Purification and characterization of a benzene hydroxylase: A cytochrome P-450 from rat liver mitochondria
Thesis/Dissertation
·
OSTI ID:6714054
This laboratory previously demonstrated that incubation of ({sup 14}C)benzene with isolated mitochondria resulted in the formation of mtDNA adducts. Since benzene is incapable of spontaneously covalently binding to nuclei acids, it was hypothesized that enzyme(s) present in the organelle metabolized benzene to reactive derivatives. We have purified, to electrophoretic homogeneity, a 52 kDa cytochrome P-450 from liver mitoplasts which metabolizes benzene to phenol. The enzyme has a K{sub M} for benzene of 0.012 mM, and a V{sub MAX} of 22.6 nmol phenol/nmol P-450/10 min, and requires NADPH, adrenodoxin, and adrenodoxin reductase for activity. Activity also can be reconstituted with microsomal cytochrome P-450 reductase. Benzene hydroxylase activity could be inhibited by carbon monoxide and SKF-525A, and by specific inhibitors of microsomal benzene metabolism. The purified enzyme oxidized phenol, forming catechol; aminopyrine N-demethylase activity was also demonstrated. These data confirm that a cytochrome P-450 of mitochondrial origin is involved in benzene metabolism, and indicate a role for the mitochondrion in xenobiotic activation.
- Research Organization:
- Thomas Jefferson Univ., Philadelphia, PA (USA)
- OSTI ID:
- 6714054
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
550201 -- Biochemistry-- Tracer Techniques
560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ADDUCTS
AROMATICS
BENZENE
BIOLOGICAL FUNCTIONS
CARBON 14 COMPOUNDS
CELL CONSTITUENTS
DNA ADDUCTS
ELECTROPHORESIS
ENZYME ACTIVITY
ENZYMES
FUNCTIONS
HYDROCARBONS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
METABOLISM
MICROSOMES
MITOCHONDRIA
MIXED-FUNCTION OXIDASES
ORGANIC COMPOUNDS
ORGANOIDS
OXIDOREDUCTASES
OXYGENASES
PHENOL
PHENOLS
RIBOSOMES
TRACER TECHNIQUES
560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ADDUCTS
AROMATICS
BENZENE
BIOLOGICAL FUNCTIONS
CARBON 14 COMPOUNDS
CELL CONSTITUENTS
DNA ADDUCTS
ELECTROPHORESIS
ENZYME ACTIVITY
ENZYMES
FUNCTIONS
HYDROCARBONS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
METABOLISM
MICROSOMES
MITOCHONDRIA
MIXED-FUNCTION OXIDASES
ORGANIC COMPOUNDS
ORGANOIDS
OXIDOREDUCTASES
OXYGENASES
PHENOL
PHENOLS
RIBOSOMES
TRACER TECHNIQUES