Carnitine biosynthesis. Purification of 4-N'-trimethylaminobutyraldehyde dehydrogenase from beef liver.

4-N-Trimethylaminobutyrate is formed during carnitine biosynthesis by the oxidation of 4-N-trimethylaminobutyraldehyde. The aldehyde dehydrogenase which catalyzes this reaction has been isolated from bovine liver. This enzyme was purified to homogeneity, as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis, using two affinity type columns. Blue dextran and 5'-AMP covalently linked to a Sepharose matrix were used to bind this NAD+-requiring enzyme. Two other aldehyde dehydrogenases with broader specificities were also purified to homogeneity using the same affinity columns. The three enzymes appear to be distinct as they are different with respect to subcellular locations, substrate specificity, behavior on the affinity columns, disulfiram inhibition, and esterase activity. The enzyme with preference for trimethylaminobutyraldehyde as substrate probably functions in carnitine biosynthesis.