D-amino-acid oxidase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: a D-amino acid + H2O + O2 = a 2-oxo acid + NH3 + hydrogen peroxide. [EC:1.4.3.3]

D-amino-acid oxidase activity is a catalytic function that specifically oxidizes D-amino acids, which are stereoisomers of the naturally occurring L-amino acids. This enzymatic activity involves the removal of two hydrogen atoms from the α-carbon of a D-amino acid, resulting in the formation of an α-keto acid and ammonia. The reaction requires molecular oxygen as the oxidant, which is reduced to hydrogen peroxide as a byproduct.

D-amino-acid oxidases belong to the flavin-containing oxidoreductase family, and their active site contains a flavin adenine dinucleotide (FAD) cofactor. The catalytic cycle of D-amino-acid oxidase begins with the binding of a D-amino acid substrate to the enzyme, followed by the reduction of the FAD cofactor to FADH2. This reduction step involves the transfer of two electrons from the substrate to FAD, which is accompanied by the release of ammonia. The reduced FAD cofactor then reacts with molecular oxygen, regenerating the oxidized FAD and generating hydrogen peroxide. The α-keto acid product is released from the enzyme, and the cycle is ready to begin anew.

D-amino-acid oxidase activity plays a crucial role in various biological processes, including:

* **Amino acid metabolism:** D-amino-acid oxidases catalyze the breakdown of D-amino acids, which are not typically found in proteins but can be produced by various metabolic pathways or through bacterial contamination.
* **Neurotransmission:** Some D-amino acids, such as D-serine, act as neuromodulators, and their levels are regulated by D-amino-acid oxidase activity.
* **Immune response:** D-amino-acid oxidase activity is involved in the production of reactive oxygen species, which contribute to immune responses.

The specific D-amino acids that can be oxidized by D-amino-acid oxidases vary depending on the enzyme. Some D-amino-acid oxidases exhibit broad substrate specificity, while others are more selective. For example, the enzyme D-amino acid oxidase (DAO) found in mammals primarily oxidizes D-serine and D-alanine.'
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Proteins (1)

Compounds (33)