Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Studies on the DT-diaphorase-catalysed reaction employing quinones as substrates: evidence for a covalent modification of DT-diaphorase by tetrachloro-p-benzoquinone
    Osman, A.M. ; Boeren, J.A. - \ 2004
    Chemico-Biological Interactions 147 (2004)1. - ISSN 0009-2797 - p. 99 - 108.
    one-electron - rat-liver - acceptor oxidoreductase - mechanism - reductase - nitrobenzimidazoles - cytotoxicity - conversion - protein - nad(p)h
    In this study, the kinetic parameters, Vmax and Km, of rat liver DT-diaphorase were determined for a series of p-benzoquinones, with methyl, methoxy, cyano, hydroxy and halo substituents. The results show that there is no correlation between the experimentally determined rates of p-benzoquinone reduction by DT-diaphorase and the calculated chemical reactivity of the examined substrates as expressed by the energy of the lowest unoccupied molecular orbital, E(LUMO). However, a reasonable correlation was found between the natural logarithm of Vmax/Km and the partition coefficient of the p-benzoquinones (r=0.81). Furthermore, tetrachloro-p-benzoquinone, one of the tested quinones is shown to be an inhibitor of rat DT-diaphorase. The presence of bovine serum albumin (BSA) in the incubation mixture protects DT-diaphorase against the inactivation by tetrachloro-p-benzoquinone, probably by interacting with the quinone. Maldi-Tof analysis of the incubation mixture of the purified DT-diaphorase and tetrachloro-p-benquinone showed that every subunit of the enzyme shifted about +414 amu, whereas the dimer shifted about +849 amu relative to control values. This indicates a covalent modification of the rat liver DT-diaphorase by tetrachloro-p-benzoquinone.
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