CYTOCHROMES FUNCTIONALLY ASSOCIATED TO PHOTOCHEMICAL-REACTION CENTERS IN RHODOPSEUDOMONAS-PALUSTRIS AND RHODOPSEUDOMONAS-ACIDOPHILA

作     者：MATSUURA, K SHIMADA, K 

作者机构：Department of Biology Faculty of Science Tokyo Metropolitan University Fukazawa 2-1-1 Setagaya-ku Tokyo 158 Japan 

出 版 物：《BIOCHIMICA ET BIOPHYSICA ACTA》 (Biochim. Biophys. Acta Bioenerg.)

年 卷 期：1986年第852卷第1期

页      面：9-18页

核心收录：

学科分类：0710[理学-生物学] 071010[理学-生物化学与分子生物学] 07[理学] 

主　　题：Bacterial photosynthesis Electron transfer Cytochrome c Reaction center ( Rps. palustris, Rps. acidophila ) BChl bacteriochlorophyll (BChl) + 2 oxidized bacteriochlorophyll dimer in reaction centers B-880 light-harvesting pigment-protein complex with an absorption peak of bacteriochlorophyll around 880 nm RC reaction center Q A primary quinone acceptor of reaction centers CCCP carbonyl cyanide m -chlorophenylhydrazone DAD 2,3,5,6-tetramethyl- p -phenylenediamine HNQ 2-hydroxynaphthoquinone PMS N -methylphenazonium methosulfate Mops 4-morpholinepropanesulfonic acid 

摘      要：Electron donors to photo-oxidized reaction centers were studied in Rhodopseudomonas palustris and R. acidophila using whole cells, membrane preparations and reaction center-B880 complexes. In Rps. palustris, no hemes were tightly bound to the reaction center complex and cytochrome c2 was presumed to be the direct electron donor to the photo-oxidized bacteriochlorophyll dimer in whole cells. Cytochrome c2 was lost in the membrane preparation obtained after a French press disruption of cells and mammalian cytochrome c added externally was oxidized by illumination. On the other hand, in Rps. acidophila, the reaction center complex was tightly associated with four cytochrome hemes, two of which were identified as cytochrome c-553 (Em7 = 110 mV) and the other two as cytochrome c-555 (Em7 = 110 mV) and the other two as cytochrome c-555 (Em7 = 360 mV). When both cytochromes were reduced prior to illumination, cytochrome c-553 was rapidly oxidized by a flash. Cytochrome c-555 was the one oxidized by a flash when cytochrome c-553 was already oxidized before activation. Cytochrome c2 was presumed to be the electron donor to the photo-oxidized cytochrome c-555 in whole cells. In the membrane preparation, a rapid electron transfer was observed from externally added mammalian cytochrome c to photooxidized cytochrome c-555. A possible phylogenetic correlation between the absence of the tightly bound cytochromes and a long class of cytochrome c2 (Dickerson, R.E. (1980) Nature 283, 210-212) is discussed.