肌球蛋白调节轻链去磷酸化调控宰后肌动球蛋白解离机理

肌动球蛋白解离决定宰后肌肉的成熟进程和肉品嫩度，传统理论认为肌钙蛋白、原肌球蛋白和钙蛋白酶调控宰后肌动球蛋白解离，本项目组近期研究发现宰后肌球蛋白调节轻链去磷酸化影响肌动球蛋白解离，但具体调控机理并不明确。该项目拟以宰后肌球蛋白调节轻链去磷酸化水平差异显著肌肉为研究对象，通过肌细胞原位模型和纯化蛋白离体模型实验，确证宰后肌球蛋白调节轻链去磷酸化水平与肌动球蛋白解离的对应关系；用肌球蛋白轻链激酶和抑制剂ML-7体外调节肌球蛋白调节轻链去磷酸化水平，解析去磷酸化前后肌球蛋白重链头部的构象折叠和颈部杠杆位移、转角；采用原位模型和离体模型探明肌球蛋白调节轻链去磷酸化后肌球蛋白与肌动蛋白强结合横桥数量和氢键等作用力变化，分析肌球蛋白调节轻链去磷酸化修饰对肌球蛋白ATP结合域构象的作用，解析肌球蛋白ATPase活性和肌动球蛋白解离能量的变化，揭示宰后肌球蛋白调节轻链去磷酸化调控肌动球蛋白解离机理。

Actomyosin dissociation contributes significantly to muscle aging and meat tenderness. Commonly, it is considered that actomyosin dissocation in muscle during postmortem was regulated by troponin，tropomyosin and calpain. However, we found that actomyosin dissociation was influenced by dephosphorylation of myosin regulatory light chain in postmortem muscle. The relationship of dephosphorylation and actomyosin dissociation will be identified in situ and vitro models based on postmortem muscle with significantly difference in dephosphorylation of myosin regulatory light chain. The myosin regulatory light chain dephosphorylation regulated by myosin light chain kinase and inhibitor ML-7 will be used to study the conformation sheet, neck lever shift and angle of myosin heavy chain. The cross-bridge number and hydrogen bonds in cross-bridge bonding domain will be determined in different dephosphorylation situ and vitro models. The conformation, ATPase activity and actomyosin dissociation energy in ATP binding domain will be investigated. The mechanism of actomyosin dissociation regulated by dephosphorylation of myosin regulatory light chain in postmortem muscle will be brought to lighter.