An enzyme that catalyzes the reduction of 6,7-dihydropteridine to 5,6,7,8-tetrahydropteridine in the presence of NADP+. Defects in the enzyme are a cause of PHENYLKETONURIA II. Formerly listed as EC 1.6.99.7.

A group of oxidoreductases that act on NADH or NADPH. In general, enzymes using NADH or NADPH to reduce a substrate are classified according to the reverse reaction, in which NAD+ or NADP+ is formally regarded as an acceptor. This subclass includes only those enzymes in which some other redox carrier is the acceptor. (Enzyme Nomenclature, 1992, p100) EC 1.6.

Compounds based on pyrazino[2,3-d]pyrimidine which is a pyrimidine fused to a pyrazine, containing four NITROGEN atoms.

A leukomaine (animal alkaloid) formed in brain and liver from dopamine and L-dopa; it may be implicated in psychiatric problems.

A group of autosomal recessive disorders marked by a deficiency of the hepatic enzyme PHENYLALANINE HYDROXYLASE or less frequently by reduced activity of DIHYDROPTERIDINE REDUCTASE (i.e., atypical phenylketonuria). Classical phenylketonuria is caused by a severe deficiency of phenylalanine hydroxylase and presents in infancy with developmental delay; SEIZURES; skin HYPOPIGMENTATION; ECZEMA; and demyelination in the central nervous system. (From Adams et al., Principles of Neurology, 6th ed, p952).

Tetrahydroisoquinolinol alkaloids in both dextro and levo forms, originally found in SALSOLA plants.

A natural product that has been considered as a growth factor for some insects.

Compounds based on 2-amino-4-hydroxypteridine.

A dye used as a reagent in the determination of vitamin C.

An enzyme of the oxidoreductase class that catalyzes the formation of L-TYROSINE, dihydrobiopterin, and water from L-PHENYLALANINE, tetrahydrobiopterin, and oxygen. Deficiency of this enzyme may cause PHENYLKETONURIAS and PHENYLKETONURIA, MATERNAL. EC 1.14.16.1.

Pigment obtained by the oxidation of epinephrine.

A coenzyme composed of ribosylnicotinamide 5'-diphosphate coupled to adenosine 5'-phosphate by pyrophosphate linkage. It is found widely in nature and is involved in numerous enzymatic reactions in which it serves as an electron carrier by being alternately oxidized (NAD+) and reduced (NADH). (Dorland, 27th ed)

An essential aromatic amino acid that is a precursor of MELANIN; DOPAMINE; noradrenalin (NOREPINEPHRINE), and THYROXINE.

A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.