Structures and Mechanisms of “Heme-oxygenase-like” Non-heme Di-iron Enzymes that Catalyze Complex N-oxygenation and Olefin-installing C–C-Fragmentation Reactions

项目摘要/摘要 使用偶联的二铁簇的酶，这些偶联的二铁簇由羧酸盐和 组氨酸残基在困难的氧化反应中激活氧气起着至关重要的作用 全球碳循环，在DNA生物合成中，在临床上使用的天然合成中- 产品药品。在过去的这一年里，一个新的结构家族双铁酶已经进入 全神贯注。在结构上与血红素加氧酶(HO)有关，这些类HO的二铁氧化酶和 加氧酶(HODOS)已经扩展了已知的双铁催化反应体系 单位，即使新家庭中只有四名成员被分配到生化 功能。在它们的功能中，这些类HO酶产生抗生素( 硝基咪唑)、抗癌药物(链脲佐菌素)和喷气燃料。此外，他们似乎 函数以不同于由 之前在其他系统上的工作。而不是在HO中保持稳定的辅助因素- 蛋白质支架，它们会自发降解，至少在体外，可能是作为 新的工作方式，消除了对合作蛋白质在其 催化循环。这个项目的目标是了解结构和机制。 在所显示的前四个按职能分配的成员中， 生物信息学分析，将成为一个大而多功能的新酶家族。人们的期望是 对其功能原理的理解可能会使新的家庭成为 定向进化新的合成有用的酶活性的特权支架。

Project Summary/Abstract Enzymes that use coupled di-iron clusters that are coordinated by carboxylate and histidine residues to activate dioxygen for difficult oxidation reactions play crucial roles in the global carbon cycle, in DNA biosynthesis, and in synthesis of clinically used natural- product drugs. In this last year, a new structural family of diiron enzymes has come into focus. Related in structure to heme-oxygenase (HO), these HO-like diiron oxidase and oxygenases (HODOs) have already expanded the known catalytic repertoire of the diiron unit, even with only four members of the new family having been assigned biochemical functions. In their functions, these HO-like enzymes produce antibiotics (the nitroimidazoles), cancer drugs (streptozotocin), and jet fuel. Moreover, they appear to function in a manner that is distinct from the functional paradigm that was established by earlier work on other systems. Rather than remaining as stable cofactors within the HO- proteins scaffolds, they spontaneously degrade, at least in vitro, perhaps as part of a novel modus operandi that eliminates the requirement for cooperating proteins in their catalytic cycles. The goal of this project is to understand the structures and mechanisms of the first four functionally assigned members of what appears, on the basis of bioinformatic analysis, to be a large and versatile new enzyme family. The expectation is that an understanding of its functional principles might enable the new family to become a privileged scaffold for directed evolution of new synthetically useful enzyme activities.