ACT_SITE 63; /note="Schiff-base intermediate with substrate; via pyruvic acid"; /evidence="ECO:0000250"; ACT_SITE 68; /note="Proton acceptor; for processing activity"; /evidence="ECO:0000305|PubMed:15150268"; ACT_SITE 83; /note="Proton donor; for catalytic activity"; /evidence="ECO:0000305|PubMed:15150268"