A flavoprotein containing non-heme iron. The enzyme is capable of acting on a variety of nicotinate analogues to varying degrees, including pyrazine-2-carboxylate, pyrazine 2,3-dicarboxylate, trigonelline and 6-methylnicotinate. The enzyme from Clostridium barkeri also possesses a catalytically essential, labile selenium that can be removed by reaction with cyanide. Requires a cobamide coenzyme. Forms part of the nicotinate-fermentation catabolism pathway in Eubacterium barkeri. Other enzymes involved in this pathway are EC 1.3.7.1 (6-hydroxynicotinate reductase), EC 3.5.2.18 (enamidase), EC 1.1.1.291 (2-hydroxymethylglutarate dehydrogenase), EC 5.4.99.4 (2-methyleneglutarate mutase), EC 5.3.3.6 (methylitaconate ¦¤-isomerase), EC 4.2.1.85 (dimethylmaleate hydratase) and EC 4.1.3.32 (2,3-dimethylmalate lyase).
