DESIGN OF INHIBITORS OF EPINEPHRINE BIOSYNTHESIS

苯乙醇胺N-甲基转移酶（PNMT，E.C.2.1.1.28）是 在生物合成中催化末端步骤的酶 肾上腺素 这种酶的水平增加，发现在 压力和高血压时期。 埃皮内什已经 与大脑中的许多神经调节过程有关。 我们已经证明，PNMT抑制剂可以降低血液中 自发性高血压大鼠的血压;然而， 目前可用的抑制剂显示α 2-肾上腺素能受体 这种拮抗作用也可能产生一些观察到的 药理作用 因此，我们建议设计更多 通过绘制PNMT来选择性抑制这种酶 活性位点（1）具有一些精心选择的结构和 构象探针（底物类似物，以探测 多个芳环结合位点的可能性，并探测 去甲肾上腺素在活性部位相互作用的方式 多底物抑制剂，通过 同时占据去甲肾上腺素和去甲肾上腺素底物位点， 死端抑制剂，以探测构象要求， 乙醇胺侧链的结合;和替代底物 抑制剂，以探索结合后的区域亲脂性效应），（2） 用转移NOE技术来探测 配体，当结合到PNMT，和（3）通过亲和标记的氨基 在活性位点的酸残基。 结果显示，所有三个子 项目将结合起来，以完善计算机图形模型， PNMT的活性位点，这是我们实验室开发的模型 （当与开发的类似模型集成时， α 2-肾上腺素能受体）将允许设计和合成 酶的选择性抑制剂。 这种抑制剂将是 一个有用的药理学工具，以探讨所发挥的作用， 中枢神经系统中的肾上腺素

Phenylethanolamine N-Methyltransferase (PNMT,E.C.2.1.1.28) is the enzyme that catalyzes the terminal step in the biosynthesis of epinephrine. Increased levels of this enzyme are found during periods of stress and in hypertension. Epinephrine has been implicated in a number of neuroregulatory processes in the brain. we have demonstrated that inhibitors of PNMT can lower blood pressure in spontaneously hypertensive rats; however, all of the inhibitors presently available show alpha 2-adrenergic receptor antagonism that could also produce some of the observed pharmacological effects. Therefore, we propose to design more selective inhibitors of this enzyme by mapping out the PNMT active site (1) with a few carefully selected structural and conformational probes (substrate analogues to probe the possibility of multiple aromatic ring binding sites and to probe the manner in which norepinephrine interacts at the active site of PNMT; multisubstrate inhibitors to enhance selectivity by occupying both the norepinephrine and AdoMet substrate sites, dead end inhibitors to probe the conformational requirements for binding of the ethanolamine side chain; and alternate substrate inhibitors to explore regional lipophilic effects upon binding), (2) with transferred NOE techniques to probe the conformation of ligands when bound to PNMT, and (3) by affinity labeling of amino acid residues at the active site. Results from all three sub- projects will be combined to refine a computer graphics model of the active site of PNMT, a model developed in our laboratories that (when integrated with a similar model to be developed for the alpha 2-adrenegic receptor) will allow the design and synthesis of a selective inhibitor of the enzyme. Such an inhibitor would be a useful pharmacological tool to probe the role played by epinephrine in the central nervous system.