Short bio: Dajana Vuckovic just joined Concordia University as an Assistant Professor in Bioanalytical Chemistry at the Department of Chemistry and Biochemistry. She holds Honours B.Sc. in Chemistry from the University of Toronto and Ph.D. in Analytical Chemistry from the University of Waterloo.  Her doctoral research under supervision of Prof. Janusz Pawliszyn focused on the development of in vivo solid-phase microextraction methodology for global metabolomics and small rodent pharmacokinetic studies.  As NSERC Postdoctoral Fellow at the University of Toronto with Prof. Andrew Emili, she developed novel chemical proteomics workflow for the determination of protein targets of drugs. She is the recipient of several awards including Johnson & Johnson Young Scientist Scholarship and 2010 Douglas E. Ryan Graduate Student Award by Canadian Society for Chemistry. She has co-authored 28 publications and 8 book chapters to date, and contributed 30 oral and 10 poster presentations at national and international conferences. She is currently the Editor of Sample Preparation, and an Editorial Board Member of Bioanalysis and Journal of Integrated Omics. At Concordia, she plans to establish a state-of-the-art research program in analytical and clinical metabolomics with particular focus on the development of new strategies to improve metabolome coverage of unstable and low abundance metabolites and the development of improved diagnostic methods for bipolar disorder.

Abstract :

The omission of metabolism quenching step in metabolomics studies of biological fluids can result in undesirable changes in metabolome composition and adversely impact subsequent data quality and interpretation.  In vivo solid-phase microextraction (SPME) is a new and effective sample preparation method for untargeted LC-MS metabolomics studies which incorporates metabolism quenching step directly during the sampling process and eliminates the need for blood withdrawal. In this study, the performance of in vivo SPME sampling of circulating mouse blood was compared against the traditional approaches based on blood withdrawal in combination with solvent precipitation, ultrafiltration and ex vivo SPME in order to study the effect of single carbamazepine dose on endogenous metabolism of mice. The overall metabolite coverage of SPME was lower than that of solvent precipitation and ultrafiltration when a single coating was used for extraction, but can be further enhanced with the use of complementary coatings. More importantly, in vivo SPME successfully captured unstable metabolites not observed by any of the traditional methods, with approximately 4% unique SPME features including important metabolites such as carotenes and β-NAD and improved quantitation of many unstable metabolites, for example glutathione or adenosine. Overall, we demonstrate that in vivo SPME can play an important role in untargeted studies to accurately capture metabolome at the time of sampling as well as in targeted studies of unstable and short-lived metabolites. The second part of the talk will focus on a novel chemical proteomics method for the determination of protein targets of bioactive molecules using chromatographic fractionation. The proposed method, called target identification by chromatographic co-elution (TICC), relies on the observable shift of the elution profile of a small ligand when the ligand is bound to a protein under non-denaturing chromatographic conditions. The methodology was validated using well-studied ligands with known interacting protein partners, such as interaction of trichostatin A with HDAC1 (K_i=3.4 nM) and sordarin with ELF2 (K_d = 1.26 µM). We also successfully identified ASC1 and DAK1 as novel targets of A77636 showing the capability of technique for de novo target deconvolution and its promise in both phenotype-based and target-centric discovery pipelines.