Probing the active site of L-aspartate oxidase by site-directed mutagenesis : role of basic residues in fumarate reduction

Site-directed mutagenesis of L-aspartate oxidase, which behaves as a fumarate reductase in anaerobic conditions, reveals that R386, H244, and H31 are involved in the fumarate binding and catalysis while R290 is involved only in the catalysis. Data show that L-aspartate active site is similar to that of fumarate reductase.