A C-methyltransferase involved in methyl-branch formation in sugars has been characterized for the first time. TylC3, an (S)-adenosylmethylthionine(AdoMet)-dependent enzyme, catalyzes the attachment of a methyl branch [Eq. (1)] in the biosynthesis of L-mycarose, an unusual sugar found in tylosin and as its O-3-methyl derivative in erythromycin. The C-3 methylation proceeds with inversion of configuration and does not require the assistance of any cofactors. The turnover rate is 1.4±0.1 min-1 . TDP=thymidine-5'-dihydrogenphosphate.
Biosynthesis of Mycarose: Isolation and Characterization of Enzymes Involved in the C-2 Deoxygenation
作者:Huawei Chen、Gautam Agnihotri、Zhihong Guo、Nanette L. S. Que、Xuemei H. Chen、Hung-wen Liu