Monoamine oxidases (MAOs) use molecular dioxygen as oxidant to catalyze the oxidation of amines to imines. This type of enzyme can be employed for the synthesis of primary, secondary, and tertiary amines by an appropriate deracemization protocol. Consequently, MAOs are an attractive class of enzymes in biocatalysis. However, they also have limitations in enzyme-catalyzed processes due to the often-observed narrow substrate scope, low activity, or poor/wrong stereoselectivity. Therefore, directed evolution was introduced to eliminate these obstacles, which is the subject of this review. The main focus is on recent efforts concerning the directed evolution of four MAOs: monoamine oxidase (MAO-N), cyclohexylamine oxidase (CHAO), D-amino acid oxidase (pkDAO), and 6-hydroxy-D-nicotine oxidase (6-HDNO).

中文翻译：

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立体选择性单胺氧化酶定向进化的最新进展

单胺氧化酶（MAO）使用分子双氧作为氧化剂来催化胺氧化为亚胺。可以通过适当的脱硝方案将这种类型的酶用于伯，仲和叔胺的合成。因此，MAO在生物催化中是一类有吸引力的酶。然而，由于经常观察到的底物范围狭窄，活性低或立体选择性差/错误，它们在酶催化过程中也有局限性。因此，引入定向进化来消除这些障碍，这是本综述的主题。主要关注于有关四种MAO定向进化的最新研究成果：单胺氧化酶（MAO-N），环己胺氧化酶（CHAO），D-氨基酸氧化酶（pkDAO）和6-羟基-D-尼古丁氧化酶（6-HDNO）。