January 2017 Meeting

Speaker: Alexandre Shvartsburg, Wichita State University

Topic: High-Definition FAIMS for Proteomics, Metabolomics, and Structural Characterization Using Isotopologic Shifts

Date: Monday, January 23, 2017

Time: 6:15 pm Dinner, 7:15 pm: Presentation

Location: Shimadzu Scientific Instrument, Inc. Training Center 7100 Riverwood Drive, Columbia, MD 21046 (Directions)

Dinner: Please RSVP to Katherine Fiedler (Katherine.L.Fiedler@fda.hhs.gov) before January 23 if you will be attending the dinner or are a presenting as a vendor.

Abstract: With all the power of modern MS, most biological and environmental samples require substantial prior separations. The traditional chromatography and electrophoresis are now increasingly complemented by ion mobility spectrometry (IMS) in gases. The nonlinear method of differential or field asymmetric waveform IMS (FAIMS) based on the difference between mobilities at high and low electric fields is much more orthogonal to MS than linear IMS based on absolute mobility, which enables exceptionally specific isomer separations.

We will review the prerequisites for high-resolution FAIMS/MS and its exemplary applications. A major topic in proteomics is the localization of post-translational modifications in mixtures of isomeric proteoforms (variants), where MS/MS is limited by the lack of unique fragments. Mixtures of variants up to ~6 kDa with various PTMs are effectively disentangled by FAIMS using synthetic standards and downstream ETD. All D-amino acid containing peptides (DAACP) are likewise resolved from L-analogs. A similar challenge in metabolomics is elucidating the isomeric diversity of lipids that comprises multiple isomer types including transacylation, double bond position, and cis/trans geometry. High-definition FAIMS developed in our lab generally resolves over ~80% of lipid isomers across types, and more in conjunction with OzID for double bond localization. Finally, FAIMS can resolve isotopic isomers (isotopomers) and isotopologues with peak shifts dependent on the geometry. That is conceptually parallel to NMR, enabling a fundamentally new approach to molecular structure characterization based on gas-phase isotopic shifts.