Probing a Novel Mechanism of Cholinesterase Inactivation by Phosphorothiolates

本研究的长期目标是了解硫代磷酸盐(含P-S-R基团的有机磷化合物)中的不对称性如何调节胆碱酯酶失活和再激活的速度、程度和机制。异马硫磷是马拉硫磷中发现的一种硫代磷杂质，在碳和磷上都具有不对称中心，是研究与各种胆碱酯酶相互作用的良好起点。一个共同的目标是制备能够探测胆碱酯酶功能的新型手性硫代磷酸盐结构。尽管近年来对胆碱酯酶三维结构的研究进展很快，但对立体化学精确的活性部位探针和失活剂的开发却相对滞后。对这些新化合物的开发和需求将大大增加我们对溶液反应性、立体异构体对机理的影响以及胆碱酯酶结构和功能的了解。在这项研究中，有两个特定的目的：(1)确定异马硫磷对胆碱酯酶失活的机制；(2)利用异马硫磷固有的特殊化学设计特征，结合结构-反应关系，设计和制备P-手性硫代磷基抗胆碱酯酶药物，以测试两阶段抑制机制的范围。一个严重的化学问题一直处于公众关注的前沿；“有机磷(OP)杀虫剂(如马拉硫磷、二氮磷等)安全吗？如果不安全，哪些关键相互作用与有毒行为有关或相关，它们是否容易被识别？”为了解决和回答这个问题，需要对有机磷作用模式下的化学和生化机制有一个基本的了解。尽管OP的作用机制被广泛了解，但关于OP分子中的“左旋”或“右旋”或对称性如何改变其性质的了解很少。本研究旨在寻求这样的理解。

9808372ThompsonThe long-range objective of this research is to understand how asymmetry present in phosphorothiolates (organophosphorus compounds bearing a P-S-R group) regulates the rate, extent and mechanism of cholinesterase inactivation and reactivation. Isomalathion, a phosphorothiolate impurity found in malathion, bears centers of asymmetry at both carbon and phosphorus and is an excellent starting point for studying interactions with various cholinesterases. A co-objective is to prepare novel chiral phosphorothiolate structures capable of probing cholinesterase function. Although knowledge of the three-dimensional structure of cholinesterase has advanced rapidly in recent years, the needed development of stereochemically precise active site probes and inactivators has lagged behind. The development and demand for these novel compounds could add significantly to our knowledge of solution reactivity, effects of stereoisomerism on mechanism, and cholinesterase structure and function. In this study, two specific aims will be undertaken; (1) to determine the mechanism of cholinesterase inactivation by isomalathion, and (2) to use specific chemical design features inherent to isomalathion in combination with structure-reactivity relationships to design and prepare P-chiral phosphorothiolate-based anticholinesterase agents to test the scope of dual-stage inhibition mechanisms. A serious chemical problem has remained at the forefront of public concern; "Are organophosphorus (OP) insecticides (e.g., malathion, diazinon, etc.) safe, and if not, what key interactions are responsible or correlate with toxic action and can they be readily identified?" In order to address and answer this question, a basic understanding of the chemical and biochemical mechanisms underlying organophosphate mode of action is required. Although OP mechanism of action is widely understood, very little is known about how "left-" or "right-handedness" or symmetry in OP molecules alters their properties. This research is directed toward pursuing such an understanding.