Ionization energies of multiply protonated polypeptides obtained by tandem ionization in Fourier transform mass spectrometers
Article first published online: 7 NOV 2002
Copyright © 2002 John Wiley & Sons, Ltd.
Journal of Mass Spectrometry
Volume 37, Issue 11, pages 1141–1144, November 2002
How to Cite
Budnik, B. A., Tsybin, Y. O., Håkansson, P. and Zubarev, R. A. (2002), Ionization energies of multiply protonated polypeptides obtained by tandem ionization in Fourier transform mass spectrometers. J. Mass Spectrom., 37: 1141–1144. doi: 10.1002/jms.376
- Issue published online: 7 NOV 2002
- Article first published online: 7 NOV 2002
- Manuscript Accepted: 6 SEP 2002
- Manuscript Received: 5 FEB 2002
- Danish National Research Foundation. Grant Number: 9801448.
- Swedish Natural Research Council.
- ionization energy;
- odd-electron ions;
- electron impact;
- fourier transform ion cyclotron resonance
Ionization energies (IE) of [M + zH]z+ (z+) electrospray-produced polypeptides were determined by electron ionization in a Penning cell of 4.7 and 9.4 T Fourier transform mass spectrometers. For z = 1+ and substance P, the found IE value of 11.0 ± 0.4 eV is in agreement with that obtained earlier for ions generated with matrix-assisted laser desorption/ionization. For higher z, the following values were found: 11.7 ± 0.3 eV for 2+ of [Arg-8]-vasopressin, 11.1 ± 0.6 eV for 2+ of substance P, 12.2 ± 0.7 eV for 2+ of renin substrate, 13.3 ± 0.4 eV for 3+ of B-chain of insulin and 14.6 ± 0.6 eV for 4+ and 15.1 ± 0.4 eV for 5+ of melittin. It was found that 90% of existing IE data on polypeptides in the 1.0–3.5 kDa mass range are described with ≤0.5 eV uncertainty by the empirical equation IE(z) = 9.8 + 1.1z. The average IE increase of 1.1 eV/charge is attributed to Coulombic repulsion. The deduced ionization energy of a neutral polypeptide molecule, 9.8 ± 0.3 eV, is consistent with literature expectations. Copyright © 2002 John Wiley & Sons, Ltd.