Forms part of the nicotinate-fermentation catabolism pathway in?Eubacterium barkeri. Other enzymes involved in this pathway are EC?1.17.5.1?(nicotinate dehydrogenase), 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) and EC?4.2.1.85?(dimethylmaleate hydratase).