Recent progress in directed evolution of stereoselective monoamine oxidases

Abstract

Abstract 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).

Keywords

• Monoamine oxidase
• Directed evolution
• Stereoselectivity
• Chiral amine