ACT_SITE 2; /note="Schiff-base intermediate with DNA"; ACT_SITE 3; /note="Proton donor"; /evidence="ECO:0000305"; ACT_SITE 53; /note="Proton donor; for beta-elimination activity"; /evidence="ECO:0000305"; ACT_SITE 253; /note="Proton donor; for delta-elimination activity"; /evidence="ECO:0000305"