BIOSYNTHESIS OF ARA-A, 2'-DEOXYCOFORMYCIN AND ANALOGUES

这一更新建议是一个建议的合作继续 大卫教授的实验室之间的努力。 贝克， 教授 Robert J. Suhadolnik阐明了生物合成途径， 一组重要的药用核苷，包括ara-A和2 '- 脱氧共福霉素（2 '-dCF）。 前者是临床上有用的抗病毒药物 （抗疱疹剂），后者是腺苷的有效抑制剂 脱氨酶，最近发现是临床实用的， 治疗毛细胞白血病 本提案的目标是 (1)通过定义ara-A的生物合成途径， 腺苷的2 '-差向异构化的机制，目前 假设是一个自由基的过程或一个涉及NAD 在氧化还原过程中。 详细研究了腺苷2 '- 差向异构酶，包括用光亲和性探测其活性位点 标签和克隆酶的基因，计划。 （二） 阐明腺苷转化为2 '-dCF的精确途径。 计划概述，其中中间体在生物合成将是 通过现代光谱方法分离并充分表征， 用稳定同位素标记的化合物的辅助。 此类研究 将用于阐明2 '-dCF中其他核苷的途径 coformycin家族，包括2 '-氯-2'-脱氧coformycin和coformycin。 这些类似物之间的生物合成途径的相互关系将 被识破 CF氯化生成2 '-CldCF的机理将 下定决心。 酶，8-酮-2 '-dCF还原酶，其还原8- 将详细研究酮脱氧共形霉素与2 '-dCF的反应，目的是 用光亲和标记探测活性位点，并克隆用于 将酶转化为S. 橄榄色。 后者被认为是 通过目前可用的化学品生产2 '-dCF的可能用途 该合成涉及8-酮基-2 '-dCF的非特异性还原。 (3)阐明了一组相关化合物的生物合成， 包括癸烯醇，2 '-dCF的环戊烯基类似物;氮杂卓霉素， 1，4-二氮杂;和杀核素，一种含氟代糖的核苷。

This renewal proposal is a proposed continuation of the collaborative efforts between the laboratory of Prof. David C. Baker and that the Prof. Robert J. Suhadolnik to elucidate the biosynthetic pathways to a group of medicinally important nucleosides, which includes ara-A and 2'- deoxycoformycin (2'-dCF). The former is a clinically useful antiviral (antiherpes agent), and the latter is a potent inhibitor of adenosine deaminase that has recently been found to be of clinical utility in the treatment of hairy-cell leukemia. Goals of the current proposal are to (1) Conclude our studies on the biosynthesis of ara-A by defining the mechanism for the 2'-epimerization of adenosine, which is currently postulated to be either a free-radical process or one which involves NAD in a redox process. Detailed studies on the enzyme, adenosine 2'- epimerase, including the probing of its active site with photoaffinity labels and the cloning of the gene for the enzyme, are planned. (2) Elucidate the precise pathway by which adenosine is converted to 2'-dCF. Plans are outlined whereby intermediates in the biosynthesis will be isolated and fully characterized via modern spectroscopic methods, with the assistance of compounds labeled with stable isotopes. Such studies will serve to elucidate the pathways to other nucleosides in the 2'-dCF family, including 2'-chloro-2'-deoxycoformycin and coformycin. Interrelationships in the biosynthetic pathways among these analogues will be discerned. The mechanism for chlorination of CF to give 2'-CldCF will be determined. The enzyme, 8-keto-2'-dCF reductase, which reduces 8- ketodeoxycoformycin to 2'-dCF will be studied in detail, with the aim of probing the active site with photoaffinity labels and cloning the gene for producing the enzyme into S. lividans. The latter is considered of possible utility in producing 2'-dCF via the currently available chemical synthesis which involves a nonspecific reduction of the 8-keto-2'-dCF. (3) Elucidate the biosynthesis of a group of related compounds which includes adecypenol, a cyclopentenyl analogue of 2'-dCF; azepinomycin, a 1,4-diazepine; and nucleocidin, a fluorosugar-containing nucleoside.