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

项目概要/摘要 使用偶联的二铁簇的酶，所述偶联的二铁簇由羧酸根和 组氨酸残基活化分子氧进行困难的氧化反应， 全球碳循环，DNA生物合成，以及临床使用的天然- 毒品产品。在过去的一年里，一个新的结构家族的二铁酶已经进入 专心点在结构上与血红素加氧酶（HO）相关，这些HO样二铁氧化酶和 加氧酶（霍多斯）已经扩展了已知的二铁催化库， 单位，即使只有四个成员的新家庭已被分配生化 功能协调发展的在它们的功能中，这些HO样酶产生抗生素（ 硝基咪唑），抗癌药物（链脲霉素）和喷气燃料。此外，他们似乎 以一种不同于由以下方式建立的功能范式的方式发挥作用： 在其他系统上的早期工作。而不是作为HO内的稳定辅因子保持不变， 蛋白质支架，它们自发降解，至少在体外，也许作为一个 新的工作方式，消除了合作蛋白质的要求， 催化循环这个项目的目标是了解结构和机制 第一个四个功能分配的成员出现的基础上， 生物信息学分析，是一个大的和通用的新的酶家族。人们期望 理解家庭的功能性原则可能会使新家庭成为一个 用于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.