Preferential mutagenesis at G.C base pairs by the anti 3,4-dihydrodiol 1,2-epoxide of 7-methylbenz[a]anthracene.

The racemic anti-dihydrodiol epoxide of 7-methylbenz[a]anthracene preferentially induced mutations at G.C base pairs in the pS189 shuttle vector. Mutations were not randomly distributed throughout the supF target gene, but were concentrated at five hotspots. The hotspots for this agent did not correspond exactly to those produced by any other dihydrodiol epoxide examined to date, indicating that dihydrodiol epoxide structure and reactivity play a major role in determining mutagenic hotspots.