An Alcaptonuric Lacks the Enzyme That Oxidizes Which Metabolite

Question

An alcaptonuric lacks the enzyme that oxidizes which metabolite?
A)phenylalanine
B)tyrosine
C)homogentisic acid
D)asparagine
E)pantothenic acid

Accepted Answer

Alcaptonuria is caused by a deficiency in the enzyme homogentisate 1,2-dioxygenase, which catalyzes the oxidation of the amino acid tyrosine to produce homogentisic acid (HGA). Therefore, an alcaptonuric individual cannot oxidize HGA, leading to its accumulation and excretion in the urine.