In enzymology, betaine-aldehyde dehydrogenase () is an enzyme that catalyzes the chemical reaction
The three substrates of this enzyme are glycine betaine aldehyde, oxidised nicotinamide adenine dinucleotide (NAD<sup>+</sup>), and water. Its products are trimethylglycine, reduced NADH, and a proton.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the aldehyde or oxo group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is betaine-aldehyde:NAD+ oxidoreductase. Other names in common use include betaine aldehyde oxidase, BADH, betaine aldehyde dehydrogenase, and BetB. This enzyme participates in glycine, serine and threonine metabolism.
, 4 structures have been solved for this class of enzymes, with PDB accession codes , , , and .