Carbapenem Biosynthesis: Confirmation of Stereochemical Assignments and the Role of CarC in the Ring Stereoinversion Process from <scp>l</scp>-Proline
作者:Anthony Stapon、Rongfeng Li、Craig A. Townsend
DOI:10.1021/ja034248a
日期:2003.7.1
5R)-carbapenam carboxylic acid or the final carbapenem product. CarC, the third enzyme of the biosynthetic pathway required to synthesize the carbapenem, was demonstrated in cell-free studies to be dependent on alpha-ketoglutarate and ascorbate in keeping with weak sequence identities with other non-heme iron, alpha-ketoglutarate-dependent oxygenases. CarC mediated the stereoinversion of synthetic (3S
(5R)-Carbapen-2-em-3-羧酸是天然存在的碳青霉烯β-内酰胺抗生素中结构最简单的。它与两种饱和的 (3S,5S)- 和 (3S,5R)-碳青霉烯羧酸共存。在本文中解决的关于这些化合物的旋转符号和绝对构型的文献中仍然存在混淆。(3S,5S)-Carbapenam 羧酸是从 L-焦谷氨酸制备的,以明确确定其绝对构型与从粘质沙雷氏菌中分离的天然产物和大肠杆菌中生物合成基因 carAB 的过表达相同。在非对映异构 C-5 亚甲基位点用氘或氚标记的 L-脯氨酸显示在 (3S,5S)-碳青霉烯羧酸的桥头处结合了一个标记,但未结合到“倒置”(3S,5R)-碳青霉烯羧酸或最终的碳青霉烯产品。CarC 是合成碳青霉烯所需的生物合成途径的第三种酶,在无细胞研究中被证明依赖于 α-酮戊二酸和抗坏血酸,与其他非血红素铁、α-酮戊二酸依赖性加氧酶的弱序列同一性一致. CarC 介导合成的 (3S,5S)-碳青霉烯羧酸立体转化为