Purification of cytochrome b-561 from bean hypocotyls plasma membrane. Evidence for the presence of two heme centers.
The high potential, ascorbate-reducible b-type cytochrome of plant plasma membranes, named cytochrome b-561, has been purified to homogeneity from etiolated bean hypocotyls. The pure protein migrated in denaturing electrophoresis as a broad band of approximately 55 kDa, and was found to be glycosylated. Optical redox titrations of partially purified cytochrome b-561 indicated that it contains two hemes with similar spectral features, but distinct midpoint redox potentials (E(m7)+135 mV and +206 mV, respectively). The presence of two heme centers in cytochrome b-561 is consistent with its role in electron transfer across plant plasma membranes.
Trost
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Department of Biology, University of Bologna, Via Irnerio 42, I-40126 Bologna, Italy. trost@alma.unibo.it
Bèrczi
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Sparla
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Sponza
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Marzadori
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Asard
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Pupillo
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D002462:Cell Membrane / Q000737:chemistry; D002852:Chromatography, Ion Exchange; D003573:Cytochrome b Group / Q000737:chemistry / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D007887:Fabaceae / Q000737:chemistry*; D006418:Heme / Q000737:chemistry; D018546:Hypocotyl / Q000737:chemistry; D010946:Plants, Medicinal; D011199:Potentiometry; D013053:Spectrophotometry
D003573:Cytochrome b Group; C023646:cytochrome b561; D006418:Heme