Transmembrane electron transport in ascorbate-loaded plasma membrane vesicles from higher plants involves a b-type cytochrome.
The possible involvement of a high-potential b-type cytochrome in plasma membrane electron transport was tested using ascorbate-loaded membrane vesicles. Absorption spectra demonstrated that the cytochrome was about 89% reduced in these preparations. Use of ascorbate oxidase and washing of the vesicles further indicated that reduction was mediated by intra-vesicular ascorbate. Addition of low concentrations of ferricyanide caused a rapid cytochrome oxidation followed by a slower re-reduction. The kinetics of this response indicate that the electron acceptor was fully reduced before re-reduction of the cytochrome occurred. These observations suggest that the b-type cytochrome mediates transmembrane electron transfer.
Asard
H
H
Department of Biology, University of Antwerp RUCA, Belgium.
Horemans
N
N
Caubergs
R J
RJ
D001205:Ascorbic Acid / Q000378:metabolism*; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism*; D003573:Cytochrome b Group / Q000378:metabolism*; D004579:Electron Transport; D007887:Fabaceae / Q000201:enzymology*; D066298:In Vitro Techniques; D007700:Kinetics; D010946:Plants, Medicinal; D013057:Spectrum Analysis
D003573:Cytochrome b Group; C023646:cytochrome b561; D001205:Ascorbic Acid