Structural Energetics of Hemoglobin Intermediates

描述(申请人提供)：这项研究的目标是确定调节人与人之间交流的分子机制和驱动力 人血红蛋白的氧结合部位。总的氧结合 然而，血红蛋白的性质是有据可查的，然而， 积极的协作性，这是生理效果的关键，但不是 明白了。血红蛋白四聚体中的主要功能单位有 直到最近才被确定为其Alphabeta二聚体组件，如 结构能量学在中间态之间的分布。这份订单 氧结合以及它的释放遵循特定的组合 规则，优先与四聚体内一个二聚体上的两个位点结合， 然后与剩余二聚体上的位点结合。这种功能不对称 在血红蛋白四聚体中也观察到了杂交的初步研究 四聚体，其中一个Alphabeta二聚体是正常的，但另一个二聚体包含一个 交叉二聚体界面上的单一氨基酸。修改后的效果 关于氧结合的协同自由能只有在改性后才能感受到 二聚体，而正常二聚体不受明显影响。艾克斯博士的计划 将这些研究扩展到使用重组血红蛋白的02中间体 设计了几组改变后的残留物。亚基间的相互作用 重组系统将通过动力学、分析凝胶等技术进行研究 层析，低温等电聚焦，以及直接02 有约束力的。由于HB监管制度是一个重要的原型， 协作性多部位调节组件家族，开发的方法 该方案应具有广泛的适用性。对人类更深入的理解 HB机制也是当前对潜在的红细胞设计感兴趣的 替代氧气载体和以血红蛋白为基础的药物输送系统。

DESCRIPTION (provided by applicant): The goal of this research is to determine the molecular mechanism and driving forces that regulate communication between the oxygen binding sites of human hemoglobin. The overall oxygen binding properties of hemoglobin are well-documented, however, the molecular basis of positive cooperativity, which is crucial to physiological efficacy, is not understood. The primary functional units within the hemoglobin tetramer have only recently been identified as its alphabeta dimer components, as shown by the distribution of structural energetics among intermediate states. The order of oxygen binding, as well as its release, follows specific combinatorial rules, binding preferentially to both sites on one dimer within the tetramer, then binding to the sites on the remaining dimer. This functional asymmetry within the hemoglobin tetramer is also observed in initial studies on hybrid tetramers, where one alphabeta dimer is normal but the other dimer contains a single amino acid in the cross-dimer interface. The effect of the modification on the cooperative free energy of oxygen binding is felt only on the modified dimer, while the normal dimer is not significantly affected. Dr. Ackers plans to extend these studies for the 02 intermediates using recombinant hemoglobins with designed sets of altered residue sites. Subunit interactions of the recombinant systems will be studied by techniques of kinetics, analytical gel chromatography, cryogenic isoelectric focusing, as well as by direct 02 binding. As the Hb regulatory system is an important prototype for a large family of cooperative multi-site regulatory assemblies, the methods developed by this program should have wide applicability. Deeper understanding of human Hb mechanisms is also of current interest to the potential design of red cell substitute oxygen carriers and hemoglobin-based drug delivery systems.