中文摘要：

Arylamine N-acetyltransferases (NAT， EC 2.3.1.5 ) 从乙酰辅酶 A (AcCoA ) 催化乙酰组转移到主要 arylamines 并且在药和致癌物的新陈代谢和 bioactivation 起一个很重要的作用。实验表明 His-107 是可能的负责调停的残余乙酰转移。acetylation 过程的完整的催化机制被密度检验了功能的理论。如果乙酰组直接从施主被转移，结果显示那， p-nitrophenyl 醋酸盐到领受人，半胱氨酸，高激活精力将是一个大阻碍者。当 His-107 帮助了转移过程时，这些精力在 2025 kJ/mol 的一点范围落下。不管多么当 protonated His-107 调停了时反应，激活精力被掉了大约 7385 kJ/mol。我们的计算强烈支持了经历 thiolate-imidazolium 对的酶 acetylation 机制，并且从实验验证了专横。

英文摘要：

Arylamine N-acetyltransferases （NATs, EC 2.3.1.5） catalyze an acetyl group transfer from acetyl coenzyme A （AcCoA） to primary arylamines and play a very important role in the metabolism and bioactivation of drugs and carcinogens. Experiments revealed that His-107 was likely the residues responsible for mediating acetyl transfer. The full catalytic mechanism of acetylation process has been examined by density functional theory. The results indicate that, if the acetyl group is directly transferred from the donor, p-nitrophenyl acetate, to the acceptor, cysteine, the high activation energy will be a great hindrance. These energies have dropped in a little range of 20-25 kJ/mol when His-107 assisted the transfer process. However, when protonated His-107 mediated the reaction, the activation energies have been dropped about 73-85 kJ/mol. Our calculations strongly supported an enzyme acetylation mechanism that experiences a thiolate-imidazolium pair, and verified the presumption from experiments.