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BINDING OF POLYCHLORINATED BIPHENYLS CLASSIFIED AS EITHER PHENOBARBITONE-, 3-METHYLCHOLANTHRENE- OR MIXED-TYPE INDUCERS TO CYTOSOLIC AH RECEPTOR
Citation:
Bandiera, A., S. Safe, AND A. Okey. BINDING OF POLYCHLORINATED BIPHENYLS CLASSIFIED AS EITHER PHENOBARBITONE-, 3-METHYLCHOLANTHRENE- OR MIXED-TYPE INDUCERS TO CYTOSOLIC AH RECEPTOR. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-82/369.
Description:
It has been postulated that reversible, high-affinity binding of 3-methyl-cholanthrene (MC)-type inducers to a receptor protein (the Ah receptor) in hepatic cytosol is essential for induction of aryl hydrocarbon hydroxylase (AHH) enzymic activity. To test this postulate, the binding affinities of 16 highly purified, synthetic chlorinated biphenyl (PCB) congeners, which have been categorized either as phenobarbitone (PB)-, MC- or mixed (PB + MC)-type inducers of cytochrome P-450-dependent monooxygenases have been examined. The affinity of individual biphenyl congeners for the receptor was determined by their competition with 2,3,7,8-(3 sup H) tetrachlorodibenzo-p-dioxin ((3 sup H)TCDD) for specific cytosolic binding sites as measured by sucrose density gradient analysis following dextran-charcoal treatment.