Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (10): 2772-2778.doi: 10.3866/PKU.WHXB20101004


Characteristics of One Electron Redox Behavior of Hydrophobic AminoAcids in Gas Phase

LI Wei-Wei, HOU Ruo-Bing, SUN Yan-Li   

  1. College of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin 541004, Guangxi Province, P. R. China
  • Received:2010-05-26 Revised:2010-06-30 Published:2010-09-27
  • Contact: HOU Ruo-Bing
  • Supported by:

    The project was supported by the Innovation Project of Guangxi Graduate Education, China (2009106020703M48).


Characteristics of the one electron redox behavior of hydrophobic amino acids in gas phase were calculated with density functional theory at the B3LYP/DZP++ level. For glycine, alanine, proline, valine, leucine, and isoleucine with small side chains, the computational results indicate that the negative charges are removed from the atoms of their amino, α-carbon, and carboxy moieties in one electron oxidation reactions. This yields large adiabatic ionization potentials (AIP) of 8.52-9.15 eV. The AIPs of cysteine, methionine, phenylalanine, tyrosine, and tryptophan decrease because of the larger amount of negative charge removed from the atoms in their side chains. The attachment of one electron to the molecules of hydrophobic amino acids leads to anions in which the extra electron is bound to the H atoms of the carboxyl or amino groups and to their valence orbitals, reflecting the double nature of the dipole -bound state and the valence state. The electron affinities (EA) for the amino acids are small and negative ranging from -0.08 to -0.63 eV. The molecules of the hydrophobic amino acids are oxidized or reduced with difficulty in gas phase because of their high VIPs and negative EAs.

Key words: Hydrophobic amino acid, Ionization potential, Electron affinitiy, Redox


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