Analyses of complex biological and environmental sample mixtures require state-of-the-art instruments that can resolve different components of a mixture, provide individual molecular identities, yield relative abundance or concentration information, and unravel potential molecular interactions among the various constituents of a complex sample at a high level of confidence. Our studies are focused on biomedical and environmental research and improving performance characteristics of modern mass spectrometers to address the demanding analytical requirements for comprehensive characterization of complex mixtures in the emerging areas of “x-omics”. Here, we use “x-omics” to refer to inclusive study of complex systems such as the components of a living organism (e.g., genomics, lipidomics, metabolomics, proteomics, etc.) and/or a non-living system (e.g., petroleumics). Ideally, for complete characterization of a complex ensemble, three general questions regarding the (i) types, (ii) concentrations, and (iii) nature of the interactions of all individual components of a mixture under the investigation must be addressed (often, as a function of time). Our research addresses all of the above mentioned three areas and includes activities from instrument development endeavors, experimental approaches, and theoretical calculations.
Specifically, our research group’s interests include structural analysis of complex molecules by collision-induced dissociation (CID), electron capture dissociation (ECD), and photodissociation in Fourier Transform Ion Cyclotron Resonance (FT-ICR) Mass Spectrometry and development of high performance analytical devices and multidimensional methods. In addition to FT-ICR instruments, we are fortunate to have access to other high performance mass spectrometers such as Orbitrap and high resolution reflectron time-of-flight (TOF) mass spectrometers, equipped with ion mobility devices, to carry out complex and multidimensional analyses. We aim to develop methodologies that can address the need for comprehensive characterization of complex “real world” samples at the molecular level.
To address our long- and short-term goals, we are utilizing various “hard” and “soft” ionization techniques such as electron impact ionization (EI), chemical ionization (CI), self chemical ionization (SCI), electrospary ionization (ESI) and most recently radiofrequency ionization (RFI) for sample fingerprinting and understanding chemical interactions in complex mixtures at a high level confidence. Several of our current research projects focus on reducing mass spectral detection limits (e.g., the use of cryofocusing for GC/MS analysis of volatile compounds and external ion accumulation in ESI experiments) for the analysis of environmental toxins and biomolecules in various areas of “x-omics” addressing emerging needs both in instrumental development and introduction of multidimensional techniques, that include ion mobility spectrometry (IMS), experimental measurement of thermochemical properties such proton affinities (PAs) and gas phase basicites (GB) and their theoretical calculations, for comprehensive characterization of complex samples mixtures.
Also a major portion of our current research focuses on biomarker identification for early and non-invasive detection of human diseases such as cancer. In this endeavor, we attempt to address contemporary challenges related to the fundamental chemistry, bioinformatics, and applied aspects of complex data analysis. For instance, a major portion of our efforts is focused on utilizing gas-phase ion-molecule reaction kinetics such as hydrogen-deuterium exchange (HDX) combined with IMS conformational analyses to improve structural characterization of proteins and their fragments in “bottom-up” and “top-down” proteomics. In these two proteomic approaches, either digested (in bottom-up) or intact (in top-down) proteins are fragmented using activational {e.g., collision-induced dissociation (CID), infrared multiphoton dissociation (IRMPD)} and/or non-activational {e.g., electron capture dissociation (ECD) and electron transfer dissociation (ETD)} dissociation techniques. The product fragment ions are searched against databases or theoretical MS/MS spectra using computer algorithms for protein/peptide sequence identification.
Reliability of protein/peptide identification using computer algorithms depends, in part, on the extent and types of protein/peptide dissociation products. Computer-based protein/peptide identification is usually performed without (or with little) insight into the rules that govern peptide dissociation and fragmentation. However, for accurate bioinformatics-based MSn sequencing of proteins/peptides, basic knowledge of the chemistry and mechanisms of gas-phase peptide fragmentation are crucial. For instance, unaccounted “ion rearrangements” can impede gas-phase protein sequencing and our systematically designed tandem MS research in this area addresses the issues related to amino acid “sequence scrambling” in structural and biological mass spectrometry.
Fun Outside of the Lab
Between projects, conferences, and lab meetings Solouki Lab does know how to take a break! To celebrate special achievements or special days, we go on picnics, trips to the zoo, lunch, and other various places!
Contact Information:
Touradj Solouki
(254) 710-2678
Touradj_SoloukiATbaylor.edu
