13C Labelling and electrospray mass spectrometry reveal a de novo route for inositol biosynthesis in Leishmania donovani parasite

Abstract

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.