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Effectors of the mammalian plasma membrane NADH-oxidoreductase system. Short-chain ubiquinone analogues as potent stimulators
Vaillant, Francois Larm, Jari McMullen, Gabrielle Wolvetang, Ernst Lawen, Alfons
Vaillant, Francois
Larm, Jari
McMullen, Gabrielle
Wolvetang, Ernst
Lawen, Alfons
Abstract
In the presence of effectors variations in the two recognized activities of the plasma membrane NADH-oxidoreductase system were studied in separate, specificin vitro assays. We report here that ubiquinone analogues that contain a short, less hydrophobic side chain than coenzyme Q-10 dramatically stimulate the NADH-oxidase activity of isolated rat liver plasma membranes whereas they show no effect on the reductase activity of isolated membranes. If measured in assays of the NADH∶ferricyanide reductase of living cultured cells these compounds have only a limited effect; the oxidase activity of whole cells is not measurable in our hands. We have furthermore identified selective inhibitors of both enzyme activities. In particular, the NADH-oxidase activity can be significantly inhibited by structural analogues of ubiquinone, such as capsaicin and resiniferatoxin. The NADH∶ferricyanide reductase, on the other hand, is particularly sensitive to pCMBS, indicating the presence of a sulfhydryl group or groups at its active site. The identification of these specific effectors of the different enzyme activities of the PMOR yields further insights into the function of this system.
Keywords
Plasma membrane NADH-oxidoreductase, NADH-oxidase, NADH∶ferricyanide reductase, ubiquinone analogues, ρ0 cells
Date
1996
Type
Journal article
Journal
Journal of Bioenergetics and Biomembranes
Book
Volume
28
Issue
6
Page Range
531-540
Article Number
ACU Department
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Open Access Status
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Controlled