Temporary anion states of selected amino acids

Authors

Kayvan Aflatooni, University of Nebraska-LincolnFollow
B. Hitt, University of Nebraska-Lincoln
Gordon A. Gallup, University of Nebraska-LincolnFollow
Paul Burrow, University of Nebraska-LincolnFollow

Date of this Version

10-8-2001

Comments

Published by American Institute of Physics. J. Chem. Phys. 115, 6489 (2001). © 2001 American Institute of Physics. Permission to use. http://jcp.aip.org/.

Abstract

Vertical attachment energies for the formation of low-lying temporary anion states of glycine, alanine, phenylalanine, tryptophan, and proline in the gas phase are reported using electron transmission spectroscopy. Electron attachment into the empty π* orbital of the –COOH group was observed in all the compounds. Temporary anion states associated with the side groups in phenylalanine and tryptophan are found to be stabilized with respect to those in the reference compounds toluene and indole, respectively, by approximately 0.2 eV. We attribute this to electrostatic effects and explore, using simple theoretical models, the extent to which such anion states could be further stabilized if these amino acids were in zwitterionic form.