Open AccessThe Isolation and Characterization of a Photochemically Active Complex from Chloropseudomonas ethylica
Author(s) -
Charles F. Fowler,
N. A. Nugent,
R. C. Fuller
Publication year - 1971
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.68.9.2278
Subject(s) - bacteriochlorophyll , photosynthetic reaction centre , photosynthesis , chlorophyll , cytochrome , chemistry , redox , photochemistry , chlorosome , chlorophyll a , biochemistry , organic chemistry , enzyme
A photochemically active subcellular fraction has been isolated from the green bacteriumChloropseudomonas ethylica . It is enriched in bacteriochlorophylla and contains only a small amount of Chlorobium chlorophyll. Both a reaction-center bleaching (P840) and a cytochrome oxidation (C553) are observed to occur in the fraction. Particles that are contained in the fraction are larger than 1.5 × 106 daltons and exhibit a range of sizes consistent with some form of polymeric association of similar subunits. Around 80 bacteriochlorophylla molecules are present per P840. In an intact photosynthetic apparatus there are about 1000-1500 total chlorophylls (including Chlorobium chlorophyll) per reaction center.The redox potentials of the reaction center P840 and C553 were found to be 0.24 and 0.17 V, respectively, in one-electron reactions. The potentials of these components are around 0.2 V lower than comparable components found in other photosynthetic organisms.