Seminar Series

Liquid Chromatography Mass Spectrometry Methods for Investigating Osmolytes and Related One-Carbon Metabolites in Health ad Disease


Chris McEntyre Final Ph.D. Seminar


Time & Place

Fri, 16 Dec 2016 11:00:00 NZDT in Rutherford Room 531

All are welcome


Organic osmolytes are methylamines, polyols, or amino acids that are essential for cell volume regulation. Some have other important biochemical roles. For example, N,N,Ntrimethylglycine (betaine) is an osmolyte that also acts as a methyl group donor in onecarbon metabolism. Previous methods for the analysis of betaine and its metabolite N,Ndimethylglycine (DMG) used derivatization and high performance liquid chromatography with ultra violet detection (HPLC-UV). They required a long sample run time, and often lacked specificity. Liquid chromatography - tandem mass spectrometry (LC-MS/MS) methods were developed with the aim of improving the analysis of betaine and other osmolytes. The objective was to measure some compounds that act as osmolytes, including: betaine; glycerophosphorylcholine (GPC); taurine; myo-inositol; sorbitol; and trimethylamine-N-oxide (TMAO), as well as some related metabolites. The use of LCMS/MS improved the analysis of many osmolytes compared to previous HPLC-UV methods, and the number of osmolytes that could be analysed was increased. To demonstrate applications for these methods, samples from overweight people with type 2 diabetes were analysed to improve knowledge of how osmolytes interact with other metabolites, and their potential use as risk markers in disease. The discovery of the previously unknown metabolite, N,N-dimethylglycine-N-oxide, in human samples suggests that a re-evaluation of the widely accepted pathway for choline metabolism may be required.