obsolete cis-4-(8-hydroxypyren-7-yl)-2-oxobut-3-enoate lyase activity (obsolete GO:0034815)
OBSOLETE. Catalysis of the reaction: cis-4-(8-hydroxypyren-7-yl)-2-oxobut-3-enoate = 10-oxabenzo(def)chrysen-9-one + formate + H+.