Hein David W, Doll Mark A
Department of Pharmacology and Toxicology and James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY, 40202, USA.
Department of Pharmacology and Toxicology, University of Louisville Health Sciences Center, Kosair Charities CTR-Room 303, 505 South Hancock Street, Louisville, KY, 40202, USA.
Arch Toxicol. 2017 Aug;91(8):2827-2835. doi: 10.1007/s00204-017-1989-7. Epub 2017 May 18.
Human N-acetyltransferase 2 (NAT2) catalyzes the N-acetylation of numerous aromatic amine drugs such as sulfamethazine (SMZ) and hydrazine drugs such as isoniazid (INH). NAT2 also catalyzes the N-acetylation of aromatic amine carcinogens such as 2-aminofluorene and the O- and N,O-acetylation of aromatic amine and heterocyclic amine metabolites. Genetic polymorphism in NAT2 modifies drug efficacy and toxicity as well as cancer risk. Acetyltransferase catalytic activities and heat stability associated with six novel NAT2 haplotypes (NAT26C, NAT214C, NAT214D, NAT214E, NAT217, and NAT218) were compared with that of the reference NAT2*4 haplotype following recombinant expression in Escherichia coli. N-acetyltransferase activities towards SMZ and INH were significantly (p < 0.0001) lower when catalyzed by the novel recombinant human NAT2 allozymes compared to NAT2 4. SMZ and INH N-acetyltransferase activities catalyzed by NAT2 14C and NAT2 14D were significantly lower (p < 0.001) than catalyzed by NAT2 6C and NAT2 14E. N-Acetylation catalyzed by recombinant human NAT2 17 was over several hundred-fold lower than by recombinant NAT2 4 precluding measurement of its kinetic or heat inactivation constants. Similar results were observed for the O-acetylation of N-hydroxy-2-aminofluorene and N-hydroxy-2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine and the intramolecular N,O-acetylation of N-hydroxy-N-acetyl-2-aminofluorene. The apparent V of the novel recombinant NAT2 allozymes NAT2 6C, NAT2 14C, NAT2 14D, and NAT2 14E towards AF, 4-aminobiphenyl (ABP), and 3,2'-dimethyl-4-aminobiphenyl (DMABP) were each significantly (p < 0.001) lower while their apparent K values did not differ significantly (p > 0.05) from recombinant NAT2 4. The apparent V catalyzed by NAT2 14C and NAT2 14D were significantly lower (p < 0.05) than the apparent V catalyzed by NAT2 6C and NAT2 14E towards AF, ABP, and DMABP. Heat inactivation rate constants for recombinant human NAT2 14C, 14D, 14E, and 18 were significantly (p < 0.05) higher than NAT2 4. These results provide further evidence of genetic heterogeneity within the NAT2 slow acetylator phenotype.
人类N - 乙酰基转移酶2（NAT2）催化多种芳香胺类药物（如磺胺二甲嘧啶（SMZ））和肼类药物（如异烟肼（INH））的N - 乙酰化反应。NAT2还催化芳香胺类致癌物（如2 - 氨基芴）的N - 乙酰化反应以及芳香胺和杂环胺代谢产物的O - 乙酰化和N，O - 乙酰化反应。NAT2基因多态性会改变药物疗效、毒性以及癌症风险。在大肠杆菌中进行重组表达后，将六种新型NAT2单倍型（NAT26C、NAT214C、NAT214D、NAT214E、NAT217和NAT218）的乙酰转移酶催化活性和热稳定性与参考NAT2*4单倍型进行了比较。与NAT2 4相比，新型重组人NAT2同工酶催化时，对SMZ和INH的N - 乙酰转移酶活性显著降低（p < 0.0001）。NAT2 14C和NAT2 14D催化的SMZ和INH N - 乙酰转移酶活性显著低于（p < 0.001）NAT2 6C和NAT2 14E催化的活性。重组人NAT2 17催化的N - 乙酰化反应比重组NAT2 4低数百倍，无法测定其动力学或热失活常数。对于N - 羟基 - 2 - 氨基芴和N - 羟基 - 2 - 氨基 - 1 - 甲基 - 6 - 苯基咪唑[4,5 - b]吡啶的O - 乙酰化反应以及N - 羟基 - N - 乙酰 - 2 - 氨基芴的分子内N，O - 乙酰化反应，也观察到了类似结果。新型重组NAT2同工酶NAT2 6C、NAT2 14C、NAT2 14D和NAT2 14E对AF、4 - 氨基联苯（ABP）和3,2'-二甲基 - 4 - 氨基联苯（DMABP）的表观V 均显著降低（p < 0.001），而它们的表观K 值与重组NAT2 4相比无显著差异（p > 0.05）。NAT2 14C和NAT2 14D催化的表观V 显著低于（p < 0.05）NAT2 6C和NAT2 14E对AF、ABP和DMABP催化的表观V 。重组人NAT2 14C、14D、1
