BIOSYNTHESIS OF VITAMIN B1 AND VITAMIN B6

描述（改编自申请人摘要）：60多年后 吡哆醇（维生素B6）和硫胺素的发现和合成 （维生素B1）和认识到其营养的重要性，以及更多 在阐明它们的生化功能30多年后， 导致每种化合物的生物合成途径的知识仍然是 支离破碎 本提案的目的是进一步 阐明了两种维生素的生物合成，更具体地， 寻找它们代谢途径上的前体。 根据放射性示踪剂掺入研究的结果， 这表明两种维生素的碳链都是由 从碳水化合物前体，已经提出了工作假设， 解释了吡哆醇的生物合成机制， 硫胺素的两个亚基，并假定高级 中间体的 在目前的赠款期间，打算测试这些 提案 1-脱氧-D-木酮糖和4-羟基-L-苏氨酸将被 合成并在E.杆菌 三 将采用的方法，如果成功，将提供令人信服的 支持这两种化合物中间性的证据：（1） 在存在下从（6- 13 C）葡萄糖置换标记的掺入 1-脱氧-D-木酮糖和4-羟基-L-苏氨酸的未标记样品;（2） 掺入来自13 C-标记1-脱氧-D-木酮糖样品的标记， 4-羟基-L-苏氨酸;和（3）捕获3 H/14 C-标记的 1-脱氧-D-木酮糖和4-羟基-L-苏氨酸。大肠杆菌培养， 已经从3 H/14 C标记的甘油中产生了3 H/14 C标记的吡哆醇。 如果 1-脱氧-D-木酮糖被确认为中间体，其氧化产物， 2，4-二氧代戊烷-3，5-二醇将进行类似检测。 掺入 13 C-标记的1-脱氧-D-木酮糖进入噻唑核的C5链， 硫胺素和13 C标记的己糖进入嘧啶核 将进行测试，试图为悬而未决的问题提供答案， 他们的起源 越来越明显的是，B1和B2的主要前体 B6是常见的代谢物。 这是长期的目标这是长期的目标 调查，以确定在每个通路中被阻断的步骤， 哺乳动物组织，从而使化合物成为必需的膳食 件.

DESCRIPTION (adapated from applicant's abstract): More than 60 years after the discovery and synthesis of pyridoxine (vitamin B6) and of thiamin (vitamin B1) and the recognition of their nutritional importance, and more than 30 years after the elucidation of their biochemical functions, knowledge of the biosynthetic pathways leading to each compound is still fragmentary. The objectiveof the present proposal is the further elucidation of the biosynthesis of the two vitamins and, more specifically, the search for committed precursors on the metabolic route to each of them. Based on the results of incorporation studies with radioactive tracers, which showed that the carbon chains of each of the two vitamins are derived from carbohydrate precursors, working hypotheses have been put forward that account for the mechanism of biosynthesis of pyridoxine and of each of the two subunits of thiamin and that postulate structures of advanced intermediates. In the present grant period it is intended to test these proposals. 1-Deoxy-D-xylulose and 4-hydroxy-L-threonine will be synthesized and tested as precursors of pyridoxine in E. coli. Three approaches will be employed which, if successful, would provide compelling evidence in support of the intermediacy of these two compounds: (1) displacement of incorporation of label from (6-13C)glucose in the presence of unlabeled samples of 1-deoxy-D-xylulose and 4-hydroxy-L-threonine; (2) incorporation of label from 13C-labeled samples of 1-deoxy-D-xylulose and 4-hydroxy-L-threonine; and (3) trapping of 3H/14C-labeled 1-deoxy-D-xylulose and 4-hydroxy-L-threonine from an E. coli culture that has yielded 3H/14C-labeled pyridoxine from 3H/14C-labeled glycerol. If 1-deoxy-D-xylulose is confirmed as an intermediate, its oxidationproduct, 2,4-dioxopentane-3,5-diol, will be tested similarly. Incorporation of 13C-labeled 1-deoxy-D-xylulose into the C5 chain of the thiazole nucleus of thiamin and of specifically 13C-labeled hexoses into the pyrimidine nucleus will be tested in an attempt to provide answers to outstanding questions of their origin. It is becoming evident that the primary precursors of B1 and B6 are common metabolites. It is the long term objectiveof this investigation to identify the step in each pathway that is blocked in mammalian tissues, thereby making the compounds essential dietary components.