| Studies on the DT-diaphorase-catalysed reaction employing quinones as substrates: evidence for a covalent modification of DT-diaphorase by tetrachloro-p-benzoquinone. | |
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MedLine Citation:
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PMID: 14726156 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In this study, the kinetic parameters, V(max) and K(m), 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 V(max)/K(m) 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-benzoquinone 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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Authors:
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Ahmed M Osman; Sjef Boeren |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Chemico-biological interactions Volume: 147 ISSN: 0009-2797 ISO Abbreviation: Chem. Biol. Interact. Publication Date: 2004 Jan |
Date Detail:
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Created Date: 2004-01-16 Completed Date: 2004-03-04 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0227276 Medline TA: Chem Biol Interact Country: Ireland |
Other Details:
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Languages: eng Pagination: 99-108 Citation Subset: IM |
Affiliation:
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Institute for Inland Water Management and Waste-water Treatment, P.O. Box 17, 8200 AA Lelystad, The Netherlands. a.osman@riza.rws.minvenw.nl |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Benzoquinones / chemistry, metabolism*, pharmacology* Catalysis / drug effects Cattle Hydrophobicity Kinetics Liver / enzymology NAD(P)H Dehydrogenase (Quinone) / isolation & purification, metabolism* Rats Serum Albumin, Bovine / metabolism Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization Structure-Activity Relationship Substrate Specificity |
| Chemical | |
Reg. No./Substance:
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0/Benzoquinones; 0/Serum Albumin, Bovine; EC 1.6.5.2/NAD(P)H Dehydrogenase (Quinone) |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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