Structural Origins of Cooperativity in Molten Globule Formation

描述（由申请人提供）：指导当前提案的长期目标是定量了解驱动脱辅基肌红蛋白折叠的基本分子机制。平衡折叠和动力学折叠中间体的详细结构和动力学表征是从氨基酸序列预测蛋白质结构和合理开发药物的关键步骤。这项研究将解决几个重要的问题，周围的平衡脱辅基肌红蛋白折叠途径。最初的研究将集中在表征的拓扑异构性和程度的本地一样的螺旋包装在熔融球结构合奏通过计算建模的网站特定的自旋标签衍生的距离限制。随后的工作将集中在利用弛豫色散NMR测量监测微秒到毫秒的时间尺度动态沿着平衡展开路径，重点解决早期崩溃事件的酸展开状态和合作形成的折叠核前熔融球形成。一旦松弛分散动力学已经彻底探讨了野生型蛋白质，更多的定性测量将对脱辅基肌红蛋白突变体，表现出改变核心包装，以回答基本问题的可塑性和适应性的崩溃过程。

DESCRIPTION (provided by applicant): The long-term objective guiding the current proposal is a quantitative understanding of the fundamental molecular mechanisms driving apomyoglobin folding. Detailed structural and dynamical characterization of equilibrium and kinetic folding intermediates is a critical step toward the prediction of protein structures from amino acid sequence and the rational development of drugs. This research will address several important questions surrounding the equilibrium apomyoglobin folding pathway. Initial studies will focus on characterizing the topological heterogeneity and extent of native-like helical packing in the molten globule structural ensemble through computational modeling of site-specific spin label derived distance constraints. Subsequent work will focus on utilizing relaxation dispersion NMR measurements to monitor microsecond to millisecond timescale dynamics along the equilibrium unfolding pathway with emphasis on resolving early collapse events in the acid-unfolded state and cooperatively formed folding nuclei preceding molten globule formation. Once the relaxation dispersion kinetics have been thoroughly explored in the wild type protein, more qualitative measurements will be made on apomyoglobin mutants which exhibit altered core packing to answer fundamental questions about plasticity and adaptability in the collapse process.