Previous studies have shown that the presence of one P450 enzyme can affect the function of another. The goal of the present study was to determine if P450 enzymes are capable of forming homomeric complexes that affect P450 function. To address this problem, the catalytic activities of several P450s were examined in reconstituted systems containing NADPH-POR (cytochrome P450 reductase) and a si...

Alternative Names Adrenal Hyperplasia III 21-@Hydroxylase Deficiency CYP21 Deficiency Congenital Adrenal Hyperplasia 1 CAH1 Cytochrome P450, Subfamily XXIA, Polypeptide 2 CYP21A2 Cytochrome P450, Subfamily XXI CYP21 Steroid Cytochrome P450 21-Hydroxylase P450c21 21-@Hydroxylase B, Included CYP21B CA21H Cytochrome P450, Subfamily XXIA, Polypeptide 1 Pseudogene CYP21A1P CYP21P CYP21A Hyperandroge...

Numerous cytochrome P450 inhibitors have been described as effective modulators of cytochrome P450 isoforms activity in vitro. Their inhibitory efficiency may be considerably modified after in vivo application. The aim of this study was to examine the effect of oral administration of diallyl sulfide--a cytochrome P450 2E1 inhibitor and cimetidine--a cytochrome P450 2C6 and 2C11 inhibitor on rat...

Studies of tumor cell lines expressing individual cytochrome P450 genes are essential for evaluation of the utility of P450 prodrug activation-based cancer gene therapy (1). P450-expressing tumor cells may also be useful to identify novel P450 gene /prodrug combinations (see Chapter 5). The evaluation of candidate P450 genes for use in prodrug activation gene therapy is greatly facilitated by t...

Cytochromes P450 are a superfamily of heme proteins involved in oxidative metabolism of endogenous chemicals such as steroid hormones and human-made xenobiotics including drugs and environmental pollutants. Hundreds of P450s have been demonstrated by cDNA and gene cloning in animals, plants, fungi, and bacteria. Most of the mammalian xenobiotic-metabolizing P450s, found within the eight subfami...

The anticonvulsant phenytoin (5,5-diphenylhydantoin) provokes a skin rash in 5 to 10% of patients, which heralds the start of an idiosyncratic reaction that may result from covalent modification of normal self proteins by reactive drug metabolites. Phenytoin is metabolized by cytochrome P450 (P450) enzymes primarily to 5-(p-hydroxyphenyl-),5-phenylhydantoin (HPPH), which may be further metaboli...

Beraprost sodium (BPS), a chemically stable and orally active prostacyclin analogue used for the treatment of chronic occlusive disease and primary pulmonary hypertension, was investigated in terms of its drug-drug interaction mediated by cytochrome P450. In a metabolic enzyme characterization study using P450-expressing insect cell microsomes, beraprost (BP) was slightly metabolized in the pre...

Common marmosets (Callithrix jacchus) are attracting attention as animal models in preclinical studies for drug development. However, cytochrome P450s (P450s), major drug-metabolizing enzymes, have not been fully identified and characterized in marmosets. In this study, based on the four novel P450 4F genes found on the marmoset genome, we successfully isolated P450 4F2, 4F3B, 4F11, and 4F12 cD...

Benzo[a]pyrene (BaP) is a human carcinogen that covalently binds to DNA after activation by cytochrome P450 (P450). Here, we investigated whether NADH:cytochrome b5 reductase (CBR) in the presence of cytochrome b5 can act as sole electron donor to human P450 1A1 during BaP oxidation and replace the canonical NADPH:cytochrome P450 reductase (POR) system. We also studied the efficiencies of the c...