4.1.3.3	aceneuramate = N-acetyl-D-mannosamine + pyruvate	mechanism	33315, 650651, 651103, 652833, 652991	
4.1.3.3	aceneuramate = N-acetyl-D-mannosamine + pyruvate	the enzyme catalyzes a Bi-Uni ordered condensation reaction in which pyruvate binds first to the enzyme to form a catalytically important Schiff base. Tyr137 acts as the proton donor to the aldehyde oxygen of ManNAc during the reaction, the activation barrier is dominated by carbon-carbon bond formation, and proton transfer from Tyr137 is required to obtain a stable Neu5Ac-Lys165 Schiff base complex. A triad of residues, Tyr137, Ser47, and Tyr110 from a neighboring subunit, are required to correctly position Tyr137 for its function	726551