. "Catalysis of the reaction: threo-3-methyl-L-aspartate = mesaconate + NH(4)(+)." . . "methylaspartate ammonia-lyase activity" . "3-methylaspartase activity" . "beta-methylaspartase activity" . "L-threo-3-methylaspartate ammonia-lyase (mesaconate-forming)" . "L-threo-3-methylaspartate ammonia-lyase activity" . . .