Choline oxidase

 ( Ec 1.1.3 ) 

In enzymology, a choline oxidase () is an enzyme that catalysis the chemical reaction

choline + O₂ $\backslash rightleftharpoons$ betaine aldehyde + H₂O₂

Thus, the two substrates of this enzyme are choline and oxygen, whereas its two products are betaine aldehyde and H₂O₂.

This enzyme belongs to the family of , specifically those acting on the CH-OH group of donor with oxygen as acceptor. The systematic name of this enzyme class is choline:oxygen 1-oxidoreductase. This enzyme participates in glycine, serine, and threonine metabolism. It employs one cofactor, FAD.