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Developing of a suicide inhibitors for human myeloperoxidase

Project management Obinger Christian
organizational unit Institute of Biochemistry
duration 01.08.2000 to- 31.07.2003
Research project (§ 26 & § 27)
Program none
Funder Austrian Science Fund (FWF)
Competencies 

    Abstract

    Myeloperoxidase (MPO) is the most abundant protein in neutrophils and catalyzes the production of hypochlorous acid. This potent oxidant plays a central role in microbial killing. But there is evidence in the literature that neutrophils contribute also to many inflammatory pathologies (e.g. rheumatoid arthritis, cystic fibrosis, asthma etc.). A specific and potent inhibitor of myeloperoxidase would be a useful tool for probing the role of the enzyme in neutrophil-mediated inflammatory tissue damage and microbial killing, as well as for providing valuable information on its mechanism of action. Moreover, attenuation of neutrophil function by pharmacological intervention has considerable therapeutic potential. It is desireable to design drugs that will dampen inflammation without precipitating infectious diseases.We have recently shown that hydrazides and hydroquinones are potent suicide substrates which trap the enzyme in an inactive form and finally, irreversibly inactivate it by destruction of its heme prosthetic groups. This approach will be followed in this project by extending this work with substrate analogues and determination of the reactions that are involved in the proposed mechanism-based inhibition pathway. The key reaction in this mechanism is reduction of the ferric enzyme to the ferrous form by radicals produced by MPO intermediates compound I and II. Ferrous MPO either reacts with oxygen forming compound III or with hydrogen peroxide and/or with the inhibitor or its oxidation product leading to heme destruction. The reactions involved are less understood and should be investigated in this project. Since the reduction potential of the couple ferric-MPO/ferrous-MPO is relatively high in comparison to other heme peroxidases, this feature is exploited to design specific MPO inhibitors. We develop substrate analogues (AH2) in order to proof the influence of substitution on the efficiency of ferrous MPO formation, binding to the active site of MPO and on prevention of hypochlorous acid formation. The influence of substitution on the redox potential of the couple AH*/AH2 and on the radical generation rate by both compound I and compound II has to be tested. We intend to analyze the products of oxidation of the substrate analogues as well as the modifications at the active site of myeloperoxidase. The selected inhibitors will be tested in in vitro models known to involve MPO mediated hypochlorous acid formation as well as in vivo by elucidating their influence on hypochlorous acid formation and bacterial killing by neutrophils.

    Publications

    Project staff

    Portrait Christian Obinger

    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

    01.08.2000 - 31.07.2003

    Portrait Paul Georg Furtmüller

    Paul Georg Furtmüller

    ao.Univ.Prof. Dipl.-Ing.Dr.nat.techn. Paul Georg Furtmüller
    paul.furtmueller@boku.ac.at
    Tel: +43 1 47654-77277

    Project Staff

    01.08.2000 - 31.07.2003

    Portrait Walter Jantschko

    Walter Jantschko

    Dipl.-Ing. Walter Jantschko

    Project Staff

    01.08.2000 - 31.07.2003

    Portrait Florian Rüker

    Florian Rüker

    Ao.Univ.-Prof.i.R. Dr. Florian Rüker
    florian.rueker@boku.ac.at
    Tel: +43 1 47654-79854

    Project Staff

    01.08.2000 - 31.07.2003

    External partners

    University of Brussels, Applied Genetics

    Dr. Nicole Moguilevsky

    partner