Pharmaceutical Research

, Volume 12, Issue 3, pp 348–355

Chemical Pathways of Peptide Degradation. VIII. Oxidation of Methionine in Small Model Peptides by Prooxidant/Transition Metal Ion Systems: Influence of Selective Scavengers for Reactive Oxygen Intermediates

  • Shihong Li
  • Christian Schöneich
  • Ronald T. Borchardt
Article

DOI: 10.1023/A:1016240115675

Cite this article as:
Li, S., Schöneich, C. & Borchardt, R.T. Pharm Res (1995) 12: 348. doi:10.1023/A:1016240115675

Abstract

In the presence of oxygen, Fe(III), and an appropriate electron donor (e.g. ascorbic acid, dithiothreitol), the oxidation of methionine residues to methionine sulfoxides in small model peptides can be induced. It is shown in this study that these oxidations can be retarded by catalase in a pH-dependent manner, by some hydroxyl radical scavengers, and by azide. In contrast, superoxide dismutase has only a minimal effect, indicating that the superoxide radical does not contribute significantly to the oxidation of the methionine residue. The experimental results can be interpreted by invoking hydrogen peroxide as the major oxidizing species at pH ≤ 7, whereas the involvement of free hydroxyl radicals seems to be negligible. Other reactive oxygen intermediates such as iron-bound hydroperoxy, or site-specifically generated reactive oxygen species may be actively involved in the oxidation of methionine residues at pH > 7.

methionine methionine sulfoxide free radicals ascorbate dithiothreitol catalase superoxide dismutase 

Copyright information

© Plenum Publishing Corporation 1995

Authors and Affiliations

  • Shihong Li
    • 1
  • Christian Schöneich
    • 1
  • Ronald T. Borchardt
    • 1
  1. 1.Department of Pharmaceutical ChemistryThe University of KansasLawrence
  2. 2.Department of Pharmaceutical Chemistry, 3006 Malott Hall, School of PharmacyThe University of KansasLawrence

Personalised recommendations