Thiol oxidation by haem peroxidases.
Abstract
The dominant role of thiols in biochemical detoxification processes ("repair" or "protective" properties) involves the intermediary formation of thiyl radicals, which themselves are known to be able to abstract hydrogen atoms from suitable activated C-H groups (prooxidative properties). The kinetics of production and the concentrations of potential reaction partners (molecular oxygen, thiolate, and phenols) determine the behaviour of thiyl radicals in aqueous solutions. The in vitro system peroxidase (horseradish peroxidase, lactoperoxidase, myeloperoxidase)/thiol offers the possibility to generate thiyl radicals from both aliphatic and aromatic thiols at defined rates determined by their ability to react with peroxidase intermediates compound I and II. Varying enzyme and/or thiol concentrations allows elucidation of the relationship of structure and reactivity of a large spectrum of thiols under comparable conditions. The present project should help to clarify the mechanism of thiol oxidation by both plant and human type peroxidases. Finally it should help to elucidate the mechanisms by which aliphatic and aromatic thiyl radicals are scavenged in aqueous systems by phenols, superoxide radicals and also thiols (thiolates) themselves. The aim of these in vitro studies is to introduce the system peroxidase/thiol as an enzyme based thiyl radical generator with known generation rates. It offers an alternative to the pulse radiolysis techniques (which so far gave the substantial part of knowledge of sulfur-centered radicals and their behaviour in aqueous solutions).
thiyl radicals
Publikationen
Monolignol oxidation and DHP-formation by HRP and purified wood isoenzymes from Fagus sylvatica.
Autoren: Furtmüller, P., Stelzer, D., Obinger, C., Ebermann, R. Jahr: 1996
Chapter in collected volumes
Transient-state and steady-state kinetics of the oxidation of aliphatic and aromatic thiols by horseradish peroxidase.
Autoren: Burner, U; Obinger, C Jahr: 1997
Journal articles
Generation of hydrogen peroxide by plant peroxidases mediated thiol oxidation.
Autoren: Obinger, C; Burner, U; Ebermann, R Jahr: 1997
Journal articles
Thiol oxidation by horseradish peroxidase: Hydrogen peroxide generation and the influence of phenols.
Autoren: Obinger, C., Burner, U., Vötsch, B., Hofstetter, W., Ebermann, R. Jahr: 1996
Chapter in collected volumes
Project staff
Christian Obinger
Univ.Prof. Mag.rer.nat. Dr.rer.nat. Christian Obinger
christian.obinger@boku.ac.at
Tel: +43 1 47654-10011, 77273
Project Leader
01.10.1995 - 28.02.1999