CHARACTERIZATION OF VARIOUS CLASSES OF PROTEIN ADDUCTS

Analysis of the types of protein adducts formed by chemical carcinogen s indicate that adducts may be categorized into various classes accord ing to the nature of the carcinogen as well as the amino acid with whi ch they react. Tryptophan(214) of serum albumin was previously shown t o react specifically with N-sulfonyloxy-N-acetyl-4-aminobiphenyl. The same residue is now shown to also react with the sulfate esters of N-h ydroxy-N-acetyl-2-aminofluorene and N-hydroxy-N, N'-diacetylbenzidine. Thus, Trp-214 appears to be a binding site for a variety of activated N-aryl hydroxamic acids. Epoxides and diol epoxides derived from poly nuclear aromatic hydrocarbons alkylate carboxylic groups in hemoglobin and serum albumin. Because the esters formed are readily hydrolyzed t o dihydrodiols and tetrahydrotetrols which can be determined by GC-MS, it is possible to analyze for a wide range of polyaromatic hydrocarbo n (PAH) epoxide adducts. With this approach it was shown that human su bjects experiencing exposure to ambient levels of environmental PAH do take up and metabolize chrysene and benzo[a]pyrene. Feral, bottom-dwe lling fish inhabiting contaminated waters were also examined. Globin a dducts containing certain dihydroxy groups such as those arising in an ti-diol epoxide adducts were concentrated by boronate affinity chromat ography and further analyzed by HPLC with diode-array UV/visible detec tion. Four compounds were detected that exhibited spectra characterist ic of a polynuclear chromophore. Two of these appeared to be isomers. Further instrumental analysis is needed to elucidate the structure of these unknown putative adducts. A discussion of how these analyses mig ht be conducted as well as their extension to less heavily adducted hu man globin samples is presented.