Probing a Novel Mechanism of Cholinesterase Inactivation by Phosphorothiolates

本研究的长期目标是了解磷硫酸盐（带有P-S-R基团的有机磷化合物）中存在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。异马拉硫磷是在马拉硫磷中发现的一种磷硫酸盐杂质，在碳和磷上都有不对称中心，是研究与各种胆碱酯酶相互作用的一个很好的起点。一个共同的目标是制备新的手性磷硫酸盐结构，能够探测胆碱酯酶的功能。尽管近年来对胆碱酯酶的三维结构的了解进展迅速，但立体化学精密活性位点探针和灭活剂的开发却滞后。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、立体异构对机理的影响以及胆碱酯酶结构和功能的认识。在这项研究中，将实现两个具体目标；(1)确定异马拉硫磷灭活胆碱酯酶的机制；(2)利用异马拉硫磷固有的特定化学设计特征，结合结构-反应性关系，设计并制备基于磷硫酸盐的p手性抗胆碱酯酶药物，测试双阶段抑制机制的范围。一个严重的化学问题一直是公众关注的焦点；“有机磷（OP）杀虫剂（如马拉硫磷、二嗪农等）安全吗？如果不安全，哪些关键的相互作用与毒性作用有关？它们是否容易识别？”为了解决和回答这个问题，需要对有机磷作用模式的化学和生化机制有一个基本的了解。虽然OP的作用机制被广泛理解，但对于OP分子的“左旋”或“右旋”或对称性如何改变其性质，我们知之甚少。这项研究就是为了寻求这样一种理解。

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.