Energy and Entropy Effects in Dissociation of Peptide Radical Anions

Journal Article · Sun Apr 15 04:00:00 EDT 2012 · International Journal of Mass Spectrometry

DOI:https://doi.org/10.1016/j.ijms.2012.01.006· OSTI ID:1039836

Laskin, Julia; Yang, Zhibo; Lam, Corey; Chu, Ivan K

Time- and collision energy-resolved surface-induced dissociation (SID) of peptide radical anions was studied for the first time using a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) configured for SID experiments. Peptide radical cations and anions were produced by gas-phase fragmentation of CoIII(salen)-peptide complexes. The effect of the charge, radical, and the presence of a basic residue on the energetics and dynamics of dissociation of peptide ions was examined using RVYIHPF (1) and HVYIHPF (2) as model systems. Comparison of the survival curves for of [M+H]{sup +}, [M-H]{sup -}, M{sup +{sm_bullet}}, and [M-2H]{sup -{sm_bullet}} ions of these precursors demonstrated that even-electron ions are more stable towards fragmentation than their odd-electron counterparts. RRKM modeling of the experimental data demonstrated that the lower stability of the positive radicals is mainly attributed to lower dissociation thresholds while entropy effects are responsible the relative instability of the negative radicals. Substitution of arginine with less basic histidine residue has a strong destabilizing effect on the [M+H]{sup +} ions and a measurable stabilizing effect on the odd-electron ions. Lower threshold energies for dissociation of both positive and negative radicals of 1 are attributed to the presence of lower-energy dissociation pathways that are most likely promoted by the presence of the basic residue.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1039836
• Report Number(s): PNNL-SA-84641; 40004; 24494; KC0302020
• Journal Information: International Journal of Mass Spectrometry, Journal Name: International Journal of Mass Spectrometry Vol. 316-318
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
ANIONS
ARGININE
CATIONS
DISSOCIATION
ENTROPY
Environmental Molecular Sciences Laboratory
FRAGMENTATION
HISTIDINE
INSTABILITY
ION CYCLOTRON-RESONANCE
MASS SPECTROMETERS
PEPTIDES
RADICALS
RESIDUES
SIMULATION
STABILITY
SURVIVAL CURVES