, Volume 68, Issue 2, pp 129-133

Metabolic activation of aromatic and heterocyclicN-hydroxyarylamines by wild-type and mutant recombinant human NAT1 and NAT2 acetyltransferases

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Abstract

Recombinant human NAT1 and polymorphic NAT2 wild-type and mutantN-acetyltransferases (encoded byNAT2 alleles with mutations at 282/857, 191, 282/590, 341/803, 341/481/803, and 341/481) were expressed inEscherichia coli strains XA90 and/or JM105, and tested for their capacity to catalyze the metabolic activation (viaO-acetylation) of theN-hydroxy (N-OH) derivatives of 2-aminofluorene (AF), and the heterocyclic arylamine mutagens 2-amino-3-methylimidazo [4,5-f]quinoline (IQ), 2-amino-3,4-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Both NAT1 and NAT2 (including all mutant human NAT2s tested) catalyzed the metabolic activation of each of theN-hydroxyarylamines to products that bound to DNA. Metabolic activation of N-OH-AF was greater than that of the heterocyclicN-hydroxyarylamines. The relative capacity of NAT1 versus NAT2 to catalyze activation varied withN-hydroxyarylamine substrate. N-OH-MeIQx and N-OH-PhIP exhibited a relative specificity for NAT2. These results provide mechanistic support for a role of the genetic acetylation polymorphism in the metabolic activation of heterocyclic amine mutagens and carcinogens.