Biochemistry All India exam 7a79954f A patient complains of knee pain Routine investigations are unremarkable and still the patient is unsatisfied Urine turns black on standing what is the enzyme involved A Homogentisate Oxidase B Xanthine oxidase C Phenylalanine hydroxylase D Dihydroorlate Dehydrogenase High-Yield Explanation REF : LIPPINCOTT 6TH ED