COMPARISON OF PHOTOTRAP COMPLEXES FROM CHROMATOPHORES OF RHODOSPIRILLUM RUBRUM, RHODOPSEUDOMONAS SPHEROIDES, AND THE R‐26 MUTANT OF RHODOPSEUDOMONAS SPHEROIDES*

R. L. HALL*, Mayfair Kung, M. Fu, B. J. Hales, Paul A Loach

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Abstract— After dissolution of the membrane structure of chromatophores from Rhodospirillum rubrum, Rhodopseudomonas spheroides, and the R‐26 mutant of Rhodopseudomonas spheroides, active phototrap complexes from each have been purified by a column electrophoresis procedure. Phospholipids and transition metals were well separated from the phototrap complex in all three systems. The purified R. rubrum phototrap complex retained a full complement of antenna bacteriochlorophyll and carotenoid pigments which had nearly the same absorbance spectra as in the intact cell, and which delivered absorbed light energy to the phototrap with just as high efficiency as in the intact cell. Sodium dodecyl sulfate (SDS) disc gel electrophoresis using Tris buffer showed that these preparations often contained only two prominent polypeptides of 30,000 ± 2000 and 12,000 ± 4000 mol. wt., and a lesser amount of a third polypeptide of 21,000 ± 2000 mol. wt. The phototrap complexes prepared from the wild type and the R‐26 mutant of R. spheroides were similar, in that a partial separation from antenna pigments occurred during column electrophoresis. Both complexes had prominent polypeptides of 24,000 ± 2000 and 21,000 ± 2000 mol. wt., but no polypeptide of 30,000 mol. wt remained after electrophoresis. A third major polypeptide occurred with a mol. wt. of about 12,000 but seemed identifiable with an incompletely separated antenna pigment fraction. The phototrap complex prepared from the R‐26 mutant had a typical reaction center spectrum. In the case of wild type R. spheroides purification, two distinct protein‐pigment complexes separated. Although the absorbance of the bacteriochlorophyll and carotenoid pigments were little changed from those of the in vivo system, different polypeptides in the two fractions were observed by SDS disc gel electrophoresis; only one fraction seemed to be intimately related with the phototrap complex.

Original languageEnglish (US)
Pages (from-to)505-520
Number of pages16
JournalPhotochemistry and Photobiology
Volume18
Issue number6
DOIs
StatePublished - Jan 1 1973

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry

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