ORGANOMETALLIC MODELS FOR B12 CATALYZED REACTIONS

B12 催化反应的有机金属模型

• 批准号: 3292535
• 负责人: JOHN W SUGGS
• 金额: $ 5.86万
• 依托单位: BROWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1986
• 资助国家: 美国
• 起止时间: 1986-07-01 至 1989-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3292535
• 关键词: 1 carbon compound; allosteric site; catalyst; chelating agents; chemical binding; chemical reaction; ligands; organometallic compounds; phenanthrolines; vitamin B12 coenzyme

Reactions mediated by the coenzyme B12 are not only important for the maintenance of human health, they are some of the most unusual chemical transformations known. Previous work has suggested that B12 catalyzed reactions are initiated by homolysis of a cobalt-carbon bond. However, in the absence of protein and substrate the cobalt-carbon bond in B12 is reasonably stable. Our goal is to prepare systems which mimic this substrate-induced homolysis of a metal-carbon bond. The effect of the substrate in B12 systems is one example of an allosteric effect, so that our proposed work should shed light on the general problem of the mechanisms, at the molecular level, of allosteric effects. The particular system on which attention will be focused will be orthometalled derivatives of 2-phenyl-1,10-phenanthroline. Transition metals react with this ligand (and its derivatives) to form tridentate N,N,C chelates. In these complexes the phenyl ring is kept in the plane of the 1,10-phenanthroline ring by the metal carbon bond. Metal-binding groups will be placed on the ortho position of the metallated phenyl ring so that upon addition of a metal ion (such as Mg++) a torque will be induced, breaking the metal-carbon bond. Thus, this system will model how substrate binding can promote M-C homolysis. The chemistry of these M-C diradicals will be studied to see if they can carry out the same rearrangements as B12 based enzymes.

由辅酶B12介导的反应不仅对 维护人类健康，它们是最不寻常的化学物质 已知的转换。 以前的工作表明B12催化 反应是通过钴 - 碳键的同同源性引发的。 但是，在 缺乏蛋白质和底物B12中的钴 - 碳键为 合理稳定。 我们的目标是准备模拟这一点的系统 底物诱导的金属碳键同伊。 效果 B12系统中的底物是变构效应的一个例子，以便 我们提出的工作应该阐明 分子水平的机制具有变构作用。 关注关注的特定系统将是 2-苯基-1,10-苯磺烷的矫正衍生物。 过渡 金属与该配体（及其衍生物）反应形成三叉戟 N，N，C螯合物。 在这些配合物中，苯环保持在 金属碳键的1,10-苯磺氨酸环。 金属结合 组将放置在金属苯环的矫正位置 因此，在添加金属离子（例如mg ++）后，扭矩将是 诱导，打破金属碳键。 因此，该系统将建模 底物结合可以促进M-C同型。 这些M-C的化学 将研究Diradicals，以查看是否可以执行相同的 重排为基于B12的酶。