INVIVO AND ENZYMATIC CONVERSION OF TOYOCAMYCIN TO SANGIVAMYCIN BY STREPTOMYCES-RIMOSUS
INVIVO AND ENZYMATIC CONVERSION OF TOYOCAMYCIN TO SANGIVAMYCIN BY STREPTOMYCES-RIMOSUS
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DOI：
10.1016/0003-9861(74)90223-9
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发表时间：
1974-01-01
影响因子：
3.9
通讯作者：
SUHADOLNIK, RJ
中科院分区：
文献类型：
--
作者：
UEMATSU, T;SUHADOLNIK, RJ
从14种链霉菌的培养滤液中分离到吡咯嘧啶核苷、托卡霉素、生根霉素和杀菌素。虽然早期的实验表明，吡咯嘧啶核苷的生物合成需要GTP作为共同的前体，但没有实验证据证明这些天然存在的核苷类似物之间存在相互转化。这里提供的数据描述了两种类型的实验，以证明托伊卡霉素是圣维菌素的前体。首先，在活体实验中，放射性的托伊卡霉素被转化为圣维菌素。其次，从可溶组分OFS中分离和部分纯化了催化交链霉素转化为桑白霉素的酶，即交链霉素腈水解酶。在合成杀菌素或托卡霉素的链霉菌的无细胞提取物中不存在氰基水解酶。活性可以通过测量从托伊卡霉素中生成放射性圣维菌素来检测。该酶已纯化24倍，总收率为5%。最适pH为6.5，最适Km值为0.5 mM。大多数被测试的腈都是竞争性抑制剂，但它们不是底物。水解酶的活性仅限于将氰基转化为羧基团。水解酶活性在细胞壁中观察到。在开始生产托洛霉素之前使用Rimosus。在活体研究中，体外研究表明，托伊卡霉素不是杀结核蛋白的前体。实验证据有力地表明，吡咯嘧啶核苷抗生素的生物合成过程中肯定存在一个分支点。
The pyrrolopyrimidine nucleosides, toyocamycin, sangivamycin, and tubercidin are isolated from the culture filtrates of 14 species of theStreptomyces.Although earlier experiments showed that the biosynthesis of the pyrrolopyrimidine nucleosides require GTP as the common precursor, there was no experimental evidence to demonstrate the interconversion of these naturally occurring nucleoside analogs. The data presented here describe two types of experiments to prove that toyocamycin is the precursor for sangivamycin. First,in vivoexperiments show that radioactive toyocamycin is converted to sangivamycin. Second, the enzyme, toyocamycin nitrile hydrolase, that catalyzes the conversion of toyocamycin to sangivamycin has been isolated and partially purified from the soluble fraction ofS. rimosus.The nitrile hydrolase is not present in cell-free extracts of theStreptomycesthat synthesize tubercidin or toyocamycin. Activity can be assayed by measuring the formation of radioactive sangivamycin from toyocamycin. The enzyme has been purified 24-fold with an over-all yield of 5%. The pH optimum is 6.5 and theKmis 0.5 mm. Most nitriles tested are competitive inhibitors but they are not substrates. The activity of the hydrolase is limited to the conversion of the nitrile group to the carboxamide group. Hydrolase activity is observed in cell-frre estracts ofS. rimosusbefore toyocamycin production begins. Thein vivoandin vitrostudies demonstrate that toyocamycin is not a precursor for tubercidin. The experimental evidence strongly suggests that there must be a branch point in the biosynthesis of the pyrrolopyrimidine nucleoside antibiotics.