Bioresour Technol. 2026 Jun 23:135229. doi: 10.1016/j.biortech.2026.135229. Online ahead of print.
ABSTRACT
Amino acid oxidases (AAOs: EC 1.4.3.X, D- and l-forms) have attracted significant interest as promising biocatalysts for the synthesis of high-value chiral compounds, including natural and non-natural amino acids. These FAD-dependent enzymes catalyze the oxidative deamination of amino acids to corresponding imino acids (which subsequently degrade to keto acids), producing H2O2 and ammonia as byproducts. Owing to their high catalytic performance, excellent enantioselectivity, and broad substrate scope, AAOs have recently attracted considerable attention in the pharmaceutical and agrochemical industries. This review provides a comprehensive analysis of catalytic mechanisms and activity assays of both D- and l-forms of AAOs. Special emphasis is placed on recent advances in protein engineering strategies, including directed evolution, rational/semi-rational and AI-guided approaches that have remarkably enhanced enzyme properties such as activity, stability, and substrate scope. Furthermore, the review highlights the expanding synthetic applications of AAOs, including chemoenzymatic cascade reactions, multi-enzyme cascade deracemization and kinetic resolution, demonstrating their utility in the efficient production of pharmaceutically and industrially relevant amino acids and their derivatives. By addressing current challenges and highlighting emerging strategies, this review offers critical insights to advance the application of AAOs in modern biocatalysis and synthetic biology.
PMID:42336113 | DOI:10.1016/j.biortech.2026.135229