Defect in phenylketonuria: (A) Phenylanine hydroxylase, (B) Homogentisate oxidase, (C) Pyruvate hydroxylase, (D) Fumarylacetoacetate hydroxylase
Answer is A. In this condition phenylalanine can&;t be conveed to tyrosine, so phenylalanine accumulates and it&;s level in blood is elevated.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 236, fig 18.1