Studies on RNA Cleavage: Catalyst Design and Mechanism

这个奖项在无机，生物无机和有机化学计划支持研究珍妮特R。位于布法罗的纽约州立大学化学系的莫罗和约翰·P·理查德说。他们将设计催化剂来切割RNA和DNA，并试图确定这些切割反应的机制。 该项目有三个主要组成部分。 首先，将制备新的Zn（II）和Th（IV）双核配合物。 这些将具有可变的桥接配体以控制金属离子的几何形状和分离。研究人员还将在化合物中使用其他金属离子的各种组合，包括Cd，Cu，Ni，Pb和In。 接下来，模型RNA底物将用于反应性研究，以确定不同金属络合物提供过渡态稳定的位点。结构-反应性对催化活性的影响将用于区分在氧膦样过渡态与亲核2 '-羟基相互作用的金属络合物和在该过渡态与氧离去基团相互作用的络合物。 将检查RNA切割的机制，以确定是否存在离去基团和进入的亲核试剂的同时活化，或者是否存在通过螯合非桥接氧而在离去基团/亲核试剂处没有相互作用的“双重”刘易斯酸活化。 分析和计算方法将被开发，以检查金属-金属距离，几何形状和RNA裂解的催化活性之间的关系。 本研究的第三部分将集中于在类似于RNA的底物上切割3 '-磷酸二酯键的酸碱催化，以区分发生在离去基团/亲核试剂处的酸碱催化和亲电催化在磷酸基团的非桥接氧处。RNA的切割剂最终可能具有实际的治疗应用，但在这一点上提出了大量的智力挑战。 该反应的机理还没有很好地理解，因此裂解剂的最佳设计特征是未知的。 在本研究中，各种双核金属配合物将被用作裂解剂，并确定其作用机制。 还将考虑酸碱机制的作用。 研究生和本科生将受益于参与这个跨学科的项目，包括有机和无机合成和动力学参数的测定。学生将参加纽约州立大学布法罗分校的化学生物学课程，并由具有广泛技能的调查人员团队指导。

This award in the Inorganic, Bioinorganic, and Organometallic Chemistry Program supports research by Janet R. Morrow and John P. Richard of the Chemistry Department, State University of New York at Buffalo. They will design catalysts to cleave RNA and DNA and attempt to determine the mechanism of these cleavage reactions. There are three main components to the project. First, new Zn(II) and Th(IV) dinuclear complexes will be prepared. These will have variable bridging ligands to control the geometry and separation of the metal ions. The investigators will also use various combinations of other metal ions in the compounds, including Cd, Cu, Ni, Pb, and In. Next, model RNA substrates will be used in reactivity studies to determine the site(s) at which different metal complexes provide transition state stabilization. Structure-reactivity effects on catalytic activity will be used to distinguish metal complexes that interact with the nucleophilic 2'-hydroxyl at the oxyphosphorane-like transition state from complexes that interact with the oxygen leaving group at this transition state. The mechanism of RNA cleavage will be examined to determine whether there is simultaneous activation of both the leaving group and incoming nucleophile, or if there is "double" Lewis acid activation by chelation of the nonbridging oxygens, with no interactions at the leaving group/nucleophile. Analytical and computational methods will be developed to examine relationships between metal-metal distance, geometry, and catalytic activity for cleavage of RNA. The third part of the study will focus on acid-base catalysis of the cleavage of the 3'-phosphodiester linkage at substrates that resemble RNA in order to distinguish acid-base catalysis that occurs at the leaving group/nucleophile from electrophilic catalysis at the nonbriding oxygens of the phosphate group. Cleavage agents for RNA may eventually have practical therapeutic applications, but at this point present substantial intellectual challenges. The mechanism of the reaction is not well understood and so the optimal design features of a cleavage agent are unknown. In this study, various dinuclear metal complexes will be used as cleavage agents and their mechanism of action determined. The role of acid-base mechanisms will also be considered. Graduate and undergraduate students will benefit from involvement in this interdisciplinary project that includes organic and inorganic synthesis and the determination of kinetic parameters. Students will participate in the Chemical Biology program at SUNY-Buffalo and be mentored by a team of investigators with a wide range of skills.