Bioanalytical Mass Spectrometry
Due to the often transient nature of biological free radicals in solution, there has been an increased interest in gaining a more fundamental understanding of the structure and reactivity of radicals in small model systems in the gas phase. The main direction of our research has been to develop new methods for the study of radical ions in the gas phase using mass spectrometric (MS) techniques. In particular, we have employed ion–molecule reactions (IMR) for the study of radical ion reactivity. The model systems include amino acids with reactive amino acid side chains (cysteine, tyrosine, tryptophan), small peptides and DNA nucelobases where the radicals can be generated regiospecifically via various chemical means. Gas‐phase IMR of these radical ions shed light on their structure and provide convenient route to explore their intrinsic reactivity with the potential to study radical migration and radical‐induced damage. For example, we can monitor hydrogen atom transfer (HAT) in glutathione radical: the S‐based (thiyl), reactive radical is rearranging via HAT to a non‐reactive α‐carbon radical.
We also use ion spectroscopy (in IR and UV regions) and theoretical calculations to complement our gas‐phase reactivity studies. In the example below, isomeric thiyl and α‐carbon radicals of homocysteine are distinguished by ion IR spectroscopy.
Lesslie, M.; Yang, Y.; Canty, A. J.; Piacentino, E.; Berthias, F.; Maître, P.; Ryzhov, V. and O'Hair, R. A. J. “Ligand‐induced decarbonylation in diphosphine‐ligated palladium acetates [CH3CO2Pd((PR2)2CH2)]+ (R = Me and Ph)”, Chem. Comm., 2018, DOI: 10.1039/C7CC08944A
Lesslie, M.; Lawler, J. T.; Dang, A.; Korn, J.A.; Bím, D.; Steinmetz, V.; Maître, P.; Tureček, F. and Ryzhov, V. “Cytosine Radical Cations: A Gas‐Phase Study Combining IRMPD Spectroscopy, UVPD Spectroscopy, Ion–Molecule Reactions, and Theoretical Calculations”, ChemPhysChem, 2017, 18, 1293–1301, DOI: 10.1002/cphc.201700281
Lesslie, M.; Lau, J. K.‐C.; Lawler, J. T.; Siu, K. W. M.; Oomens, J.; Berden, G.; Hopkinson, A. C. and Ryzhov, V. “Alkali‐Metal‐Ion‐Assisted Hydrogen Atom Transfer in the Homocysteine Radical.” Chem. Eur. J., 2016, 22, 2243–2246.
Lesslie, M.; Lau, J. K.‐C.; Lawler, J. T.; Siu, K. W. M.; Steinmetz, V.; Maître, P.; Hopkinson, A. C. and Ryzhov, V. “Cysteine Radical/Metal Ion Adducts: A Gas‐Phase Structural Elucidation and Reactivity Study.” ChemPlusChem., 2016, 81, 444–452.
Lesslie, M.; Piatkivskyi, A.; Lawler, J.; Helgren, T.; Osburn, S.; O'Hair, R. A. J.; and Ryzhov, V. “The Effects of Intramolecular Hydrogen Bonding on the Reactivity of Phenoxyl Radicals in Model Systems.” Int. J. Mass Spectrom., 2015, 390, 124–131.
Piatkivskyi, A.; Pyatkivskyy, Y.; Hurt, M. and Ryzhov, V. “Utilization of gas‐phase ion–molecule reactions for differentiation between phospho‐ and sulfocarbohydrates”, Eur. J. Mass Spectrom., 2014, 20, 187–183.
Mishra, E., Worlinsky, J. L., Brückner, C. and Ryzhov, V. “MS/MS Fragmentation Behavior Study of meso‐Phenylporphyrinoids Containing Non‐pyrrolic Heterocycles and meso‐Thienyl‐substituted Porphyrins”. J. Am. Soc. Mass Spectrom., 2014, 25, 18–29.
Osburn, S. and Ryzhov, V., “Ion–Molecule Reactions: Analytical and Structural Tool.” Anal. Chem., 2013, 85, 769–778.
Research Associate, University of Maryland, College Park, 1998–2000
Ph.D., Case Western Reserve University, 1998
M.S., Moscow State University, 1992
Bioanalytical mass spectrometry; gas‐phase ion reactivity and energetics; radical ions of biomolecules, gas‐phase catalysis using metal ion complexes; HPLC and LC/MS assays for monitoring enzyme inhibition (collaboration with Prof. Hagen)