The Influence of Primary Coordination Sphere in Aromatic C-C Ring Scission: Mechanistic Studies of 3-His Coordinated Non-heme Iron Enzymes

在化学系生命过程化学(CLP)项目的支持下，纽约市立大学斯塔滕岛学院的Rupal Gupta博士将研究铁酶对芳香有机分子的生物降解。导致这些化合物分解的化学反应的焦点是一个铁中心，它通过在大多数铁酶中普遍存在的支架与蛋白质相连。然而，最近已经发现了几种新型的铁结合支架。这些非典型结合位点对酶的活性、效率和选择性的影响尚不清楚。建议的研究将以系统的方式评估金属结合支架对酶功能的作用。这些研究的发现将为人工催化剂的设计提供参考，并为自然界进行的具有挑战性的化学反应提供见解。这个项目还将有助于对本科生和高中生进行严格的培训，他们将通过外展项目向他们介绍生物化学、酶学和光谱学的概念，并将获得进行基于课程的研究的机会。催化大量化学反应的非血红素铁酶通常带有一个金属结合基序，由两个组氨酸和一个羧酸残基(2-His-1-Cxylate)组成。最近，人们发现了一些非典型的金属结合基序，如3-His、3-His-1-Cxylate和4-His。主配位球的这种变化明显改变了金属中心的配位场，预计将影响铁中心进行的催化。这个项目的总体目标是系统地了解初级配位球对执行C-C环断裂的非血红素铁酶的反应活性和催化作用的影响。利用生化和光谱相结合的方法，研究3-组氨酸芳环裂解酶的反应机理，重点确定初级配位球对反应动力学和反应中间产物的电子和磁学性质的影响。这些研究将有助于评估非典型金属结合基序的性质及其对反应性和底物选择性的影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Chemistry of Life Processes (CLP) Program in the Chemistry Division, Dr. Rupal Gupta from the College of Staten Island, City University of New York will investigate the biological degradation of aromatic organic molecules by iron enzymes. The focal point of chemical reactions responsible for the decomposition of these compounds is an iron center that is tethered to the protein via a scaffold ubiquitously found in most iron enzymes. However, several novel iron-binding scaffolds have been recently identified. The influence of these atypical binding sites on enzymatic reactivity, efficiency and selectivity is not clear. The proposed studies will evaluate the role of metal binding scaffolds toward enzymatic function in a systematic manner. Findings from these studies will inform the design of artificial catalysts and offer insights into the challenging chemical reactions performed by Nature. This project will also contribute to the rigorous training of undergraduates and high school students, who will be introduced to concepts of biochemistry, enzymology and spectroscopy through outreach programs and will be offered opportunities to conduct curriculum-based research. Non-heme iron enzymes that catalyze a myriad of chemical reactions typically bear a metal-binding motif composed of two histidine and one carboxylate residues (2-His-1-carboxylate). Recently, several atypical metal binding motifs such as 3-His, 3-His-1-carboxylate and 4-His, have been identified. Such variations in the primary coordination sphere that clearly alter the ligand field at the metal center are expected to influence the catalysis carried out by the iron center. The overall goal of this project is to gain a systematic understanding of the influence of the primary coordination sphere on the reactivity and catalysis of non-heme iron enzymes performing C-C ring scission. By utilizing a combination of biochemical and spectroscopic methodologies, reaction mechanisms of 3-His aromatic ring cleaving enzymes will be investigated with a focus on identifying the influence of the primary coordination sphere on reaction kinetics and, electronic and magnetic properties of the reaction intermediates. These studies will help evaluate the properties of atypical metal binding motifs and their impact on the reactivity and substrate selectivity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.