Benzopyrene Hydroxylase: A drug-metabolizing, cytochrome P-448 (P-450) enzyme which catalyzes the hydroxylation of benzopyrene to 3-hydroxybenzopyrene in the presence of reduced flavoprotein and molecular oxygen. Also acts on certain anthracene derivatives. An aspect of EC 126.96.36.199.Benzopyrenes: A class of chemicals that contain an anthracene ring with a naphthalene ring attached to it.Nikethamide: A central nervous system stimulant. It was formerly used in the treatment of barbiturate overdose but is now considered to be of no value for such purposes and may be dangerous. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1229)Phenylalanine Hydroxylase: 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 188.8.131.52.Steroid 21-Hydroxylase: An adrenal microsomal cytochrome P450 enzyme that catalyzes the 21-hydroxylation of steroids in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP21 gene, converts progesterones to precursors of adrenal steroid hormones (CORTICOSTERONE; HYDROCORTISONE). Defects in CYP21 cause congenital adrenal hyperplasia (ADRENAL HYPERPLASIA, CONGENITAL).Tryptophan Hydroxylase: An enzyme that catalyzes the hydroxylation of TRYPTOPHAN to 5-HYDROXYTRYPTOPHAN in the presence of NADPH and molecular oxygen. It is important in the biosynthesis of SEROTONIN.Tyrosine 3-Monooxygenase: An enzyme that catalyzes the conversion of L-tyrosine, tetrahydrobiopterin, and oxygen to 3,4-dihydroxy-L-phenylalanine, dihydrobiopterin, and water. EC 184.108.40.206.Mixed Function Oxygenases: Widely distributed enzymes that carry out oxidation-reduction reactions in which one atom of the oxygen molecule is incorporated into the organic substrate; the other oxygen atom is reduced and combined with hydrogen ions to form water. They are also known as monooxygenases or hydroxylases. These reactions require two substrates as reductants for each of the two oxygen atoms. There are different classes of monooxygenases depending on the type of hydrogen-providing cosubstrate (COENZYMES) required in the mixed-function oxidation.Procollagen-Proline Dioxygenase: A mixed-function oxygenase that catalyzes the hydroxylation of a prolyl-glycyl containing peptide, usually in PROTOCOLLAGEN, to a hydroxyprolylglycyl-containing-peptide. The enzyme utilizes molecular OXYGEN with a concomitant oxidative decarboxylation of 2-oxoglutarate to SUCCINATE. The enzyme occurs as a tetramer of two alpha and two beta subunits. The beta subunit of procollagen-proline dioxygenase is identical to the enzyme PROTEIN DISULFIDE-ISOMERASES.