of crossbridge kinetics and is designed to generate information that allows a connection to be made between the biochemical properties of contractile proteins and muscle physiology. Detailed kinetic mechanisms for any phosphorylation effects found will also be examined by these methods. Rabbit fast skeletal muscle fibers (psoas) and slow skeletal muscle fibers (soleus) will be used in order to determine the generality or specificity of the results obtained and to define qualitative and quantitative differences that may occur among these two fundamental types of skeletal muscle fibers.