A comparison of electron transport and photophosphorylation systems of Rhodopseudomonas capsulata and Rhodospirillum rubrum |
| |
Authors: | Zippora Gromet-Elhanan Howard Gest |
| |
Affiliation: | (1) Department of Biochemistry, The Weizmann Institute of Science, Rehovot, Israel;(2) Photosynthetic Bacteria Group, Department of Microbiology, Indiana University, 47401 Bloomington, IN, USA |
| |
Abstract: | The photophosphorylation systems of Rhodopseudomonas capsulata and Rhodospirillum rubrum chromatophores have been compared in respect to the effects of artificial electron carries [N-methyl-phenazonium methosulfate (PMS) and diaminodurene], reducing agents (ascorbate in particular), and various quinones in the absence and presence of the electron transport inhibitors antimycin A and dibromothymoquinone (DBMIB). In addition, the effects of both inhibitors on photosynthetic electron transport through cytochromes b and c has been followed. From the results obtained, it appears that in both organisms: a) ubiquinone functions as an electron carrier between the cytochromes, and b) both antimycin A and DBMIB inhibit cyclic electron flow in the segment ... cytochrome bubiquinone»cytochrome c ..., but at different sites. The systems apparently differ mainly in respect to the nature of the electron flow by-pass shunt that is evoked in the presence of PMS; thus, in R. rubrum, PMS catalyzes a shunt that by-passes both cytochrome b and ubiquinone, whereas in Rps. capsulata the PMS shunt seems to circumvent only ubiquinone.Abbreviations BChl bacteriochlorophyll - DAD diaminodurene=2,3,5,6-tetramethyl-p-phenylenediamine - DBMIB dibromothymoquinone=2,5-dibromo-6-isopropyl-3-methylbenzoquinone - HOQNO heptylhydroxyquinoline-N-oxide - PMS N-methylphenazonium methosulfate |
| |
Keywords: | Rhodospirillum rubrum Rhodopseudomonas capsulata Chromatophores Photophosphorylation Electron transport Ubiquinone Cytochromes Dibromothymoquinone Antimycin A |
本文献已被 SpringerLink 等数据库收录! |
|