Madyastha K M, Sridhar G R
Department of Organic Chemistry, Indian Institute of Science, Bangalore, India.
Biochem Biophys Res Commun. 1998 Aug 10;249(1):178-81. doi: 10.1006/bbrc.1998.9102.
A new oxidative pathway for the degradation of caffeine(1,3,7-Trimethylxanthine, I) by a mixed culture consisting of strains belonging to the genera Klebsiella and Rhodococcus is presented. The mixed culture does not initiate degradation by N-demethylation either complete or partial, but instead carries out oxidation at the C-8 position resulting in the formation of 1,3,7-trimethyluric acid (TMU, II) which further gets degraded to 3,6,8-trimethylallantoin (TMA, III). Both TMU and TMA are hitherto not shown to be formed in the microbial system. Further degradation of TMA (III) by caffeine grown cells yields dimethylurea (VII) as one of the metabolites. Oxygen uptake studies indicated that caffeine(I) grown cells oxidized TMU(II), TMA (III), glyoxalic acid (VI), dimethylurea(VII), and monomethylurea(V), but not monomethyl and dimethyluric acids. The mixed culture does not accept theophylline(1,3-dimethylxanthine), theobromine(3,7-dimethylxanthine), and paraxanthine(1,7-dimethylxanthine) as the carbon source.
本文介绍了一种由克雷伯氏菌属和红球菌属菌株组成的混合培养物降解咖啡因（1,3,7-三甲基黄嘌呤，I）的新氧化途径。该混合培养物不是通过完全或部分N-去甲基化来启动降解，而是在C-8位进行氧化，生成1,3,7-三甲基尿酸（TMU，II），TMU进一步降解为3,6,8-三甲基尿囊素（TMA，III）。迄今尚未表明TMU和TMA会在微生物系统中形成。咖啡因生长的细胞对TMA（III）的进一步降解产生二甲基脲（VII）作为代谢产物之一。氧气摄取研究表明，咖啡因（I）生长的细胞可氧化TMU（II）、TMA（III）、乙醛酸（VI）、二甲基脲（VII）和一甲基脲（V），但不能氧化一甲基尿酸和二甲基尿酸。该混合培养物不接受茶碱（1,3-二甲基黄嘌呤）、可可碱（3,7-二甲基黄嘌呤）和对黄嘌呤（1,7-二甲基黄嘌呤）作为碳源。
