Glutathione transferase catalyzed conjugation of benzo[a]pyrene 7,8-diol 9,10-epoxide with glutathione in human skin

Chemico-biological Interactions
B JernströmP L Grover

Abstract

Glutathione transferase (GST) activity towards racemic as well as the resolved enantiomers of 7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a] pyrene (anti-BPDE) and 1-chloro-2,4-dinitrobenzene (CDNB) was measured in post-microsomal supernatants (PMS) obtained from eight human skin samples. All preparations showed significant activity towards anti-BPDE and an almost exclusive preference for the more tumourigenic (+)-enantiomer. The specific activity towards (+)-anti-BPDE varied about five-fold between different PMS (range 147-781 pmol/min per mg protein) whereas the variation in specific activities towards CDNB was about two-fold (range 30-71 nmol/min per mg protein). The activities obtained with PMS at saturating concentrations of racemic anti-BPDE were about half of the activity towards the (+)-enantiomer indicating that (-)-anti-BPDE competitively inhibits conjugation of the (+)-form. No correlation was evident between the activities towards (+)-anti-BPDE and CDNB implying that different classes of GST isoenzymes participated in the two different reactions. Immunoblot analysis revealed the presence of Class Alpha and Pi isoenzymes whereas Class Mu isoenzymes seemed to be absent in the human skin sa...Continue Reading

References

Jan 1, 1988·Chemico-biological Interactions·M Hall, P L Grover
Jan 1, 1981·Methods in Enzymology·W H Habig, W B Jakoby

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Citations

Jan 1, 1993·Archives of Toxicology·N W ClarkF M Williams
Jun 4, 1993·Biochimica Et Biophysica Acta·S S SinghalY C Awasthi
Jun 16, 2010·Drug Metabolism and Disposition : the Biological Fate of Chemicals·Pramod UpadhyayaStephen S Hecht

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