Ion/ion Chemistry and Ion Trap Approaches for the Structural Characterization of the Lipidome

Purdue University, West Lafayette IN

Investigators

Abstract

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Scott McLuckey and his group at Purdue University are developing novel approaches for the structural characterization of lipid molecules. The reactivities of molecules and the roles that they play are intimately tied to their structures. Molecules comprised of the same atoms but with different linkages between atoms (i.e., isomers) can have markedly different reactivities. The chemistries associated with all forms of life are replete with examples in which isomeric molecules play key and unique roles. As a class of biomolecules, lipids are emerging as highly informative markers of the biological state of an organism. The lipid complement of an organism is referred to as its ‘lipidome’. Many examples of isomerism have been identified in lipidomes, many of which are already known to be biologically significant. However, tools to characterize the structural diversity of the lipidome are lacking. Professor McLuckey and his students are inventing new tools and approaches to characterize the lipidome, which will enable the scientific community to generate a deeper understanding of the chemistry of life. This project seeks to develop novel ion/ion reaction and electrodynamic ion trap approaches for the structural characterization of ions derived from lipids present in complex mixtures. An underlying theme of the work is to employ the most sensitive approach to ionization while using gas-phase ion/ion reactions to convert the initially formed ion-type to alternate ion-types that yield structural details that a single ion-type alone cannot provide. Collision-induced dissociation under a range of conditions will be used to probe the ion-types generated using various reagents. Isomer distinction, for example, will be based on differences in product ion identities and/or abundances and differences in dissociation rates. The even-electron lipid ions generated directly by electrospray ionization will be subjected to reactions that will lead multiple alternate ion-types that include odd-electron ions, metal-containing ions, and combinations thereof. This work has the potential to yield a flexible means for the structural characterization of a variety of lipids present in complex mixtures and, as such, could provide valuable enabling analytical technology for the study of frontline questions in lipidomics and lipid biology. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.