Methylaspartate ammonia-lyase (MAL)

Methylaspartate ammonia-lyase is an enzyme (EC 4.3.1.2) predominantly found in certain bacteria (e.g., Citrobacter, Clostridium), where it plays a key role in the catabolism of glutamate via the methylaspartate pathway and in nitrogen metabolism. The enzyme catalyzes the reversible deamination of L-threo-3-methylaspartate to produce mesaconate and ammonia, employing magnesium or cobamide as cofactors. Structurally, it is a homodimer with a TIM barrel domain and belongs to the enolase superfamily. MAL’s catalytic mechanism involves abstraction of a proton alpha to the carboxyl group of methylaspartate, followed by elimination of ammonia, a process important for bacterial fermentation in anaerobic conditions. There are no clinically relevant drugs, safety concerns, or disease roles associated with this enzyme in humans, but it is a well-characterized tool in microbial biochemistry and metabolic engineering[1][2][3][4][5][7][10].

Other names

Beta-methylaspartase3-methylaspartaseL-threo-3-methylaspartate ammonia-lyase

Catalyzes the reversible alpha,beta-elimination of ammonia from L-threo-3-methylaspartic acid to form mesaconate Requires magnesium (Mg2+) or, in some forms, cobamide as cofactors[1][2][3] Utilizes a base-catalyzed abstraction of a proton followed by elimination of ammonia, forming an enolate intermediate[5][7]