Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster, Germany.
Appl Microbiol Biotechnol. 2010 Apr;86(3):791-804. doi: 10.1007/s00253-010-2455-0. Epub 2010 Feb 16.
Whereas the majority of O(2)-metabolizing enzymes depend on transition metal ions or organic cofactors for catalysis, a significant number of oxygenases and oxidases neither contain nor require any cofactor. Among the cofactor-independent oxidases, urate oxidase, coproporphyrinogen oxidase, and formylglycine-generating enzyme are of mechanistic as well as medical interest. Formylglycine-generating enzyme is also a promising tool for protein engineering as it can be used to equip proteins with a reactive aldehyde function. PqqC, an oxidase in the biosynthesis of the bacterial cofactor pyrroloquinoline quinone, catalyzes an eight-electron ring-closure oxidation reaction. Among bacterial oxygenases, quinone-forming monooxygenases involved in the tailoring of polyketides, the dioxygenase DpgC found in the biosynthesis of a building block of vancomycin and teicoplanin antibiotics, luciferase monooxygenase from Renilla sp., and bacterial ring-cleaving 2,4-dioxygenases active towards 3-hydroxy-4(1H)-quinolones have been identified as cofactor-independent enzymes. Interestingly, the 3-hydroxy-4(1H)-quinolone 2,4-dioxygenases as well as Renilla luciferase use an alpha/beta-hydrolase architecture for oxygenation reactions. Cofactor-independent oxygenases and oxidases catalyze very different reactions and belong to several different protein families, reflecting their diverse origin. Nevertheless, they all may share the common mechanistic concept of initial base-catalyzed activation of their organic substrate and "substrate-assisted catalysis".
虽然大多数 O(2)-代谢酶依赖过渡金属离子或有机辅因子进行催化，但相当数量的加氧酶和氧化酶既不包含也不需要任何辅因子。在无辅因子氧化酶中，尿酸氧化酶、粪卟啉原氧化酶和生成甲酰甘氨酸的酶具有机制和医学意义。生成甲酰甘氨酸的酶也是蛋白质工程的有前途的工具，因为它可以用于为蛋白质配备反应性醛基功能。PqqC 是细菌辅酶吡咯喹啉醌生物合成中的一种氧化酶，催化八电子环闭合氧化反应。在细菌加氧酶中，参与聚酮化合物修饰的醌形成单加氧酶、万古霉素和替考拉宁抗生素生物合成中发现的 DpgC 双加氧酶、来自 Renilla sp.的 luciferase 单加氧酶以及对 3-羟基-4(1H)-喹诺酮具有活性的细菌环裂解 2,4-二加氧酶已被鉴定为无辅因子酶。有趣的是，3-羟基-4(1H)-喹诺酮 2,4-二加氧酶和 Renilla luciferase 都使用 α/β-水解酶结构进行氧合反应。无辅因子氧化酶和加氧酶催化非常不同的反应，属于几个不同的蛋白质家族，反映了它们的多样性起源。然而，它们都可能共享其有机底物初始碱基催化激活和“底物辅助催化”的共同机制概念。
