Studies on Enzyme Mechanism and Inhibitor Design

这项提案分为三个部分。第一部分描述了我们对产生生物碱的酶的研究。生物碱是含氮的天然产物，主要由植物和真菌产生。它们往往具有强大的生物活性，许多已被用作有价值的药物(吗啡/疼痛、长春花碱/癌症、麦角胺/偏头痛)。我们正在研究与生物合成吲哚生物碱有关的酶，如麦角胺。我们已经发现，这些酶可以产生可能具有独特生物学特性的新型生物碱。通过了解这些酶的功能细节，我们可能能够利用它们来生产新的生物活性化合物。**第二部分涉及对导致溃疡和食物中毒的病原菌中孟喹酮(维生素K2)的生物合成的研究。这些细菌需要麦喹酮进行呼吸，没有它它们就不能生存。我们正在研究这些生物体中参与孟喹酮生物合成的酶，因为这些酶是有吸引力的抑制剂设计的目标。这样的抑制剂会阻止酶的运行，因此会成为对抗这些微生物的抗生素。在我们最初的研究中，我们概述了这种维生素形成的正确生物合成途径，在正在进行的工作中，我们正在研究该途径中的单个酶，以便可以设计抑制剂。**第三部分涉及微管蛋白修饰酶的研究。微管构成了人类细胞的细胞骨架，对细胞的正常分裂是必不可少的。出于这个原因，干扰正常微管形成的化合物可以作为有效的抗癌药物(长春花碱、紫杉醇)。微管是由微管蛋白自发自组装而形成的。我们正在研究一组酶，它们可以对微管蛋白进行化学修饰，从而控制其物理性质。我们正在准备干扰这些酶作用的抑制分子，我们预计这些化合物将具有细胞毒性。这可能会成为治疗癌症的一种新方法。

This proposal is divided into three sections. The first section describes our studies on enzymes that produce alkaloids. Alkaloids are nitrogen-containing natural products primarily produced by plants and fungi. They often possess potent biological activities and many have been used as valuable pharmaceuticals (morphine/pain, vinblastine/cancer, ergotamine/migraines). We are studying the enzymes involved in the biosynthesis of the indole alkaloids such as ergotamine. We have discovered that these enzymes can produce novel alkaloids that may have unique biological properties. By understanding the details of how these enzymes function, we may be able to utilize them in the production of new bioactive compounds.** The second section involves studies on the biosynthesis of menaquinone (vitamin K2) in the pathogenic bacteria that are responsible for ulcers and food poisoning. These bacteria require menaquinone for respiration and without it they cannot survive. We are investigating the enzymes involved in menaquinone biosynthesis in these organisms since these are attractive targets for inhibitor design. Such inhibitors would prevent the enzymes from operating and would therefore serve as antibiotics against these organisms. In our initial studies we outlined the correct biosynthetic pathway for the formation of this vitamin, and in ongoing work we are studying individual enzymes in the pathway so that inhibitors can be designed.** The third section involves studies on tubulin-modifying enzymes. Microtubules form the cytoskeleton of human cells and are absolutely required for proper cell division. For this reason, compounds that interfere with proper microtubule formation act as potent anticancer agents (vinblastine, taxol). Microtubules are generated by the spontaneous self-assembly of tubulin. We are studying a group of enzymes that chemically modify tubulin and therefore control its physical properties. We are preparing inhibitor molecules that will interfere with the action of these enzymes and we anticipate that such compounds will be cytotoxic. This could potentially serve as a new approach towards treating cancer.******