Benzo(a)pyrenedione/benzol(a)pyrenediol oxidation--reduction couples and the generation of reactive reduced molecular oxygen. [Clostridium kluyveri, bacteriophage T7]

Journal Article · Tue Apr 05 00:00:00 EST 1977 · Biochemistry; (United States)

OSTI ID:7259954

Lorentzen, R J; Ts'o, P O.P.

The ability of the isomeric quinone metabolites of benzo(a) pyrene, benzo(a)pyrene-6,12-dione, benzo(a)pyrene-1,6-dione, and benzo(a)pyrene-3,6-dione to undergo reversible, univalent oxidation--reduction cycles involving the corresponding benzo(a)pyrenediols and intermediate semiquinone radicals has been characterized. Under anaerobic conditions, all three benzo(a)pyrenediones are easily reduced to benzo(a)pyrenediols, even by mild biological agents such as NAD(P)H, cysteamine, and glutathione. The benzo(a)pyrenediols, in turn, are very rapidly autoxidized to the benzo(a)pyrenediones when exposed to air. Substantial amounts of hydrogen peroxide are produced during these autoxidations, and other reactive reduced oxygen species, such as the superoxide and hydroxyl radicals, are probably formed transiently as well. The benzo(a)pyrenediol--benzo(a)pyrenedione interconversions proceed by one-electron steps; the corresponding semiquinone radicals can be monitored by electron spin resonance spectroscopy as intermediates during these reactions carried out at high pH. Benzo(a)pyrenediones induce DNA strand scission when incubated with bacteriophage T7 DNA. This damage is modified by conditions which indicate that reduced oxygen species propagate the free-radical reactions responsible for the strand scission. Benzo(a)pyrenediones are electron-acceptor substrates for NADH dehydrogenase from Clostridium kluyveri. Catalytic amounts of these benzo(a)pyrene metabolites, together with this respiratory enzyme, function as cyclic oxidation--reduction couples which link NADH and molecular oxygen in the continuous production of hydrogen peroxide.

• Research Organization: Johns Hopkins Univ., Baltimore
• DOE Contract Number: E(11-1)-3280
• OSTI ID: 7259954
• Journal Information: Biochemistry; (United States), Vol. 16:7; Conference: 67. annual meeting of the American Association for Cancer Research, Toronto, Ont., 1976
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
BENZOPYRENE
METABOLISM
DEHYDROGENASES
CHEMICAL REACTIONS
DNA
STRAND BREAKS
NUCLEIC ACIDS
QUINONES
BACTERIOPHAGES
CLOSTRIDIUM
ELECTRON SPIN RESONANCE
OXIDATION
OXYGEN
RADICALS
REDUCTION
SPECTROSCOPY
AROMATICS
BACTERIA
CONDENSED AROMATICS
CRYOGENIC FLUIDS
ELEMENTS
ENZYMES
FLUIDS
HYDROCARBONS
MAGNETIC RESONANCE
MICROORGANISMS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDOREDUCTASES
PARASITES
RESONANCE
VIRUSES
550200* - Biochemistry
550500 - Metabolism