Tetrahydrobiopterin

Phenylketonuria (PKU) is a genetic disorder caused by a defect in the gene that helps create the enzyme phenylalanine hydroxylase. This enzyme helps to breakdown the amino acid phenylalanine; without this enzyme the levels of phenylketonuria (PKU) increases, this causes serious cognitive disabilities, hyperactivity, seizure, and abnormal small head (microcephaly) in infants, and small risk of brain damage.1 Phenylketonuria can affect pregnant women, babies, children and adults. Therefore, people who have the disease need to maintain a diet low in protein. Approximately 10,000 out of 15,000 babies are affected with phenylketonuria (PKU). This disease is more common in Irish, northern European, Turkish, or Native American people. Babies are test for this disease 48 hours after they are born to prevent false results. If the result is positive, these infants will need a strict diet. This diet consists of 40-60 mg/kg/d of dietary phenylalanine to maintain normal growth and development. Infants can have breast milk along with formula milk containing low phenylalanine. Some studies has proved that babies, who are feed with breast milk and formula, usually present a higher IQ, than those who only receive formula meal containing low phenylalanine.² Though, pediatrician can calculate the amount of formula milk to keep appropriate levels of phenylalanine in infants ² The treatment for Phenylketonuria (PKU) requires a low protein diet, and a medication regimen. Sapropterin…

Dietary intake and the recycling of amino acid stores are sources of phenylalanine. The first step in the catabolism is the irreversible conversion of phenylalanine to tyrosine by PAH. (1) Phenylalanine hydroxylase requires tetrahydrobiopterin as a co-factor. (1) PKU develops due to deficiency in or absence of phenylalanine hydroxylase. Deficiency in the PAH enzyme results in elevated phenylalanine and reduced levels of tyrosine. When the pathway to tyrosine is blocked, excess phenylalanine is…

Phenylketonuria (PKU) is a disorder that can be passed down from generation to generation. It is caused by a deficient hepatic phenylalanine hydroxylase (PAH), which is an enzyme in the liver that catalyzes the conversion of phenylalanine to tyrosine, using the coenzyme, tetrahydrobiopterin (BH4). One treatment for PKU would be to have a restricted diet because PKU does not allow for the process of phenylalanine, which is a protein found in many foods (Scala et al 2015). With the help of BH4,…

Phenylketonuria is an autosomal recessive disorder and a common metabolic cause of mental retardation. This inborn error of metabolism is characterized by a deficiency in phenylalanine (Phe) hydroxylase activity, due to mutations in the Phe hydroxylase (PAH) gene. Phenylalanine hydroxylase is responsible for converting Phe to Tyr and requires the cofactor tetrahydrobiopterin (BH4), molecular oxygen, and iron for its action (Blau et al., 2010). The reductant, BH4 is maintained in the reduced…

as one of the most influential neurotransmitters in the central nervous system, but also acts as a precursor of two other catecholamine groups: noradrenaline and adrenaline. This makes dopamine’s emergence in evolution an important step in the development of the central nervous system (Yamamoto, 2013). Dopamine’s emergence in evolution can be tracked and speculated on by looking at the emergence of specific genes that control the expression of genes that transform the compound from tyrosine to…

MECHANISM OF ACTIONS: MPA can induce the apoptosis of T-lymphocytes (activated only) which leads to elimination of cloned cells on antigenic stimulation. MPA depletes the guanosine nucleotides. It suppresses the glycosylation & also the expression of some of the adhesion molecules, which leads to decrease in the…