obsolete 5,6-dihydroxy-3-methyl-2-oxo-1,2-dihydroquinoline dioxygenase activity (obsolete GO:0018558)
OBSOLETE. Catalysis of the reaction: 5,6-dihydroxy-3-methyl-2-oxo-1,2-dihydroquinoline + O2 = 3-methyl-5-hydroxy-6-(3-carboxy-3-oxopropenyl)-1H-2-pyridon.