Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842-3012, United States.
J Am Chem Soc. 2011 Feb 23;133(7):2080-3. doi: 10.1021/ja110157u. Epub 2011 Jan 28.
Two enzymes of unknown function from the amidohydrolase superfamily were discovered to catalyze the deamination of N-6-methyladenine to hypoxanthine and methyl amine. The methylation of adenine in bacterial DNA is a common modification for the protection of host DNA against restriction endonucleases. The enzyme from Bacillus halodurans, Bh0637, catalyzes the deamination of N-6-methyladenine with a k(cat) of 185 s(-1) and a k(cat)/K(m) of 2.5 × 10(6) M(-1) s(-1). Bh0637 catalyzes the deamination of N-6-methyladenine 2 orders of magnitude faster than adenine. A comparative model of Bh0637 was computed using the three-dimensional structure of Atu4426 (PDB code: 3NQB) as a structural template and computational docking was used to rationalize the preferential utilization of N-6-methyladenine over adenine. This is the first identification of an N-6-methyladenine deaminase (6-MAD).
两个具有未知功能的酶，属于酰胺水解酶超家族，被发现可以催化 N-6-甲基腺嘌呤脱氨成为次黄嘌呤和甲胺。细菌 DNA 中的腺嘌呤甲基化是一种常见的修饰方式，可以保护宿主 DNA 免受限制内切酶的侵害。来自巴氏芽孢杆菌的酶 Bh0637 可以催化 N-6-甲基腺嘌呤脱氨，其 k(cat)为 185 s(-1)，k(cat)/K(m)为 2.5×10(6) M(-1) s(-1)。Bh0637 催化 N-6-甲基腺嘌呤的脱氨速度比腺嘌呤快 2 个数量级。使用 Atu4426（PDB 代码：3NQB）的三维结构作为结构模板，计算了 Bh0637 的比较模型，并通过计算对接来合理化其对 N-6-甲基腺嘌呤的优先利用超过腺嘌呤。这是首次鉴定出 N-6-甲基腺嘌呤脱氨酶（6-MAD）。
