ASSESSING THE CORE STRUCTURE OF A STABLE PEROXO DIIRON INTERMEDIATE IN THE AMINE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 AurF是硫代链球菌的一种新的加氧酶，它催化对氨基苯甲酸(PABA)不寻常的6电子氧化生成对硝基苯甲酸(PNBA)，对硝基苯甲酸是抗生素金黄色的重要结构成分。我们已经证明AurF是参与许多生物氧化反应(如可溶性甲烷单加氧酶)的双核非血红素铁酶的成员。结合生化、动力学和光谱技术，我们在该反应中鉴定了一种化学活性过氧二铁(III/III)中间体。在没有底物PABA的情况下，这种中间体积累到接近化学计量比的量，但它很容易氧化底物。过氧二铁(III/III)中间体与其他特征良好的过氧二铁(III/III)相比具有明显不同的光谱参数，这些过氧二铁被认为具有？-1，2-过氧基团。它的光学跃迁(可能是过氧化氢到铁的电荷转移带)在500 nm附近观察到，它的穆斯堡尔异构体位移β=0.50 mm/S。-1，2-过氧基二铁(III/III)中间体的穆斯堡尔异构体位移β&gt；S 0.60 mm/S，在~700 nm处有一个LMCT带。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. AurF, a novel oxygenase from S. thioluteus, catalyzes the unusual 6-electron oxidation of p- aminobenzoic acid (pABA) to p-nitrobenzoic acid (pNBA), an essential structural component of the antibiotic aureothin. We have demonstrated that AurF is a member of dinuclear non-heme- iron enzymes that are involved in numerous biological oxidation reactions (e.g. soluble methane monooxygenase). Using a combination of biochemical, kinetic, and spectroscopic techniques, we have identified a chemically competent peroxo-diiron(III/III) intermediate in this reaction. In the absence of substrate, pABA, this intermediate accumulates to nearly stoichiometric amounts, but it readily oxidizes the substrate. The peroxo-diiron(III/III) intermediate has markedly different spectroscopic parameters compared to other, well characterized peroxo-diiron(III/III) that are believed to have a ?-1,2-peroxo unit. Its optical transition (possibly a peroxide-to-iron charge transfer band) is observed around 500 nm, and it has a M¿ssbauer isomer shift of beta = 0.50 mm/s. ?-1,2-Peroxo-diiron(III/III) intermediates exhibit M¿ssbauer isomer shifts beta > 0.60 mm/s and a LMCT band at ~700 nm.