Rotation of Single Cross-Bridge in Skeletal Muscle Fiber

骨骼肌纤维中单个横桥的旋转

• 批准号: 7256347
• 负责人: JULIAN BOREJDO
• 金额: $ 14.96万
• 依托单位: UNIVERSITY OF NORTH TEXAS HLTH SCI CTR
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7256347
• 关键词: Active Sites; Anisotropy; Binding; Catalytic Domain; Characteristics; Chemicals; Contracts; Coupled; Development; Dissociation; Event; Fluorescence; Fluorescence Anisotropy; Generations; Individual; Isometric Contraction; Kinetics; Light; Lighting; Measurement; Measures; Mechanics; Methods; Microscope; Monitor; Movement; Muscle; Muscle Contraction; Muscle Fibers; Myosin ATPase; Myosin S-1; Numbers; Phosphate-Binding Proteins; Photobleaching; Photons; Population; Positioning Attribute; Rate; Rotation; Signal Transduction; Site; Skeletal Muscle; Spectrum Analysis; Testing; Time; Work; inorganic phosphate; research study; Active Sites; Anisotropy; Binding; Catalytic Domain; Characteristics; Chemicals; Contracts; Coupled; Development; Dissociation; Event; Fluorescence; Fluorescence Anisotropy; Generations; Individual; Isometric Contraction; Kinetics; Light; Lighting; Measurement; Measures; Mechanics; Methods; Microscope; Monitor; Movement; Muscle; Muscle Contraction; Muscle Fibers; Myosin ATPase; Myosin S-1; Numbers; Phosphate-Binding Proteins; Photobleaching; Photons; Population; Positioning Attribute; Rate; Rotation; Signal Transduction; Site; Skeletal Muscle; Spectrum Analysis; Testing; Time; Work; inorganic phosphate; research study

DESCRIPTION (provided by applicant): The current hypothesis of contraction of skeletal muscle is that the binding of a "fuel" molecule (ATP) to an active site of myosin induces a local conformational change in the catalytic domain --an enzymatically active part of a molecule. This change is mechanically amplified and leads to a major rotation of the regulatory domain -- a long part at the end of myosin that is enzymatically inert. The rotation of the regulatory domain results in the generation of force and movement. The rotation is coupled to the chemical events occurring at the active site of myosin. The aim of this proposal is to test this hypothesis in a single cross-bridge of contracting muscle fiber. A confocal microscope is modified to allow measurements from a small population (approximately 10) of cross-bridges. The rotation of the regulatory domain and the enzymatic activity are measured simultaneously. The rotation is studied by measuring the anisotropy of fluorescence of probes placed at strategic positions within the regulatory domain. The anisotropy is measured either during transient contraction (created by suddenly releasing ATP from a cage) or during steady-state contraction (by using correlation spectroscopy method). The enzymatic activity is measured by fluorescence of phosphate binding protein excited by light emerging from a Near-Field probe. The anisotropy and enzymatic signals are cross-correlated to establish their causal relationship. The significance of this work is that the prevailing hypothesis will be tested, for the first time in a single cross-bridge of working muscle. This is expected to provide definitive answers about the mechanism of contraction of skeletal muscle.

描述（由申请人提供）：骨骼肌收缩的当前假设是，“燃料”分子（ATP）与肌球蛋白活性位点的结合会诱导催化结构域的局部构象变化 - 分子的酶活性部分。这种变化是机械放大的，并导致调节域的重大旋转 - 在肌球蛋白末端的较长部分是酶惰性的。调节域的旋转导致力和运动产生。旋转与在肌球蛋白活性部位发生的化学事件耦合。该提议的目的是在收缩肌肉纤维的单个杂交桥上检验这一假设。对共聚焦显微镜进行了修改，以允许从少量人群（约10）的跨桥进行测量。同时测量调节结构域和酶活性的旋转。通过测量位于调节结构域内战略位置的探针的荧光各向异性来研究旋转。在短暂收缩期间（通过从笼子突然释放出ATP）或在稳态收缩期间（通过使用相关光谱法）测量各向异性。酶活性是通过通过近场探针出现的光激发的磷酸盐结合蛋白荧光来测量的。各向异性和酶促信号交叉相关以建立其因果关系。这项工作的意义在于，将首次在单个工作肌肉的杂交桥上测试了普遍的假设。预计这将提供有关骨骼肌收缩机理的明确答案。