Phenylalanine hydroxylase

Definition

Phenylalanine hydroxylase is an enzyme responsible for converting the amino acid phenylalanine into tyrosine, which is a precursor for important neurotransmitters and hormones. This enzyme plays a crucial role in amino acid metabolism and its deficiency can lead to severe metabolic disorders, particularly phenylketonuria (PKU), highlighting its importance in human health.

5 Must Know Facts For Your Next Test

1. Phenylalanine hydroxylase is primarily found in the liver and is essential for the metabolism of phenylalanine.
2. Deficiency in this enzyme leads to PKU, which if left untreated, can result in cognitive impairment and other serious health issues.
3. Newborn screening for PKU is standard practice in many countries to ensure early diagnosis and management of the disorder.
4. Individuals with PKU must follow a strict low-phenylalanine diet to prevent toxic buildup and associated complications.
5. Tyrosine levels can become depleted in individuals with PKU due to the blockage in its production from phenylalanine.

Review Questions

• How does phenylalanine hydroxylase function within amino acid metabolism, and what are the consequences of its deficiency?
  • Phenylalanine hydroxylase functions by catalyzing the conversion of phenylalanine to tyrosine, which is a critical step in amino acid metabolism. When this enzyme is deficient, as seen in conditions like phenylketonuria (PKU), phenylalanine accumulates in the body. This accumulation can lead to serious neurological damage if not addressed through dietary management and treatment.
• What are the potential long-term effects on an individual's health if phenylketonuria caused by phenylalanine hydroxylase deficiency is not treated promptly?
  • If phenylketonuria (PKU) caused by phenylalanine hydroxylase deficiency is not treated promptly, it can lead to severe cognitive impairment, behavioral issues, and other neurological problems. The toxic buildup of phenylalanine affects brain development and function, making early detection and management critical to preventing irreversible damage.
• Evaluate the impact of newborn screening programs on the management of phenylketonuria related to phenylalanine hydroxylase.
  • Newborn screening programs have a significant impact on the management of phenylketonuria (PKU) related to phenylalanine hydroxylase by enabling early diagnosis and intervention. These programs allow for immediate dietary adjustments to limit phenylalanine intake, preventing the harmful effects associated with high levels of this amino acid. The success of such screening has led to improved outcomes for individuals with PKU, allowing them to lead healthier lives while managing their condition effectively.

Related terms

Phenylketonuria (PKU): A genetic disorder caused by the deficiency of phenylalanine hydroxylase, leading to the accumulation of phenylalanine in the body and resulting in neurological damage if untreated.

Tyrosine: An amino acid that is synthesized from phenylalanine and is involved in the production of neurotransmitters such as dopamine, norepinephrine, and epinephrine.

Amino Acid Metabolism: The biochemical process by which the body breaks down proteins into amino acids, which can then be used for energy, synthesis of new proteins, or converted into other compounds.