Energetics, Dynamics and Mechanisms of Dissociation of Peptide Radical Cations
EMSL Project ID
24494
Abstract
This proposal is a continuation of research under EMSL User Proposal #14395. Peptide radicals play important roles in chemistry and biology. Fundamental studies of gas-phase reactivity of odd-electron peptide ions provides important information on the intrinsic properties of these species and enables the development of improved approaches for identification of biological molecules using mass spectrometry. ESI and MALDI are routinely used to introduce peptides and proteins into the gas phase in the form of closed-shell protonated ions. However, until recently formation of peptide radical cations in the gas phase was tedious and could be performed only for selected species. Formation of hydrogen-rich radical cations, [M+nH] • (n-1)+ , by capture of low-energy electrons results in electron capture dissociation (ECD). ECD is very attractive because it provides dissociation patterns that are complementary to CID. It has been demonstrated that ECD is superior to CID for top-down characterization of proteins. While dissociation of hydrogen-rich radical cations has been extensively studied, little is known about fragmentation behaviour of M +• ions and peptide radical anions. We will compare the stability of peptide radical cations and anions to the stability of the corresponding protonated and deprotonated species. Specifically we will address the following questions: Is the energetics of dissociation of these species similar to the dissociation energetics of smaller radical cations? Does conformational flexibility of these molecules have an effect on their gas phase stability? How significant are entropy effects? Does "mobile proton" affect dissociation of odd-electron peptide ions? Can we distinguish between radical-driven and proton-driven fragmentation pathways? Can complementary structural information be obtained from dissociation patterns of odd-electron hydrogen deficient biological ions?
Project Details
Project type
Large-Scale EMSL Research
Start Date
2007-06-01
End Date
2010-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
1. Song, T., Lam, C.N.W., Ng, D.C.M., Orlova, G., Laskin, J., Fang, D.C. & Chu, I.K. Experimental and Computational Studies of the Macrocyclic Effect of an Auxiliary Ligand on Electron and Proton Transfers Within Ternary Copper(II)-Histidine Complexes. J. Am. Soc. Mass Spectrom. 20, 972-984 (2009).
Chu IK, J Zhao, M Xu, SO Siu, AC Hopkinson, and KWM Siu . 2008. "Are the Radical Centers in Peptide Radical Cations Mobile? The Generation, Tautomerism, and Dissociation of Isomeric r-Carbon-Centered Triglycine Radical Cations in the Gas Phase." Journal of the American Chemical Society 130:7862–7872. doi:10.1021/ja801108j
J. Laskin, J. H. Futrell, I.K Chu, “Is Dissociation of Peptide Radical Cations an Ergodic Process?” J. Am. Chem. Soc., 2007, 129, 9598-9599
Laskin J, Z Yang, and IK Chu. 2008. "Energetics and Dynamics of Electron Transfer and Proton Transfer in Dissociation of Metal III (salen)-Peptide Complexes in the Gas Phase." Journal of the American Chemical Society 130(10):3218-3230. doi:10.1021/ja077690s
Laskin J, Z Yang, C Lam, and IK Chu. 2012. "Energy and Entropy Effects in Dissociation of Peptide Radical Anions." International Journal of Mass Spectrometry 316-318:251-258. doi:10.1016/j.ijms.2012.01.006
Laskin J, Z Yang, DC Ng, and IK Chu. 2010. "Fragmentation of alpha-Radical Cations of Arginine-Containing Peptides." Journal of the American Society for Mass Spectrometry 21(4):511-521. doi:10.1016/j.jasms.2009.12.021
Ng DC, T Song, SO Siu, CK Siu, J Laskin, and IK Chu. 2010. "Formation, isomerization, and dissociation of alpha-carbon-centered and pi-centered glycylglycyltryptophan radical cations." Journal of Physical Chemistry B 114(6):2270-2280. doi:10.1021/jp908599a
Siu, C.K., Zhao, J.F., Laskin, J., Chu, I.K., Hopkinson, A.C. & Siu, K.W.M. Kinetics for Tautomerizations and Dissociations of Triglycine Radical Cations. J. Am. Soc. Mass Spectrom. 20, 996-1005 (2009).
Song T, IK Chu, CK Siu, and J Laskin. 2012. "Mechanistic Examination of C?–C? Bond Cleavages of Tryptophan Residues during Dissociations of Molecular Peptide Radical Cations." PNNL-SA-87221, Pacific Northwest National Laboratory, Richland, WA.
Yang Z, C Lam, IK Chu, and J Laskin. 2008. "The Effect of the Secondary Structure on Dissociation of Peptide Radical Cations: Fragmentation of Angiotensin III and Its Analogues." Journal of Physical Chemistry B 112(39):12468-12478. doi:10.1021/jp805226x