Chiba K, Kobayashi K, Itoh K, Itoh S, Chiba T, Ishizaki T, Kamataki T
Department of Clinical Pharmacology, International Medical Center of Japan, Tokyo.
Eur J Pharmacol. 1995 May 26;293(1):97-100. doi: 10.1016/0926-6917(95)90023-3.
N-oxygenation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a dopaminergic neurotoxin, was studied using recombinant rat liver flavin-containing monooxygenase (FMO), FMO1A1, expressed in yeast cells. The mean (+/- S.D.) kinetic parameters of MPTP N-oxygenation were: Km = 1.8 +/- 0.5 microM, Vmax = 9.5 +/- 1.6 nmol/mg per min, and Vmax/Km = 4.6 +/- 0.5 ml/mg per min. n-Octylamine, an activator of FMO, enhanced the MPTP N-oxygenation activity by 51%, while methimazole, thiobenzamide and alpha-naphthylthiourea, alternate substrates of FMO, inhibited it by 27.4, 68.0 and 59.2%, respectively. The results indicate that MPTP is efficiently N-oxygenated by the recombinant rat liver FMO1A1, and that the responses to the modulators of FMO activity found in the recombinant rat liver FMO1A1 resemble those of mouse and rat liver microsomes as reported previously. The findings suggest that the recombinant FMO expressed in yeast cells is considered as a useful tool to study an involvement of FMO in the metabolism of environmental toxins or chemicals. In addition, FMO1A1 appears to be one of the predominant enzymes responsible for the N-oxygenation of MPTP at least in rat liver.
使用在酵母细胞中表达的重组大鼠肝脏含黄素单加氧酶（FMO）FMO1A1，对多巴胺能神经毒素1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）的N-氧化作用进行了研究。MPTP N-氧化的平均（±标准差）动力学参数为：Km = 1.8±0.5微摩尔，Vmax = 9.5±1.6纳摩尔/毫克每分钟，Vmax/Km = 4.6±0.5毫升/毫克每分钟。FMO的激活剂正辛胺使MPTP N-氧化活性提高了51%，而FMO的替代底物甲巯咪唑、硫代苯甲酰胺和α-萘基硫脲分别使其抑制了27.4%、68.0%和59.2%。结果表明，MPTP可被重组大鼠肝脏FMO1A1有效地进行N-氧化，并且在重组大鼠肝脏FMO1A1中发现的对FMO活性调节剂的反应与先前报道的小鼠和大鼠肝脏微粒体的反应相似。这些发现表明，在酵母细胞中表达的重组FMO被认为是研究FMO在环境毒素或化学物质代谢中作用的有用工具。此外，FMO1A1似乎至少在大鼠肝脏中是负责MPTP N-氧化的主要酶之一。
