1.1.1.254 (R)-3-hydroxy-4-trimethylaminobutyrate + NAD+ - 1.1.1.254 (S)-3-hydroxy-4-trimethylaminobutyrate + NAD+ - 1.1.1.254 (S)-3-hydroxy-4-trimethylaminobutyrate + NAD+ D-carnitine dehydrogenase 1.1.1.254 (S)-carnitine + NAD+ substrate is derived as a waste product from chemical production procedures of L(-)-carnitine 1.1.1.254 additional information initial step of D(+)-carnitine degradation 1.1.1.254 additional information it is expected that D-carnitine can be converted into L-carnitine by coupling reactions of D-carnitine dehydrogenase and L-carnitine dehydrogenase 1.1.1.254 additional information enzyme is induced during growth on D-carnitine