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Kinetics of the inhibition of styrene oxide and benzo(a)pyrene-4,5-oxide hydration in rat liver microsomes by cadmium. 1980

M G Parkki, and A Aitio, and J R Bend

The kinetics of the inhibition by cadmium of styrene oxide and benzo(a)pyrene-4,5-oxide hydration were studied in a microsomal preparation from rat liver. Cadmium inhibited the hydration of styrene oxide in an apparently noncompetitive manner, whereas the inhibition of benzo(a)pyrene-4,5-oxide hydration showed a competitive mechanism. Styrene oxide inhibited the hydration of benzo(a)pyrene-4,5-oxide competitively and cyclohexene oxide inhibited the hydration of both styrene oxide and benzo(a)pyrene-4,5-oxide competitively. The present data suggest that cadmium is bound near the active centre of the enzyme. Occupation of this site by cadmium inhibits the enzymic hydration of the polycyclic benzo(a)pyrene-4,5-oxide molecule competitively, and that of the smaller monocyclic alkene oxide of styrene noncompetitively. The estimated Ki values were below 10 mu mol for hydration of both substrates indicating that cadmium is a very potent inhibitor of epoxide hydration.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008862 Microsomes, Liver Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough. Liver Microsomes,Liver Microsome,Microsome, Liver
D002104 Cadmium An element with atomic symbol Cd, atomic number 48, and atomic weight 112.41. It is a metal and ingestion will lead to CADMIUM POISONING.
D003510 Cyclohexanes Six-carbon alicyclic hydrocarbons.
D004851 Epoxide Hydrolases Enzymes that catalyze reversibly the formation of an epoxide or arene oxide from a glycol or aromatic diol, respectively. Epoxide Hydrase,Epoxide Hydrases,Epoxide Hydratase,Epoxide Hydratases,Epoxide Hydrolase,9,10-Epoxypalmitic Acid Hydrase,Microsomal Epoxide Hydrolase,Styrene Epoxide Hydrolase,9,10 Epoxypalmitic Acid Hydrase,Acid Hydrase, 9,10-Epoxypalmitic,Epoxide Hydrolase, Microsomal,Epoxide Hydrolase, Styrene,Hydrase, 9,10-Epoxypalmitic Acid,Hydrase, Epoxide,Hydrases, Epoxide,Hydratase, Epoxide,Hydratases, Epoxide,Hydrolase, Epoxide,Hydrolase, Microsomal Epoxide,Hydrolase, Styrene Epoxide,Hydrolases, Epoxide
D004852 Epoxy Compounds Organic compounds that include a cyclic ether with three ring atoms in their structure. They are commonly used as precursors for POLYMERS such as EPOXY RESINS. Epoxide,Epoxides,Epoxy Compound,Oxiranes,Compound, Epoxy,Compounds, Epoxy
D004988 Ethers, Cyclic Compounds of the general formula R-O-R arranged in a ring or crown formation. Cyclic Ether,Cyclic Ethers,Ether, Cyclic
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001580 Benzopyrenes A class of chemicals that contain an anthracene ring with a naphthalene ring attached to it. Benzpyrene
D051381 Rats The common name for the genus Rattus. Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus

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