Green algal cytochrome b6-f complexes: isolation and characterization from Dunaliella saline, Chlamydomonas reinhardtii and Scenedesmus obliquus.
Cytochrome b6-f complexes have been isolated from Chlamydomonas reinhardtii, Dunaliella saline and Scenedesmus obliquus. Each complex is essentially free of chlorophyll and carotenoids and contains cytochrome b6 and cytochrome f hemes in a 2:1 molar ratio. C. reinhardtii and S. obliquus complexes contain the Rieske iron-sulfur protein (present in approx 1:1 molar ratio to cytochrome f) and each catalyzes a DBMIB- and DNP-INT-sensitive electron transfer from duroquinol to spinach plastocyanin. Immunological assays using antibodies to the peptides from the spinach cytochrome complex show varying cross-reactivity patterns except for the complete absence of binding to the Rieske proteins in any of the three complexes, suggesting little structural similarity between the Rieske proteins of algae with those from higher plants. One complex (D. salina) has been uniformly labeled by growth in NaH14CO3 to determine stoichiometries of constituent polypeptide subunits. Results from these studies indicate that all functionally active cytochrome b6-f complexes contain four subunits which occur in equimolar amounts.
Division of Molecular Plant Biology, University of California, Berkeley 94720.
R M
RM
Wynn
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J
Bertsch
B D
BD
Bruce
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Malkin
D002696:Chlamydomonas / Q000032:analysis; D000460:Chlorophyta / Q000032:analysis*; D003573:Cytochrome b Group / Q000032:analysis* / Q000378:metabolism; D045346:Cytochrome b6f Complex; D003991:Dibromothymoquinone / Q000494:pharmacology; D004579:Electron Transport / Q000187:drug effects; D014450:Electron Transport Complex III; D004591:Electrophoresis, Polyacrylamide Gel; D006873:Hydroquinones / Q000378:metabolism; D007118:Immunoassay; D007506:Iron-Sulfur Proteins / Q000032:analysis; D007700:Kinetics; D010088:Oxidoreductases / Q000037:antagonists & inhibitors; D010455:Peptides / Q000032:analysis; D010970:Plastocyanin / Q000378:metabolism; D014301:Trinitrobenzenes / Q000494:pharmacology
D003573:Cytochrome b Group; D006873:Hydroquinones; D007506:Iron-Sulfur Proteins; D010455:Peptides; C037989:Rieske iron-sulfur protein; D014301:Trinitrobenzenes; D003991:Dibromothymoquinone; C026642:2-iodo-6-isopropyl-3-methyl-2',4,4'-trinitrodiphenyl ether; D010970:Plastocyanin; D045346:Cytochrome b6f Complex; D010088:Oxidoreductases; D014450:Electron Transport Complex III; C016421:duroquinol