Choline → Betaine Aldehyde

For these enzymes, glucose oxidase catalyzes the reaction of β-D-glucose, water, and oxygen to produce hydrogen peroxide and gluconic acid. Galactose oxidase catalyzes the reaction of D-galactose and oxygen to produce hydrogen peroxide and D-galacto-hexodialdose. Urate oxidase catalyzes the reaction of uric acid, water, and oxygen to produce hydrogen peroxide, allantoin, and carbon dioxide. Choline oxidase catalyzes the reaction of choline and oxygen to produce hydrogen peroxide and betaine aldehyde. D-amino acid oxidase catalyzes the reaction of D-amino acids such as D-proline, D-methionine, D-isoleucine, D-alanine, D-valine, or D-phenylalanine with water and oxygen to produce hydrogen peroxide, ammonia, and the α-keto acid corresponding to the D-amino acid being oxidized. D-glutamate oxidase catalyzes the reaction of D-glutamic acid, water, and oxygen to produce hydrogen peroxide, ammonia, and 2-ketoglutarate. Glycine oxidase catalyzes the reaction of glycine, water, and oxygen to produce hydrogen peroxide, ammonia, and glyoxylic acid. Glycolic acid oxidase (also known as 2-hydroxyacid oxidase) catalyzes the reaction of glycolic acid and oxygen to produce 2-ketoacetic acid and hydrogen peroxide. L-sorbose oxidase catalyzes the reaction of L-sorbose and oxygen to produce 5-dehydro-D-fructose and hydrogen peroxide. Alcohol oxidase catalyzes the reaction of a lower primary alcohol or an unsaturated alcohol and oxygen to produce the corresponding aldehyde and hydrogen peroxide. Amine oxidase catalyzes the reaction of an amine, typically a primary amine, but also, in some cases, a secondary or tertiary amine, water, and oxygen to produce the corresponding aldehyde, ammonia, and hydrogen peroxide. In an illustrative reaction, glucose oxidase catalyzes the reaction of β-D-glucose, water, and oxygen during application to the outer ear to produce hydrogen peroxide and gluconic acid.