|
| CURRENT EVENTS |
CRMS LECTURE SERIES SCHEDULE – 2007/08
Seminars were held every other Wednesday afternoon from 12:30 – 1:30 pm in the Petrie lounge (room PSE 315).
| January 9th |
Dr. Julia Laskin – Pacific Northwest National Laboratory |
Ion-Surface Collisions in FT-ICR Mass Spectrometry |
Ion-surface collisions are utilized in materials science, mass spectrometry, imaging and spectroscopy. Our research is focused on fundamental understanding of interaction of hyperthermal (1-100 eV) peptide, protein and polymer ions with organic surfaces under ultrahigh vacuum conditions. Two major processes are dominant for this range of collision energies: reactive and non-reactive scattering of ions and ion loss on the surface as a result of neutralization or soft-landing (SL) of projectile ions. Ion activation by collisions with a specially prepared surface followed by surface-induced dissociation (SID) of vibrationally excited ions offers unique advantages both for analytical applications and for fundamental studies of gas-phase fragmentation of complex ions. Coupling surface-induced dissociation (SID) with a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FT-ICR MS) both greatly reduces the kinetic shift and allows us to access the lowest-energy dissociation pathways for large molecules. We demonstrated that a proper choice of the SID target dramatically enhances sequence-specific fragmentation in MS/MS spectra and improves identification of peptides that cannot be identified using conventional ion activation techniques. In situ FT-ICR SIMS characterization of surfaces following SL allowed us to conduct systematic studies of factors that affect the SL efficiency and the evolution of different charge states of soft-landed peptide ions on SAM surfaces. We obtained unique kinetics signatures for different charge states of soft-landed species retained on the surface and rationalized our results using a simple kinetic model that takes into account charge reduction and thermal desorption of different species from the surface.
|
| January 30th |
Guerman Pasmanik – Passat Ltd. |
Diode-pumped nano- and picosecond solid-state lasers, custom lasers and laser systems |
Bio-med and nanotechnologies.
MALDI lasers especially with a fibre output (narrow dia 50-um, 100-um for high resolution in the sampling procedure);
Combining of 3-um nanosecond and 355-nm picosecond pulses for IR MALDI;
Laser ablation and destruction in the field of picosecond pulses;
Si-wafer modification for Mass Spectrometry needs;
Etching, trimming and cutting of plastics with min collateral damage;
New approach to photo-lithography and its comparing with traditional methods;
Two photon microscopy;
Glass modification by 213-nm picosecond pulses.
Remote sensing
Eye-safe picosecond turnkey lasers for urban profiling, vehicle collision avoidance,security zone monitoring;
Picosecond lasers for precise ranging, tracking, 3D mapping;
Picosecond upgrade of Local and Global Positioning Systems;
Lasers for search of natural resources;
Explosive detection with high sensetivity.
|
| February 27th |
John Eliades – University of Toronto |
|
Accelerator Mass Spectrometry (AMS) typically involves the use of a 1-6 MV tandem accelerator to perform mass spectrometry with very low background. It was developed in the 1970's as a means of performing sensitive measurements to do carbon dating and the field quickly grew to include analyses of other trace radio-isotopes. While AMS has proven to work exceedingly well for some isotopes, the analysis of others is still hampered by interferences from atomic isobars. At IsoTrace Lab we are working on a new solution whereby a reaction cell is used to remove the isobaric interference from the ion beam at low energy by taking advantage of gas-phase chemical reactions before the beam is introduced to the accelerator for analysis. In this talk I will introduce the general principles of AMS, discuss some of its applications to environmental samples and then go over the apparatus that we are building and testing at IsoTrace.
|
| March 12th (PSE 317) |
Dr. Junfang Zhao – York University |
Are the Radical Centers in Peptide Radical Cations Mobile? The Generation, Tautomerism, and Dissociation of Three Isomeric Triglycine Radical Cations in the Gas Phase? |
The mobility of the radical center in three isomeric triglycine radical cations [GdotGG]+, [GGdotG]+, and [GGGdot]+ has been investigated theoretically via density functional theory (DFT) and experimentally via tandem mass spectrometry. These radical cations were generated by collision-induced dissociations (CIDs) of Cu(II)-containing tertiary complexes that contain the tripeptides YGG, GYG, and GGY, respectively. Dissociative electron transfer of the complexes led to observation of [YdotGG]+, [GYdotG]+, and [GGYdot]+. CID resulted in cleavage of the tyrosine side chain as quinomethide yielding [GdotGG]+, [GGdotG]+, and [GGGdot]+, respectively. DFT calculations showed that interconversions between these isomeric triglycine radical cations have relatively high barriers (45-50 kcal/mol) in support of the thesis that isomerically pure [GdotGG]+, [GGdotG]+, and [GGGdot]+ can be experimentally produced. This is to be contrasted with barriers < 17 kcal/mol that were encountered in the tautomerism of protonated triglycine [Rodriquez C.F. et al. J. Am. Chem. Soc. 2001, 123, 3006-3012]. The CID spectra of [GdotGG]+, [GGdotG]+, and [GGGdot]+ were substantially different, providing experimental proof that initially these ions have distinct structures. DFT calculations showed that direct dissociations are competitive with interconversions followed by dissociation.
|
| March 26th |
Jim Kepka, Midwest Sales Director – MesoScale Discovery |
See flyer for presentation overview |
| |
| April 9th (PSE 317) |
Dr. Voislav Blagojevic– York University |
Mass spectrometric study of interaction of Group XI metal cations with fatty acids: Ag2H+ as a double bond marker |
Study of complexation of Group XI cations (Cu+, Ag+ and Au+) with four fatty acids with varying degrees of unsaturation is presented here. The most interesting aspect of this work is almost exclusive formation of Ag2H+ when dissociating clusters containing more than one silver ion with unsaturated fatty acids. The Ag2H+ ion acts as an effective marker for the presence of the double bond in fatty acids. Neither Cu+ or Au+ show similar behaviour, fatty acid ligand fragmentation being preferred here.
|
| April 23rd |
Ayman El Faramawy – York University |
IRMPD on non-covalent complexes in a QqTOF mass spectrometer |
Proper understanding of the function and structure of protein complexes, and of disease related changes in such complexes, requires knowledge about the subunit stoichiometry. NanoESI often results MW determinations that are too high due to the presence of solvent and/or buffer adducts. Solvent adducts can be difficult to remove with the usual declustering fields and heated MS interfaces. We have interfaced an infrared laser to the collision cell of a QqTOF system in order to apply IRMPD to non-covalent complexes to allow the controllable removal of adducts from the complexes. IRMPD can also be used to fragment large non-covalent complexes.
|
| September 19th |
Prof. Derek Wilson – York University |
New MS and NMR Approaches for the Investigation of Protein Dynamics, Structure and Function |
Abstract:
The predominant tools of structural biology, while providing beautifully high resolution 'snapshots' of the lowest energy (or most readily crystallizable) protein conformation, offer only very limited dynamic information. Since critical elements of protein function are inherently dynamic (i.e. ligand binding/release, conformation changes, bond vibrations), it follows that a thorough understanding of the dynamic modes available to particular proteins is required to accurately predict their functional characteristics. The overriding objective of our research is to develop and apply new MS and NMR approaches for the investigation of dynamic processes in proteins. Where possible, time-resolved ESI-MS and biophysical NMR methods are applied to systems of interest in a complimentary fashion, facilitating exceptionally thorough descriptions of the target dynamics.
These new MS and NMR approaches will be introduced and their capability to provide insights into the dynamics underlying activity in a number of enzyme systems, as well as folding/amyloidosis in an Acylphosphatase (Sso-AcP), will be demonstrated. This highly multidisciplinary research draws on tools from molecular biology, analytical biochemistry and microfluidics.
|
| October 3rd |
Janeen Auld – York University |
Smog Chamber Studies: Analysis of beta-Pinene Photo-oxidation Products using Mass Spectrometry |
The hydroxyl radical initiated oxidation of hydrocarbons in the atmosphere produces a diverse range of organic products, which depending on their vapour pressures, may be found in the gas, and/or particle phase. Particles have been linked to having adverse effects on climate (ex. reduced visibility) and human health therefore making knowledge regarding their composition extremely valuable. However, even the identities of the gas phase secondary organic products are not well known. We are using the York University smog chamber and a triple quadrupole mass spectrometer to investigate the products formed via hydroxyl radical initiated photo-oxidation of beta-Pinene under varied NOx concentrations with the desire to improve the current understanding of product composition and formation mechanisms. An overview of the project will be presented with a focus on two identified products oxo-pinaketone and hydroxy-pinaketone. While these products have been previously identified their formation mechanisms have not been directly supported by experimental evidence. Results showing the effect of NOx on the formation of these products and the correlation to current formation mechanisms will be presented.
|
| October 17th |
Yuzhu Guo – York University |
Gas-Phase Ions Studied by Combined Mass Spectrometry and Ion Mobility Spectrometry |
Ion mobility spectrometry has proven to provide supplementary information on gas phase ions’ conformation, thus adding another dimension of separation in addition to m/z separation by mass spectrometry. A summary of some aspects of its application in separation methods and conformational probes, which has been obtained from the ion mobility spectrometer at York University, will be presented.
|
| October 31st |
Dr. Ali Shayesteh – York University |
High resolution infrared emission spectroscopy of gaseous metal hydrides |
Metal hydrides are among the simplest inorganic molecules. Ab initio theoretical calculations can predict reliable molecular parameters for small metal hydrides, and high quality experimental data on these molecules serve as benchmarks for testing the accuracy of ab initio methods. Several hydrides of Group 2 and 12 elements were generated in the gas phase using an emission source that combines an electrical discharge with a high temperature furnace, and their high-resolution infrared emission spectra were recorded with a Fourier transform spectrometer. Two classes of molecules were studied:
a) diatomic metal hydrides BeH, MgH, CaH, SrH, ZnH and CdH;
b) linear triatomic metal hydrides BeH2, MgH2, ZnH2 and HgH2.
Analyses of high-resolution infrared emission spectra yielded accurate experimental values for vibrational frequencies, rotational constants, metal-hydrogen bond distances, and Born-Oppenheimer breakdown correction parameters.
|
| November 14th |
Prof. Gerold Schmitt-Ulms – University of Toronto |
Proteomics meets neurodegeneration - concepts, tools and their application in search for rationale treatment strategies |
The seminar will describe research at the intersection of proteomics/mass spectrometry and its application to neurodegenerative disease. More specifically, Prof. Gerold Schmitt-Ulms will discuss:
1) the use of chemical crosslinking as a means to identify therapeutic targets in neurological disease
2) the development of a sensitive methodology for the elucidation of the molecular architecture of protein complexes.
|
| November 28th |
Michael Jarvis – York University |
|
We have undertaken a comprehensive study of the reactivity of a neutral reagent, dimethyldisulfide, towards ions of different classes and containing a variety of structural features. The purpose of this work is to determine the selectivity of ion-molecule reactions of this reagent, in order to assess its potential for chemically removing undesirable MS impurity ions. A method has been proposed that will employ ion-molecule chemistry and tandem mass spectrometry to filter out all reactive ions from a sample, prior to subsequent sample analysis. For this technique to be of practical use in the laboratory environment, the neutral reagent (dimethyldisulfide) must exhibit a high reactivity towards chemical impurity ions and a low reactivity towards MS analytes. In this work we have measured the reaction kinetics of dimethyldisulfide towards a host of common chemical impurity ions and model MS analytes using a Selected-Ion Flow Tube tandem mass spectrometer, at 0.35 Torr and 295 K. The results demonstrate that the proposed method is effective at removing many chemical background ions without interfering with the analysis of MS analytes.
|
| December 10th |
Prof. Chris Le – University of Alberta |
Arsenic interaction with proteins |
An investigation into the differences in arsenic-protein complexes as a detoxifying interaction in rats and humans.
|
| December 12th |
Prof. Rob Dunbar – Case Western Reserve University |
Some IR spectroscopic studies of gas-phase ions at the FELIX free electron laser |
The broadband tunable free electron light source, combined with the FT-ICR mass spectrometer, gives a rather new and powerful approach to doing IR spectroscopy of gas-phase ions. The FELIX group at the FOM Institute has been using this approach for structure studies of various complexes of metal ions with amino acids, dipeptides and proteins, as well as smaller model ligands having interesting basic sites for ion attachment. Competition among different binding sites on the ligand, and also effects of varying the nature of the metal ion, can be explored incisively with this technique.
|
|
|
