The natural cofactor of phenylalanine hydroxylase (PAH), tetrahydrobiopterin (BH4), regulates the enzyme activity as well as being essential in catalysis. BH4-responsive PAH deficiency is a variant of hyperphenylalaninemia or phenylketonuria (PKU) caused by mutations in the human PAH gene that respond to oral BH4 loading by stimulating enzyme activity and therefore lowering serum phenylalanine....

Pigmentation during insect development is a primal adaptive requirement. In the silkworm, melanin is the primary component of larval pigments. The rate limiting substrate in melanin synthesis is tyrosine, which is converted from phenylalanine by the rate-limiting enzyme phenylalanine hydroxylase (PAH). While the role of tyrosine, derived from phenylalanine, in the synthesis of fiber proteins ha...

Hyperphenylalaninemia, a disorder of phenylalanine catabolism, is caused primarily by a deficiency of the hepatic apoenzyme phenylalanine-4-hydroxylase (PAH) or by one of the enzymes involved in its cofactor bio-synthesis (GTP cyclohydrolase I, GTPCH; and 6-pyruvoyl-tetrahydropterin synthase, PTPS) or its regeneration (dihydropteridine reductase, DHPR; and pterin carbinolamine-4a-dehydratase, P...

Analytical ultracentrifugation has been used to analyze the oligomeric structure of the isolated regulatory domain of phenylalanine hydroxylase. The protein exhibits a monomer-dimer equilibrium with a dissociation constant of ~46 μM; this value is unaffected by the removal of the 24 N-terminal residues or by phosphorylation of Ser16. In contrast, phenylalanine binding (Kd = 8 μM) stabilizes the...

Phenylketonuria (PKU) is caused by hepatic phenylalanine hydroxylase (PAH) deficiency and is associated with systemic accumulation of phenylalanine (Phe). Previously we demonstrated correction of murine PKU after intravenous injection of a recombinant type 2 adeno-associated viral vector pseudotyped with type 8 capsid (rAAV2/8), which successfully directed hepatic transduction and Pah gene expr...

Tetrahydrobiopterin (BH4)-responsive phenylalanine hydroxylase (PAH) deficiency is a recently recognized variant of phenylketonuria, with a probable multifactorial molecular basis. In this study we have investigated the effect of BH4 on PAH gene expression in human hepatoma. Our results show that increased BH4 levels result in an enhancement of PAH activity and PAH protein, due to longer turnov...

phenylketonuria (pku) is an inborn error of amino acid metabolism with an autosomal recessive inheritance caused in most cases by mutations in the phenylalanine hydroxylase (pah) gene. pku has wide allelic heterogeneity. here we report a novel heterozygous substitution (c.1223g>t (p.arg408leu)) in the pah gene in an iranian pku family. the patient was 19-yr-old female with diagnosis of moderate...

We have found that the induction of phenylalanine hydroxylase by hydrocortisone and serum in confluent cultures of H4-II-E-C3 rat hepatoma cells is accompanied by an increase in polysomal mRNA specific for phenylalanine hydroxylase, as measured by translation in a cell-free protein-synthesizing system. Thus, the induction is mediated largely, if not entirely, by a pretranslational mechanism, po...

Phenylketonuria (PKU) is one of the most common metabolic inborn diseases caused by mutations in the phenylalanine hydroxylase (PAH) gene. This gene is linked to a variable number of tandem repeats (VNTR) region which is a polymorphic marker that facilitates the implementation of prenatal diagnosis and carrier screening. In this study, VNTR with 13 repeats that has not been reported previously ...

Background and Objective: Phenylketonuria (PKU) is a metabolic disorder that is caused by mutations in the phenylalanine hydroxylase (PAH) gene. The multiplicity of mutations in the PAH gene of PKU leads to the cases, in which the pathogenic mutation cannot be detected. In these cases, the variable number of tandem repeat (VNTR), which is the polymorphic marker associated with the PAH gene, is ...