Search results for "Electron-capture dissociation"
showing 3 items of 3 documents
Two- and three-state conical intersections in the electron capture dissociation of disulfides: The importance of multireference calculations
2011
The SS bond cleavage produced upon electron attachment to disulfides was generally assumed to be an adiabatic process because the added electron occupies the σ*(SS) antibonding orbital. This is clearly the case in the parent HSSH compound, but not necessarily in XSSX′ derivatives, where the substituents X and X′ are different. Through the use of MS-CASPT2 calculations, we have shown that the dissociation of the SS two-center-three-electron bond in these asymmetric XSSX′ compounds requires the interaction of at least two states, in order to localize the extra electron in one of the fragments upon dissociation. This is actually the case for the CH3SSNH2 derivative, where the most favorable di…
ETD and ECD Mass Spectrometry Fragmentation for the Characterization of Protein Post Translational Modifications
2012
The introduction of electron capture dissociation (ECD) by McLafferty and co-workers, and further of electron transfer dissociation (ETD), mechanism allows gas-phase fragmentation of multiply charged protein and peptide ions upon capture of a low-energy (<1 eV) electron or electron transfer in a gas phase ion-ion chemistry. The odd-electron species then undergoes rearrangement with subsequent cleavage of N−Cα backbone. Peptide fragmentation can take place inducing the formation of cand ztype fragment ions without loss of the information on the PTM localization. The key to the success of this approach is the selection of intact protein molecular ions and its profound potential for PTM charac…
Noncovalent Saccharide Recognition by Means of a Tetrakis(bile acid)-Porphyrin Conjugate: Selectivity, Cooperation, and Stability
2010
Molecular recognition of Glu, Glc 2 -Glc 6 and Mal 3 by a tetrakis(bile acid)―porphyrin conjugate has been studied by using ESI-FTICR mass spectrometry. The bile acid conjugate was observed to form 1:1 noncovalent complexes with saccharides. The conjugate was found to have size-selectivity towards saccharides with three or more glucose residues. The Glc 3 and Glc 4 also formed kinetically the most stable complexes. The electron capture dissociation (ECD) experiments revealed that in complexation of an oligosaccharide three glucose residues interact with the bile acid conjugate, whereas additional glucose residues are susceptible to fragmentation. The ECD results also showed the significance…