Kinetics and Mechanism of Iron-Ligand Exchange Reactions in the Presence of Surfactants and/or Crown Ethers

这个项目的主要目标是阐明微生物中的机制，即铁在适当的时间和位置从其极其稳定的载体中释放出来。将进行使用胶束的模型实验，这些胶束旨在探索水/电池界面对铁载体和其他多齿螯合剂中铁的稳定的可能影响。将测试水/胶束界面对铁/配体交换动力学的影响，例如，亲水铁载体铁氧胺B和胶束结合的疏水螯合剂苯异羟肟酸之间的交换动力学。在一些实验中，邻菲罗啉也会被引入到胶束中，因为初步数据表明，菲咯啉通过氧化还原机制加速了铁/配体交换进入胶束假相。为了评价二次配位壳层对铁(III)-配体解离动力学的影响，我们将研究水溶液中的超分子组装。疏水冠醚可以使这些超分子组装在胶束“表面”上形成。这些组装体可以作为细胞表面受体复合体的模型。将测量这些超分子组件(例如，铁胺B冠醚-表面活性剂)中配体交换的动力学，以及三元络合物的形成对这些动力学的影响。%在化学系无机、生物无机和有机金属项目中，杜克大学的Alvin L.Crumbliss博士将在适当的时间和地点模拟铁在微生物中释放的方式。细菌含有能有效结合和运输铁的分子，其中一些被用作螯合疗法的药物。这些生物无机实验的结果将加深我们对微生物铁的运输机制和与金属提取过程相关的机制的理解。

The principal goal in this project is to elucidate the mechanism in microbes whereby iron is released from its extremely stable carrier at the appropriate time and location. Model experiments which use micelles designed to probe possible effects of the aqueous/cell interface on the labilization of iron from siderophores and other polydentate chelators will be performed. The influence of the aqueous/micelle interface on the kinetics of iron/ligand exchange between, for example, the hydrophilic siderophore ferrioxamine B and a micelle bound hydrophobic chelator, benzohydroxamic acid, will be tested. Phenanthroline will also be incorporated into the micelle in some experiments, as preliminary data show that phenanthroline accelerates iron/ligand exchange into the micellar pseudo-phase via a redox mechanism. Supramolecular assemblies in aqueous solution will be investigated in order to evaluate second coordination shell effects on iron(III)-ligand dissociation kinetics. Hydrophobic crown ethers may permit these supra- molecular assemblies to form on micelle "surfaces". These assemblies may be used as models for cell surface receptor complexes. The kinetics of ligand exchange within these supra- molecular assemblies (e.g., ferrioxamine B-crown ether- surfactant) and the influence that ternary complex formation has on these kinetics will be measured. %%% In this project in the Inorganic, Bioinorganic, and Organo- metallic Program of the Chemistry Division, Dr. Alvin L. Crumbliss of Duke University will model the way in which iron is released in microbes at the appropriate time and location. Bacteria contain molecules which bind and transport iron so efficiently that some are used as drugs in chelation therapy. The results of these bioinorganic experiments will enhance our understanding of microbial iron transport mechanisms and mechanisms related to metal extraction processes.