fenilalaninhidroxiáz

Phenylalanine hydroxylase, often abbreviated as PAH, is an enzyme crucial for human metabolism. It is primarily found in the liver. Its main function is to catalyze the conversion of the essential amino acid phenylalanine into another amino acid, tyrosine. This conversion is a critical step in the metabolic pathway of phenylalanine.

The reaction involves the addition of a hydroxyl group to the side chain of phenylalanine. This process requires oxygen, a cofactor called tetrahydrobiopterin (BH4), and iron as a second cofactor. Without functional PAH, phenylalanine cannot be efficiently converted to tyrosine. This leads to a buildup of phenylalanine in the blood and other tissues.

A deficiency in PAH activity is the cause of phenylketonuria (PKU), a genetic disorder. In individuals with PKU, the inability to metabolize phenylalanine properly results in its accumulation to toxic levels. This can lead to severe intellectual disability, seizures, and other neurological problems if left untreated. Newborn screening programs are in place in many countries to detect PKU early, allowing for dietary management to prevent these devastating effects. This management typically involves restricting phenylalanine intake in the diet.