REGULATORY INTERACTIONS IN PROTEIN/NUCLEIC ACID SYSTEMS

这项研究计划的长期目标是了解 多亚单位蛋白质等的调控机制 大分子组装。我们感兴趣的是澄清 单个分子组成发挥作用的物理基础 作为生产和控制生物功能的系统， 方法是研究蛋白质-蛋白质相互作用的过程和 特定体系中的蛋白质-配体相互作用通过(A) 描述中的组件和交互 热力学和动力学术语和(B)与这些性质相关 相互作用分子的特定分子结构，以及 它们已知的生物学功能。计划的组成部分 包括：(A)开发新的研究方法 相互作用系统和(B)关于 大分子中键合过程的热力学 装配。 通过这笔赠款资助的工作，我们最近实现了 发展研究方法的重大突破 八种血红蛋白四聚体的功能能量学 血红素位点结扎的中间状态。这打开了 获取以前无法获取的关于以下方面的知识的大门 中间态物种的性质及其在生物化学中的作用 合作机制。初步研究表明，每一种 四聚体分子充当三能级分子开关 控制配基亲和力；10个连接的特定分布 三个合作级别之间的状态物种定义了一种“代码” 用于分子开关机制。通过扩展这些 研究涵盖了更广泛的条件(pH， 温度、DPG、C1和其他血红素位点配体)我们将 确定影响的一般程度，以及影响的分布 自由能态(以及它们的热焓和熵 组件)由生理调节控制 物种。我们计划将这些研究与使用 突变改变的氨基酸残基作为热力学 记者团体绘制合作自由能的路径 在血红蛋白四聚体中的转导。 这项研究计划现在正处于最令人兴奋的阶段：我们 即将能够真正推导出 血红蛋白控制系统中的分子开关。这将是 构成了史无前例的进步，对 调控蛋白质组装体领域。

The long range goal of this research program is to understand mechanisms of regulation in multisubunit proteins and other macromolecular assemblies. We are interested in elucidating the physical bases whereby individual molecular components operate in concert as systems to produce and control biological functions, approach is to study processes of protein-protein interactions and protein-ligands interactions in specific systems by (a) characterizing the components and the interactions in thermodynamic and kinetic terms and (b) relating these properties to specific molecular structures of the interacting molecules, and to their known biological functions. Components of the program include: (a) development of new methods for the study of interacting systems and (b) theoretical work on the thermodynamics of linked processes in macromolecular assemblies. Through work funded by this grant we recently achieved a significant breakthrough by developing methods to study the functional energetics of hemoglobin tetramers in all eight intermediate states of heme-site ligation. this has opened the door to obtaining previously-inaccessible knowledge regarding properties of the intermediate state species and their roles in the cooperative mechanism. Initial studies indicate that each tetrameric molecules acts as a three-level molecular switch to control ligand affinity; a specific distribution of the ten ligation state species among the three cooperative levels defines a "code" for the molecular switching mechanism. By extending these studies to encompass a wider range of conditions (pH, temperature, DPG, C1, and other heme-site ligands) we will determine how general the effects are, and how the distribution of free energy states (and their enthalpic and entropic components) are controlled by the physiological regulatory species. We plan to combine these studies with the use of mutational altered amino acid residues as thermodynamic reporter groups to map the pathways of cooperative free energy transduction within the hemoglobin tetramers. This research program is now at its most exciting stage: we are on the verge of being able to actually deduce the rules of molecular switching in the hemoglobin control system. This will constitute an unprecedented advance of singular importance to the field of regulatory protein assemblies.