Metabolic Pathway for Phenylalanine and Tyrosine ( For MCQ Practice click here ) Conversion of Phenylalanine to Tyrosine - Phenylalanine hydroxylase (PAH) converts phenylalanine to tyrosine - PAH is encoded by the PAH gene located in Chromosome 12 and consist of 13 exons - Tetrameters with each monomer consisting of the catalytic site, regulator site, and subunit binding domain - Phenylalanine hydroxylase is tetrahydrobiopterin (BH4) requiring enzyme - Dihydrobioteridine reductase catalyzes the conversion of dihydrobiopteridine to tetrahydrobiopterin - Deficiency of enzyme caused phenylketonuria Figure- Overview of Phenylalanine and Tyrosine Metabolism Transamination of Tyrosine - Tyrosine aminotransferase catalyzes the conversion to tyrosine to p-hydroxyphenylpyruvate - Tyrosine aminotransferase is a Pyridoxal-5-phosphate requiring enzyme - In the process, alpha-ketoglutarate is converted into glutama...