The mechanistic enzymology of thiamin biosynthesis

硫胺素是人类饮食的重要组成部分，RDA为1.2 mg。也是重要 它是一种商业化学品，广泛用作食品添加剂和调味剂。年产量， 化学合成，大约有3,300吨。硫胺素依赖酶在 碳水化合物和支链氨基酸代谢。在这个时候，我们对这一点的机械理解 这类酶很复杂相比之下，虽然硫胺素是第一种被发现的维生素， 对它的生物合成的理解仍然是不完全的，因为生物合成途径是复杂的， 涉及前所未有的化学反应。我们研究的长期目标是完全的机械化 了解硫胺素生物合成的酶学，补救和catenation，在所有形式的生命和 说明硫胺素代谢和细胞生理学其他方面之间的联系。 在下一个资助期，我们描述了旨在阐明硫胺素生物合成的研究 细菌和真核生物中的噻唑和嘧啶。这些杂环形成反应涉及新颖的 生物化学我们的策略将包括动力学、修饰底物、蛋白质 诱变和结构研究。我们还将确定与硫胺素分解有关的基因， 打捞人体消化道中含有这些基因的细菌很可能在 控制人体硫胺素RDA。最后，我们将探索18F-硫胺素作为PET显像剂的用途， 最终确定健康人和患病人的全球硫胺素分布。 相关性（参见说明）： 硫胺素（维生素B1）是所有生命形式所必需的。我们的研究将促进商业化生产 发酵生产硫胺素，在新型抗生素的设计中具有潜在的应用价值。理解 维生素B1的回收和治疗将使我们能够评估这些活动在人类中的重要性。 消化道18F-硫胺素作为一种显像剂，在基础人类生物学和肿瘤中具有潜在的用途 裂解作用. '.

Thiamin is an essential component of the human diet with an RDA of 1.2 mg. It is also an important commercial chemical and it is w/idely used as a food additive and flavoring agent. Annual production, by chemical synthesis, is on the order of 3,300 tons. Thiamin-dependent enzymes play an important role in carbohydrate and branched-chain amino acid metabolism. At this time, our mechanistic understanding of this class of enzymes is sophisticated. In contrast, while thiamin was the first vitamin identified, our understanding of its biosynthesis is still incomplete because the biosynthetic pathway is complex and involves unprecedented reaction chemistry. The long-term goal of our research is the complete mechanistic understanding ofthe enzymology of thiamin biosynthesis, salvage and catabolism, in all forms of life and the elucidation of connections between thiamin metabolism and other aspects of cellular physiology. In the next grant period, we describe studies designed to elucidate the biosynthesis ofthe thiamin thiazole and pyrimidine in both bacteria and eukaryotes. These heterocycle forming reactions involve novel biological chemistry. Our strategy will involve a combination of kinetics, modified substrates, protein mutagenesis and structural studies. We will also identify the genes involved in thiamin breakdown and salvage. Bacteria, in the human digestive tract, containing these genes are likely to play an important role in controlling the human thiamin RDA. Finally, we will explore the use of 18F-thiamin as a PET imaging agent, ultimately to determine the global thiamin distrubution in healthy and diseased humans. RELEVANCE (See instructions): Thiamin (vitamin B1) is essential for all forms of life. Our studies will facilitate the commercial production of thiamin by fermentation and have potential applications in the design of new antibiotics. Understanding thiamin catabolism and salvage will enable us to evaluate the importance of these activities in the human digestive tract. 18F-thiamin has potential use, as an imaging agent, in basic human biology and in tumor rifitfictinn. . '.