Klassen, John - University of Alberta - Department of Chemistry

个人简介

B.Sc., Queen's University Ph.D., University of Alberta

研究领域

Our research program focuses on the development and application of mass spectrometry-based techniques, implemented with a 4.7 tesla Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR MS) equipped with a nanoflow electrospray (nanoES) source, to study the composition, topology and physicochemical properties of protein complexes in the gas and condensed phases. One component of our research program involves the use of time-resolved ion-molecule and ion-dissociation reactions to study the structure and reactivity of gaseous protein assemblies and protein-ligand complexes. These studies are of considerable fundamental importance, providing insight into the intrinsic properties of proteins and protein complexes in the absence of solvent, and are critical to the evolution of mass spectrometry as a powerful tool for proteomics. A second area of research deals with the development of novel strategies to map protein interaction sites and quantify association free energies in the aqueous phase. Some of the specific research projects in our laboratory are described below. Structural Characterization of Protein Assemblies We are using time-resolved dissociation experiments to dissect gaseous protein assemblies to obtain information on composition, quaternary structure and binding energetics. While the concept is straightforward, implementation is hindered by the limited fragmentation observed for the assemblies and an incomplete understanding of the dissociation mechanisms. Using the blackbody infrared radiative dissociation (BIRD) technique, we are investigating the dissociation pathways, kinetics and energetics of assemblies in the gas phase. These studies provide new insight into the dissociation mechanism and the influence of charge and higher order structure thereon and suggest new strategies to increase the structural information available from MS. Mapping Intrinsic Protein-Ligand Interactions Our laboratory is mapping the intermolecular interactions present in gaseous protein-ligand complexes. Using a functional group replacement strategy and a thermal activation technique, the nature and strength of the dominant intermolecular interactions in gaseous protein-oligosaccharide complexes are being determined. Comparison of the gas phase data with solution thermochemistry and crystal structures provides new insights into the structural and energetic role of solvent in association. The protein-ligand interaction energies determined in this work are also important for the development of accurate force fields for improved molecular modeling of biomolecules and their complexes. Binding Affinity and Stoichiometry of Protein-Ligand Complexes Another component of our research program deals with the application of nanoES-FT-ICR MS to evaluate the affinity and stoichiometry of weakly-binding protein-ligand complexes in solution. Quantification of the solution composition based on the gas-phase ion abundance is often hindered by spectral artifacts originating from the nanoES process (e.g. non-specific binding) and gas-phase processes (e.g.decomposition). We are exploring aspects of the nanoES process as well as the relative stability of specific and non-specific protein-ligand complexes to establish experimental conditions that minimize such artifacts.

近期论文

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Carlos A. Sanhueza, Jonathan Cartmell, Amr El-Hawiet, Adam Szpacenko, Elena N. Kitova, Rambod Daneshfar, John Klassen, Kenneth K.-S. Ng, Luiz Eugenio, Pavel I. Kitov, and David R. Bundle "Evaluation of a Focused Virtual Library of Heterobifunctional Ligands for Clostridium difficile Toxins" Organic & Biomolecular Chemistry. 2015, 13(1), 283-298 Ling Han, Elena N. Kitova, Ming Tan, Xi Jiang, Benjamin Pluvinage, Alisdair B. Boraston and John S. Klassen "Affinities of Human Histo-Blood Group Antigens for Norovirus Capsid Protein Complexes" Glycobiology. 2015, 25(2), 170-180 Yuyu Yao, Km Shams-Ud-Doha, Rambod Daneshfar, Elena N. Kitova and John S. Klassen "Quantifying Protein-Carbohydrate Interactions Using Liquid Sample Desorption Electrospray Ionization Mass Spectrometry" J Am Soc Mass Spectrom. 2015, 26(1), 98-106 Perrin Baker, Tyler Ricer, Patrick J. Moynihan, Elena N. Kitova, Marthe T. C. Walvoort, Dustin J. Little, John C. Whitney, Karen Dawson, Joel T. Weadge, Howard Robinson, Dennis E. Ohman, Jeroen D. C. Codée, John S. Klassen, Anthony J. Clarke, P. Lynne Howell "P. aeruginosa SGNH Hydrolase-Like Proteins AlgJ and AlgX Have Similar Topology but Separate and Distinct Roles in Alginate Acetylation" PLoS Pathog. 2014, 10(8), e1004334 Elena N. Kitova, Amr El-Hawiet, and John S. Klassen "Screening Carbohydrate Libraries for Protein Interactions using the Direct ESI-MS Assay. Applications to Libraries of Unknown Concentration" Journal of The American Society for Mass Spectrometry. 2014, 25(11), 1908-1916 Ling Han, Ming Tan, Ming Xia, Elena N. Kitova, Xi Jiang, and John S. Klassen "Gangliosides are Ligands for Human Noroviruses" J. Am. Chem. Soc., 2014, 136(36), 12631-12637 Aneika C Leney, Xuxin Fan, Elena N Kitova, John S. Klassen "Nanodiscs and Electrospray Ionization Mass Spectrometry. A Novel Tool for Screening Glycolipids Against Proteins" Anal. Chem., 2014, 86(11), 5271-5277 Lan Liu, Nobar Jalili, Alyson Baergen, Simon Ng, Justin Bailey, Ratmir Derda, John S. Klassen "Fluorine Bonding Enhances the Energetics of Protein-Lipid Binding in the Gas Phase" Journal of The American Society for Mass Spectrometry. 2014, 25(5), 751-757 Lan Liu, Alyson Baergen, Klaus Michelsen, Elena N. Kitova, Paul D. Schnier, John S. Klassen "Energetics of Intermolecular Hydrogen Bonds in a Hydrophobic Protein Cavity" Journal of The American Society for Mass Spectrometry. 2014, 25(5), 742-750 Wolfram F, Kitova EN, Robinson H, Walvoort M, Codée JD, Klassen JS, Howell PL "Catalytic mechanism and mode of action of the periplasmic alginate epimerase AlgG" J Biol Chem. 2014, 289(9),6006-6019 Murase T, Eugenio L, Schorr M, Hussack G, Tanha J, Kitova EN, Klassen JS, Ng KK "Structural Basis for Antibody Recognition in the Receptor-Binding Domains of Toxins A and B from Clostridium difficile" J Biol Chem. 2014, 289(4), 2331-2343 Jafari MR, Deng L, Kitov PI, Ng S, Matochko WL, Tjhung KF, Zeberoff A, Elias A, Klassen JS, Derda R "Discovery of Light-Responsive Ligands through Screening of a Light-Responsive Genetically Encoded Library" ACS Chem Biol. 2014, 9(2), 443-450 Hong Lin, Elena N. Kitova, John S. Klassen "Measuring Positive Cooperativity Using the Direct ESI-MS Assay. Cholera Toxin B Subunit Homopentamer Binding to GM1 Pentasaccharide" Journal of The American Society for Mass Spectrometry. 2014, 25(1), 104-110 Ling Han, Elena N. Kitova, Ming Tan, Xi Jiang, John S. Klassen "Identifying Carbohydrate Ligands of a Norovirus P Particle using a Catch and Release Electrospray Ionization Mass Spectrometry Assay" Journal of The American Society for Mass Spectrometry. 2014, 25(1), 111-119 Hong Lin, Elena N. Kitova , and John S. Klassen "Quantifying Protein–Ligand Interactions by Direct Electrospray Ionization-MS Analysis: Evidence of Nonuniform Response Factors Induced by High Molecular Weight Molecules and Complexes" Anal. Chem., 2013, 85(19), 8919-8922 Amr El-Hawiet , Elena N. Kitova , and John S. Klassen "Quantifying Protein Interactions with Isomeric Carbohydrate Ligands Using a Catch and Release Electrospray Ionization-Mass Spectrometry Assay" Anal. Chem., 2013, 85(16), 7637-7644 Yixuan Zhang, Lu Deng, Elena N. Kitova, John S. Klassen "Dissociation of Multisubunit Protein–Ligand Complexes in the Gas Phase. Evidence for Ligand Migration" Journal of The American Society for Mass Spectrometry. 2013, 24, 1573-1583 Lu Deng, Elena N. Kitova, John S. Klassen. "Mapping Protein–Ligand Interactions in the Gas Phase Using a Functional Group Replacement Strategy. Comparison of CID and BIRD Activation Methods" Journal of The American Society for Mass Spectrometry. 2013, 24, 988-996 Fumie X. Sunahori, Guochun Yang, Elena N. Kitova, John S. Klassen and Yunjie Xu. "Chirality recognition of the protonated serine dimer and octamer by infrared multiphoton dissociation spectroscopy" Phys. Chem. Chem. Phys., 2013, 15, 1873-1886 Lu Deng, Elena N. Kitova, and John S. Klassen. "Dissociation Kinetics of the Streptavidin-Biotin Interaction Measured using Direct Electrospray Ionization Mass Spectrometry Analysis" Journal of The American Society for Mass Spectrometry. 2013, 24(1), 49-56