Regional differences for the D-amino acid oxidase-catalysed oxidation of D-methionine in chicken small intestine.

1. Enzymic oxidation of D-[1-14C]methionine (D-met) to 2-keto-4-methylthiobutanoate (KMB) has been determined using 100,000 g supernatants prepared from chicken tissue homogenates. 2. The small intestinal mucosa contains substantial oxidative activity towards D-met, which represents about one-half and one-tenth the hepatic and renal activity, respectively. 3. KMB is poorly decarboxylated and rather transaminated to L-met. 4. The specific activity for D-met oxidation in the duodenal mucosa is 1.5- and 4.0-fold than in the jejunal and ileal mucosa, respectively. 5. The intestinal D-met-oxidizing activity is dramatically altered by the D-amino acid oxidase specific inhibitor benzoate.