Heim M H, Blum M, Beer M, Meyer U A
Department of Pharmacology, University of Basel, Switzerland.
J Neurochem. 1991 Oct;57(4):1095-9. doi: 10.1111/j.1471-4159.1991.tb08266.x.
Two rabbit arylamine N-acetyltransferases (NAT1 and NAT2, EC 2.3.1.5) have been cloned and characterized recently in this laboratory. They catalyze the acetylation of primary arylamine and hydrazine drugs and other substrates in the liver, including sulfamethazine, p-aminosalicylic acid, and p-aminobenzoic acid. In the pineal gland, serotonin is metabolized to N-acetylserotonin by an unknown N-acetyl-transferase. Similarity of the liver enzymes and the pineal gland arylalkylamine N-acetyltransferase (AA-NAT) has been suggested, because pineal gland homogenates were shown to metabolize arylamine substrates as p-phenetidine, aniline, or phenylethylamine, and liver homogenates or partially purified liver enzyme preparations catalyzed the N-acetylation of serotonin. The present study was undertaken to elucidate the possible role of NAT1 or NAT2 in serotonin acetylation in the pineal gland. We transiently expressed rNAT1 and rNAT2 genes in COS cells, studied the kinetics of the enzymes produced with various substrates, and compared these data with activities of rabbit pineal glands and livers. These enzymatic studies were complemented with western blot analysis with antibodies against NAT1 and NAT2. Cross-hybridization of rNAT1 or rNAT2 to the gene for the pineal gland AA-NAT was tested by Southern blot studies of genomic rabbit DNA. Our results indicate that although NAT1 is expressed in the pineal gland, it is not involved in the physiologically important step of N-acetylation of serotonin.
本实验室最近克隆并鉴定了两种兔芳胺N - 乙酰基转移酶（NAT1和NAT2，EC 2.3.1.5）。它们催化肝脏中伯芳胺和肼类药物以及其他底物的乙酰化反应，这些底物包括磺胺二甲嘧啶、对氨基水杨酸和对氨基苯甲酸。在松果体中，5-羟色胺通过一种未知的N - 乙酰基转移酶代谢为N - 乙酰5-羟色胺。由于松果体匀浆能代谢如对乙氧基苯胺、苯胺或苯乙胺等芳胺底物，而肝脏匀浆或部分纯化的肝脏酶制剂能催化5-羟色胺的N - 乙酰化反应，因此有人提出肝脏酶与松果体芳烷基胺N - 乙酰基转移酶（AA - NAT）具有相似性。本研究旨在阐明NAT1或NAT2在松果体中5-羟色胺乙酰化反应中可能的作用。我们在COS细胞中瞬时表达rNAT1和rNAT2基因，研究了所产生的酶与各种底物反应的动力学，并将这些数据与兔松果体和肝脏的活性进行比较。这些酶学研究通过使用针对NAT1和NAT2的抗体进行蛋白质印迹分析得到补充。通过对兔基因组DNA的Southern印迹研究，检测了rNAT1或rNAT2与松果体AA - NAT基因的交叉杂交情况。我们的结果表明，尽管NAT1在松果体中表达，但它不参与5-羟色胺N - 乙酰化这一重要的生理步骤。
