Choline Dehydrogenase (CHDH)

CHDH catalyzes the four-electron oxidation of choline to glycine-betaine via a betaine-aldehyde intermediate. Such a reaction is of considerable interest for biotechnological applications in that transgenic plants engineered with bacterial glycine-betaine-synthesizing enzymes have been shown to have enhanced tolerance towards various environmental stresses, such as hypersalinity, freezing, and high temperatures. To date, choline dehydrogenase has been poorly characterized in its biochemical and kinetic properties, mainly because its purification has been hampered by instability of the enzyme in vitro. the kinetic data are consistent with the conclusion that H. elongata betA codes for a choline dehydrogenase that can also act as an oxidase when electron acceptors other than molecular oxygen are not available.