Purity >98%. Bacterial DNA gyrase is a heterodimeric type II topoisomerase that negatively supercoils circular double-stranded DNA. Oxolinic acid is a quinolone antibiotic that inhibits bacterial DNA gyrase, but not eukaryotic topoisomerases, reversibly binding gyrase subunit A in gyrase-DNA complexes, blocking supercoiling activity and inhibiting DNA synthesis at 0.5-5 μg/ml. Oxolinic acid also blocks neuronal uptake of dopamine in mammals (IC50 = 4.3 μM), leading to an increase in locomotor activity.