STRUCTURE AND FUNCTION OF UNIQUE NON-HEME IRON DIOXYGENASES

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 拟议的XAS实验是旨在表征非血红素Fe(II)双加氧酶家族的两个成员的反应机制的项目的一部分，这两个成员是AlkB同源2(ABH2，与纽约大学医学院的Max Costa教授合作)和半胱氨酸双加氧酶(CDO)。具体地说，我们试图用XAS来阐明Ni(II)离子抑制AlkB从而产生高甲基化DNA的机制，这反过来又会导致癌症和遗传缺陷。其次，我们试图了解半胱氨酸和半胱胺在CDO的氧化还原化学中所起的作用。在ABH2的情况下，XAS将提供一些关于顺序反应机理的信息(a-酮戊二酸的结合，不结合，但在底物结合时改变铁的几何结构，以及氧活化)，与来自Ni(II)络合物的类似数据相比较，将导致对反应机理和Ni(II)抑制酶的机理的详细理解。在CDO的情况下，将讨论半胱氨酸和半胱胺作为还原剂和/或配体的作用。通过比较和对比这些酶的作用机制，我们希望进一步了解自然界是如何调节非血红素Fe(II)酶的活性部位的，以便催化这一酶家族的各种不同的反应。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The proposed XAS experiments are part of a project aimed at characterizing the reaction mechanisms of two members of the nonheme Fe(II) dioxygenase family of enzymes, AlkB homologue 2 (ABH2, in collaboration with Prof. Max Costa, NYU School of Medicine) and cysteine dioxygenase (CDO). Specifically, we seek to use XAS to elucidate the mechanism by which Ni(II) ions inhibit AlkB and thus produce hypermethylated DNA, which in turn can cause cancer and lead to genetic defects. Second, we seek to understand the role played by cysteine and cysteamine in the redox chemistry of CDO. In the case of ABH2, XAS will provide some of the information regarding the sequential reaction mechanism (binding of a-ketoglutarate, not binding but change the iron geometry upon substrate binding, and oxygen activation) which in comparison with similar data from the Ni(II) complex will lead to a detailed understanding of the reaction mechanism and the mechanism by which Ni(II) inhibits the enzyme. In the case of CDO, the roles of cysteine and cysteamine as reductants and/or ligands will be addressed. By comparing and contrasting the mechanisms of these enzymes, we hope to further the understanding of how nature tunes the active sites of non-heme Fe(II) enzymes in order to catalyze the wide variety of different reactions that is a feature of this enzyme family.