肌巨蛋白影响肌肉收缩的分子结构基础

The molecular structure basis of muscle contraction

【目的】通过研究与肌肉收缩密切相关蛋白-肌巨蛋白(Titin)的结构特征,探索肌肉收缩的分子结构基础。【方法】采用随机构象搜索和分子动力学模拟退火等分子模拟方法,对Titin蛋白PEVK富含域中的PXXP基序(PVAP、PKKP、PEVP)进行构象搜索和构象分析研究。【结果】构象分析发现,上述PXXP基序的稳定构象集可分为折叠式和伸展式两组,且均以折叠式为优势构象,其中脯氨酸残基为反式构型,满足聚脯氨酸Ⅱ型(PPⅡ)左手螺旋的结构要求,具有可延展性。【结论】PXXP基序的可延展性是Titin蛋白PEVK富含域产生弹性,继而使肌肉产生弹性的分子结构基础。

【Objective】To explore the molecular structure basis of muscle contraction and investigate the structural features of Titin which was closely related to muscle contraction.【Methods】The conformational analysis of the PXXP motifs（PVAP、PKKP、PEVP）in PEVK- rich domain of Titin was carried out by stochastic conformation search and simulated annealing of molecular dynamics.【Results】The conformational analysis showed that there were two main types of the three PXXP motifs： the folded type and the extended one. And the folded conformation was the preferred one. The peptide bond conformation of proline residue in the PXXP motif was transconfigurable and extensible, which matched the left- handed helix structure of polyproline Ⅱ（PP Ⅱ）.【Conclusions】The extensibility of the PXXP motifs contributes to the elasticity of PEVK-rich domain of Titin, which is the molecular structure basis of muscle contraction..