ACT_SITE 21; /evidence="ECO:0000250"; ACT_SITE 24; /evidence="ECO:0000250"; ACT_SITE 85; /note="Schiff-base intermediate with substrate; via pyruvic acid"; /evidence="ECO:0000250"; ACT_SITE 99; /note="Proton donor; for catalytic activity"; /evidence="ECO:0000250"; ACT_SITE 275; /note="Proton acceptor; for processing activity"; /evidence="ECO:0000250"; ACT_SITE 288; /note="Proton acceptor; for processing activity"; /evidence="ECO:0000250"