L-amino acid oxidase (LAAO)

L-amino acid oxidase (LAAO) is a flavin adenine dinucleotide (FAD)-dependent enzyme that catalyzes the oxidative deamination of L-amino acids into their corresponding alpha-keto acids, releasing ammonia and hydrogen peroxide as byproducts [1, 10]. It is widely distributed across various taxa, including bacteria, fungi, and animals, with particularly high concentrations found in snake venoms [2, 10]. In humans, the most well-characterized LAAO is Interleukin-4-induced gene 1 (IL4I1), which plays a critical role in immunomodulation by inhibiting T-cell proliferation and promoting the differentiation of regulatory T-cells [6, 11]. In the context of disease, LAAOs are significant both as therapeutic targets and potential drug candidates; for instance, IL4I1 is targeted in cancer immunotherapy to overcome the immunosuppressive tumor microenvironment, while snake venom LAAOs (svLAAOs) are being explored for their potent antimicrobial and pro-apoptotic anticancer properties [4, 7, 9]. The therapeutic application of LAAOs primarily leverages the localized production of hydrogen peroxide to induce oxidative stress-mediated cell death in pathogens or malignant cells [5, 15]. However, challenges such as non-specific cytotoxicity, potential for systemic toxicity, and the induction of edema or hemolysis must be addressed for clinical translation [4, 10].

Other names

L-amino-acid:oxygen oxidoreductase (deaminating)Ophio-amino-acid oxidaseInterleukin-4-induced gene 1IL4I1Phenylalanine oxidase

Catalyzes the oxidative deamination of L-amino acids to produce alpha-keto acids, ammonia, and hydrogen peroxide, leading to oxidative stress and apoptosis in target cells or immunosuppression in the tumor microenvironment.