Kawamura Akane, Westwood Isaac, Wakefield Larissa, Long Hilary, Zhang Naixia, Walters Kylie, Redfield Christina, Sim Edith
Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom.
Biochem Pharmacol. 2008 Apr 1;75(7):1550-60. doi: 10.1016/j.bcp.2007.12.012. Epub 2008 Jan 5.
There is increasing evidence that human arylamine N-acetyltransferase type 1 (NAT1, EC 2.3.1.5), although first identified as a homologue of a drug-metabolising enzyme, appears to be a marker in human oestrogen receptor positive breast cancer. Mouse Nat2 is the mouse equivalent of human NAT1. The development of mouse models of breast cancer is important, and it is essential to explore the biological role of mouse Nat2. We have therefore produced mouse Nat2 as a recombinant protein and have investigated its substrate specificity profile in comparison with human NAT1. In addition, we have tested the effects of inhibitors on mouse Nat2, including compounds which are endogenous and exogenous steroids. We show that tamoxifen, genistein and diethylstilbestrol inhibit mouse Nat2. The steroid analogue, bisphenol A, also inhibits mouse Nat2 enzymic activity and is shown by NMR spectroscopy, through shifts in proton peaks, to bind close to the active site. A three-dimensional structure for human NAT1 has recently been released, and we have used this crystal structure to generate a model of the mouse Nat2 structure. We propose that a conformational change in the structure is required in order for ligands to bind to the active site of the protein.
越来越多的证据表明，人类芳基胺N - 乙酰基转移酶1型（NAT1，EC 2.3.1.5），尽管最初被鉴定为一种药物代谢酶的同源物，但似乎是人类雌激素受体阳性乳腺癌的一个标志物。小鼠Nat2是人类NAT1的小鼠对应物。乳腺癌小鼠模型的开发很重要，探索小鼠Nat2的生物学作用至关重要。因此，我们制备了重组蛋白形式的小鼠Nat2，并与人类NAT1比较研究了其底物特异性谱。此外，我们测试了抑制剂对小鼠Nat2的影响，包括内源性和外源性类固醇化合物。我们发现他莫昔芬、染料木黄酮和己烯雌酚可抑制小鼠Nat2。类固醇类似物双酚A也抑制小鼠Nat2的酶活性，并且通过核磁共振光谱法，通过质子峰的位移表明其靠近活性位点结合。最近公布了人类NAT1的三维结构，我们利用该晶体结构生成了小鼠Nat2结构的模型。我们提出，为使配体与蛋白质的活性位点结合，结构需要发生构象变化。
