Metabolite profiling of mitochondria and whole cells in S. cerevisiae using LC/MS and GC/MS

A new approach to screen yeast metabolites in whole cells as well as in mitochondria is reported. The platform combines different analytical methods by broadening them by applying metabolite profiling algorithms on unknown peaks. Phosphorous compounds, TCA-cycle acids and lipids are measured from different compartments of yeast cells. The lipid screening consists of ESI+ and ESI- LC/MS in full scan mode, which enable us to cover compounds such as phosphatodylcholines, sphingolipids, ceramides, lysophosphatidylcholines, phosphatodylinositols, phosphoserines, diacylglycerols, and triacylglycerols. In addition to LC/MS, GC/MS has been used for profiling of small molecular weight metabolites (for example small acids) from the yeast cells and mitochondria. Samples have been analysed with and without pretreatment and profiling results have been compared with each others. For pretreatment, solid phase extraction methods have been developed by testing different solvents. Also different derivatizing reagents suitable for different sample classes have been tested. We are primarily interested in differential metabolite profiling, i.e. assessing patterns of changes of metabolite composition within cellular compartments or whole cells across various environmental conditions or time points. For that purpose we are applying a variety of multivariate statistical approaches that will be presented.