REGULATORY INTERACTIONS IN PROTEIN/NUCLEIC ACID SYSTEMS

这项研究计划的长期目标是了解 多亚基蛋白质和其他 大分子组装体 我们有兴趣阐明 单个分子成分起作用的物理基础 作为产生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， 在特定系统中的蛋白质-配体相互作用（a） 表征组件和相互作用， 热力学和动力学项，以及（B）与这些性质相关的 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。 方案的组成部分 包括：（a）发展新的研究方法， 相互作用系统和（B）理论工作的 大分子链过程热力学 组件. 通过这项赠款资助的工作，我们最近取得了 通过开发方法来研究 血红蛋白四聚体的功能能量学 血红素位点连接的中间状态。 这开启了 获得以前无法获得的关于 中间态物种的性质及其在 合作机制 初步研究表明， 四聚体分子充当三级分子开关， 控制配体亲和力;十个连接的特定分布 三个合作级别之间的状态物种定义了一个“代码” 分子转换机制的关键。 通过扩展这些 研究包括更广泛的条件（pH， 温度，DPG，C1和其他血红素位点配体），我们将 确定影响的普遍程度以及分布 自由能态（以及它们的能量和熵 成分）由生理调节控制 物种 我们计划将联合收割机与 突变改变的氨基酸残基作为热力学 报告小组绘制合作自由能的途径 在血红蛋白四聚体内的转导。 这项研究计划现在正处于最令人兴奋的阶段： 即将能够推导出 血红蛋白控制系统中的分子转换。 这将 这是一个前所未有的进步， 调节蛋白质组装的领域。

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.