Reactivity and adduct formation of a polyaromatic hydrocarbon, 7-bromomethylbenz[a]anthracene, with chromatin histone proteins. 
The alkylation of histones by the direct-acting carcinogen 7-bromomethylbenz[a]anthracene was demonstrated both in vivo and in vitro.  The relative molar reactivity for mouse liver histones in vivo was H3 greater than H1 greater than H2b greater than H4 greater than H2a.  The in vitro modification of histone H3 was examined in detail.  Amino acid adducts stable to acid hydrolysis were separated after acetylation by reversed-phase high-performance liquid chromatography and characterized using ultraviolet absorbance spectra and synthetic amino acid adduct standards.  Three major adducts were observed and tentatively identified as cysteinyl, lysyl and histidinyl adducts of histone H3.