Biochem/physiol Actions
Choline oxidase from Arthrobacter sp. is a flavoprotein, which is a member of the GMC-oxidoreductase family. The enzyme catalyzes the four-electron-oxidation of choline to glycine betaine via the intermediate betaine aldehyde, in two sequential FAD-dependent reaction steps. The enzyme is useful for enzymatic determination of phosphatidylcholine by coupling with phospholipase D[1] or determination of sphingomyelin by coupling with sphingomyelinase[2] and for cholinesterase activity assays.[3]
Preparation Note
It is recommended to reconstitute choline oxidase in phosphate buffer at pH 7.5 supplemented with 10mM EDTA. Reconstituted material can be stored at 2-8 °C for at least 2 weeks.
Unit Definition
One unit will form 1 μmole of H2O2 with oxidation of 1 μmole of choline to betaine aldehyde per min at pH 8.0 at 37 °C. Note: During the conversion of choline to betaine by choline oxidase, 2 μmoles of H2O2 are produced for every μmole of choline.