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TRANS ‐MEMBRANE LOCALIZATION OF REACTION CENTER PROTEINS IN RHODOPSEUDOMONAS SPHAEROIDES CHROMATOPHORES
Author(s) -
Hall Robert L.,
Doorley Peter F.,
Niederman Robert A.
Publication year - 1978
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1978.tb07708.x
Subject(s) - chromatophore , pronase , photosynthetic reaction centre , protein subunit , chemistry , trypsin , rhodospirillales , rhodospirillum rubrum , biochemistry , biophysics , biology , photosynthesis , enzyme , fishery , gene
— Rhodopseudomonas sphaeroides NCIB 8253 chromatophores were treated with trypsin and pronase to determine which of the three reaction center subunits was exposed at the outer surface and susceptible to digestion. Trypsin (37°C, 60min) produced no detectable digestion of any subunit, based on SDS polyacrylamide gel electrophoresis analysis. Pronase (37°C, 60min) digested the H (28 kdalton) subunit but left the M (22 kdalton) and L (19 kdalton) subunits intact. We conclude that the H subunit is significantly exposed at the outer chromatophore surface but that the M and L subunits are probably not externally exposed. Chromatophores which had been pronase‐treated were fully photochemically active, as measured by light‐induced carotenoid bandshift at 522 nm. The H subunit is apparently unnecessary for primary photochemistry in situ.