Research in the Wysocki group is separated into three broad areas: (1) determination of peptide dissociation mechanisms as a means for improving programs used for automated sequencing of peptides and proteins, (2) surface characterization of organic thin films, and (3) implementation of surface-induced dissociation onto commercial time-of-flight instruments. The research involves collisions of selected reactive and non-reactive ions with well-ordered surfaces (e.g., self-assembled monolayer films of alkanethiols on gold;Langmuir-Blodgett films). The nature of the surface, the type of projectile ion, and the collision energy are the major experimental variables that are explored.
Research in progress on biomolecules is addressing several different questions involving singly and multiply protonated peptides. All of the related projects are designed to increase the current understanding of the hydrogen bonding interactions and fragmentation patterns of activated protonated peptides. The long range goals of this work are to provide additional "rules" that can be used to enhance automated primary sequencing of peptides and proteins by tandem mass spectrometry and, ultimately, to relate information on gas-phase fragmentation patterns and energetics of dissociation to peptide and protein conformation.
Major aims of our surface characterization research are to determine whether the ion/surface chemistry that is detected when low-energy (eV), gas-phase polyatomic ions collide with a well-ordered surface can be used to quantitate the composition of mixed-composition films and to characterize electron transfer through organic thin films in the absence of solvent. Model compounds ("probe ions") are used to define the reactivity of projectile ions with various functional groups at the surface. Projectile ions used include small, odd-spin species such as distonic radical cations and their conventional counterparts; small aromatic compounds with electron-donating and electron-withdrawing groups; large, refractory molecules such as buckminsterfullerene (C60). These different categories of reagents provide distinct types of information on the mechanisms of electron and atom transfer from surfaces to probe ions and on the analytical utility of ion/surface reactions for surface characterization.
A third area of research is the development of improved mass spectrometers for structural characterization of large molecules. Instruments that allow low-energy ion-surface collisions are not available commercially. Commercial MALDI-TOF(matrix-assisted laser desorption time-of- flight) instruments do not have an efficient means of fragmenting the ions. We have recently shown that surface-induced dissociation can be accomplished with good resolution in a sector/time-of-flight instrument and will extend this work to a commercial MALDI system.
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Cheng, G., V.H. Wysocki, and M.A. Cusanovich. 2006. Local stability of Rhodobacter capsulatus cytochrome c(2) probed by solution phase hydrogen/deuterium exchange and mass spectrometry. Journal of the American Society of Mass Spectrometry (in press).
Scaraffia, P.Y., Q. Zhang, V.H. Wysocki, J. Isoe, and M.A. Wells. 2006. Analysis of whole body ammonia metabolism in Aedes aegypti using [(15)N]-labeled compounds and mass spectrometry. Insect Biochemistry and Molecular Biology 36: 614-622.
Smith, L.L., K.A. Herrmann, and V.H. Wysocki. 2006. Investigation of gas phase ion structure for proline-containing b(2) ion. Journal of the American Society of Mass Spectrometry 17: 20-28.
Herrmann, K.A., A. Somogyi, V.H. Wysocki, L. Drahos, and K. Vekey. 2005. Combination of sustained off-resonance irradiation and on-resonance excitation in FT-ICR. Analytical Chemistry 77: 7626-7638.
Huang, Y., J.M. Triscari, G.C. Tseng, L. Pasa-Tolic, M.S. Lipton, R.D. Smith, and V.H. Wysocki. 2005. Statistical characterization of the charge state and residue dependence of low-energy CID peptide dissociation patterns. Analytical Chemistry 77: 5800-5813.
Zhang, Q., V.H. Wysocki, P.Y. Scaraffia, and M.A. Wells. 2005. Fragmentation pathway for glutamine identification: loss of 73 Da from dimethylformamidine glutamine isobutyl ester. Journal of the American Society of Mass Spectrometry 16: 1192-1203.
Herrmann, K.A., V.H. Wysocki, and E.R. Vorpagel. 2005. Computational investigation and hydrogen/deuterium exchange of the fixed charge derivative tris(2,4,6-trimethoxyphenyl) phosphonium: implications for the aspartic acid cleavage mechanism. Journal of the American Society of Mass Spectrometry 16: 1067-1080.
Wysocki, V.H., K.A. Resing, Q. Zhang, and G. Cheng. 2005. Mass spectrometry of peptides and proteins. Methods 35: 211-222.
Gamage, C.M., F.M. Fernandez, K. Kuppannan, and V.H. Wysocki. 2004. Submicrosecond surface-induced dissociation of peptide ions in a MALDI TOF MS. Analytical Chemistry 76: 5080-5091.
Abeytunga, D.T., J.J. Glick, N.J. Gibson, L.A. Oland, A. Somogyi, V.H. Wysocki, and R. Polt. 2004. Presence of unsaturated sphingomyelins and changes in their composition during the life cycle of the moth Manduca sexta. Journal of Lipid Research 45: 1221-1231.
Tsaprailis, G., H. Nair, W. Zhong, K. Kuppannan, J.H. Futrell, and V.H. Wysocki. 2004. A mechanistic investigation of the enhanced cleavage at histidine in the gas-phase dissociation of protonated peptides. Analytical Chemistry 76: 2083-2094.
Huang, Y., J.M. Triscari, L. Pasa-Tolic, G.A. Anderson, M.S. Lipton, R.D. Smith, and V.H. Wysocki. 2004. Dissociation behavior of doubly-charged tryptic peptides: correlation of gas-phase cleavage abundance with ramachandran plots. Journal of the American Chemical Society 126: 3034-3035.
Fernandez, F.M., L.L. Smith, K. Kuppannan, X. Yang, and V.H. Wysocki. 2003. Peptide sequencing using a patchwork approach and surface-induced dissociation in sector-TOF and dual quadrupole mass spectrometers. Journal of the American Society of Mass Spectrometry 14: 1387-1401.
Breci, L.A., D.L. Tabb, J.R. Yates 3rd, and V.H. Wysocki. 2003. Cleavage N-terminal to proline: analysis of a database of peptide tandem mass spectra. Analytical Chemistry 75: 1963-1971.
Somogyi, A., D.L. Smith, V.H. Wysocki, R. Colorado Jr., and T.R. Lee. 2002. Neutralization of methyl cation via chemical reactions in low-energy ion-surface collisions with fluorocarbon and hydrocarbon self-assembled monolayer films. Journal of the American Society of Mass Spectrometry 13: 1151-1161.
Wysocki, V.H., G. Tsaprailis, L.L. Smith, and L.A. Breci. 2000. Mobile and localized protons: a framework for understanding peptide dissociation. Journal of Mass Spectrometry 35: 1399-1406.
Gu, C., G. Tsaprailis, L. Breci, and V.H. Wysocki. 2000. Selective gas phase cleavage at the peptide bond C-terminal to aspartic acid in fixed-charge derivatives of Asp-containing peptides. Analytical Chemistry 72: 5804-5813.
Angelico, V.J., S.A. Mitchell, and V.H. Wysocki. 2000. Low-energy ion-surface reactions of pyrazine with two classes of self-assembled monolayers: influence of alkyl chain orientation. Analytical Chemistry 72: 2603-2608.
