In this paper we provide evidence for the presence of a de novo route for myo-inositol biosynthesis in the protozoan parasite Leishmania donovani, by the application of 13C labelling and electrospray ionisation mass spectrometry (ESMS). For this myo-[1-13C]inositol is prepared from D-[6-13C]glucose and biosynthetically incorporated in the parasite promastigote cell culture. Biosynthetic phosphatidylinositol (PI) and its hydrolysis products glycero-PI and inositol are analysed by ESMS and the isotopomeric ratio determined. The incorporation experiments show substantial isotopic dilution, indicating the presence of myo-inositol 1-phosphate synthase (MIP synthase) enzyme in the parasite; this is further confirmed by incorporation of D-[6-13C]glucose in the parasite phosphatidylinositol.
本文通过应用13C标记和电喷雾离子化质谱(ESMS),为原生动物寄生虫利什曼原虫(Leishmania donovani)中存在一条从头开始的肌醇
生物合成途径提供了证据。为此,我们通过D-[6-13C]
葡萄糖制备了肌-[1-13C]肌醇,并将其
生物合成性地整合到寄生虫前鞭毛体
细胞培养物中。通过ESMS分析了
生物合成的
磷脂酰肌醇(
PI)及其
水解产物
甘油磷脂酰肌醇和肌醇,并确定了同位素异构体的比例。整合实验显示出显著的同位素稀释,表明寄生虫中存在肌醇-1-
磷酸合酶(MIP合酶);通过将D-[6-13C]
葡萄糖整合到寄生虫的
磷脂酰肌醇中进一步证实了这一点。