Spectroscopic Studies of Mononuclear Non-Heme Fe Enzymes

描述（由申请人提供）：单核非血红素铁酶催化广泛的反应，包括高自旋亚铁位点的O2活化或高自旋铁位点的底物活化。最近，一类非血红素铁酶也被定义为具有硫代酸盐结扎。这些酶与遗传性疾病（苯丙酮尿症、丙酮尿症）直接相关，参与抗生素、内酰胺酶抑制剂、白三烯和脂质的生物合成，在DNA烷基化损伤的修复中起重要作用，并用于某些癌症的治疗。非血红素铁酶通常比血红素酶更难研究。新的光谱方法（强调变温度、变场磁圆二色性、金属K边、l边和配体K边x射线吸收光谱）已经和正在发展，使这些酶的详细研究成为可能。这些光谱数据支持的密度泛函理论计算提供了对电子结构的进一步了解，并允许评价反应坐标。本研究的目标是：1)直接探测亚铁活性位点及其与底物、辅因子等相关因子的相互作用，在分子水平上阐明催化机理；2)了解共底物结合如何引发亚铁中心与O2的反应；3)从实验和理论上了解氧中间体的性质和控制其反应性的因素；4)确定非血红素与血红素铁在激活O2中的关系；5)了解氧化铁中心激活底物的性质，并确定导致芳环裂解选择性的因素；6)确定高共价硫酸盐S-Fe（ll）键对半胱氨酸配体非血红素铁酶的不同反应性的贡献。相关性：非血红素铁酶与多种疾病相关，包括动脉硬化、癌症（缺氧调节）和神经系统疾病（阿尔茨海默病、帕金森病等）。由于这些酶在抗生素（青霉素、头孢菌素、万古霉素）的生物合成、抗癌活性（博莱霉素）、DNA修复和污染物（包括多氯联苯）的生物修复中发挥作用，因此它们在疾病的治疗和预防中也极为重要。这些研究提供了对这些酶的作用模式的基本理解，使策略能够改善或抑制功能并增强药物设计。

DESCRIPTION (provided by applicant): Mononuclear non-heme iron enzymes catalyze a wide range of reactions which either involve O2 activation by a high-spin ferrous site or substrate activation by a high-spin ferric site. Recently a class of non-heme iron enzymes that has thiolate ligation has also been defined. These enzymes are directly related to genetic disorders (phenylketonuria, alkaptonuria), involved in the biosynthesis of antibiotics, lactamase inhibitors, and leukotrienes and lipoxins, important in the repair of DNA alkylation damage, and utilized in the treatment of certain cancers. Non-heme iron enzymes have generally been far more difficult to study than heme enzymes. New spectroscopic methods (emphasizing variable-temperature, variable-field magnetic circular dichroism, and metal K- and L-edge and ligand K-edge X-ray absorption spectroscopy) have been and are being developed which enable the detailed study of these enzymes. Density functional theory calculations supported by these spectroscopic data provide further insight into electronic structure and allow evaluation of reaction coordinates. The goals of this research are to: 1) directly probe the ferrous active sites and their interactions with substrate, cofactor and other relevant factors to elucidate catalytic mechanisms on a molecular level; 2) understand how cosubstrate binding initiates the reaction of the ferrous center with O2; 3) experimentally and theoretically understand the nature of oxygen intermediates and factors that control their reactivity; 4) determine how non-heme relates to heme iron in activating O2; 5) understand the nature of substrate activation by an oxidized iron center, and define the factor(s) leading to selectivity in aromatic ring cleavage; 6) determine the contributions of the highly covalent thiolate S-Fe(lll) bond to the different reactivities of the cysteine liganded non-heme iron enzymes. RELEVANCE: The non-heme iron enzymes are associated with a wide range of diseases including arteriosclerosis, cancer (regulation of hypoxia) and neurological disorders (Alzheimer's, Parkinson's, etc.). These enzymes are also extremely important in the treatment and prevention of disease due to their roles in the biosynthesis of antibiotics (penicillins, cephalosporins, vancomycin), anti-cancer activity (Bleomycin), DNA repair and the bioremediation of pollutants (including PCBs). These studies provide a fundamental understanding of the modes of action of these enzymes enabling strategies to improve or inhibit function and enhance drug design.