Bacteriochlorophyll-protein complexes from the light-harvesting antenna of photosynthetic bacteria

Journal Article · Tue May 16 00:00:00 EDT 1978 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00603a033· OSTI ID:6818287

Sauer, K; Austin, L A

Detergent-solubilized bacteriochlorophyll--protein complexes corresponding to the light-harvesting antenna are isolated from Rhodopseudomonas sphaeroides, strain 2.4.1 (wild-type) and R-2 (carotenoidless) mutant, and from Rhodospirillum rubrum, wild-type. Detailed studies of the complex derived from the R-26 mutant indicate that it contains two bacteriochlorophyll (BChl) molecules and two copies of a peptide of 8.5 kdaltons, together with about 20 percent phospholipid in a unit of about 22 kdaltons. Distinctive absorption and circular dichroism spectra indicate that this unit is present in whole cell chromatophores derived from the bacteria, in large aggregates obtained by fractionation using Triton X-100 and as a monomeric unit in the presence of 0.5 percent sodium dodecyl sulfate. A similar component derived from the wild-type Rps. sphaeroides contains three BChl, two peptides of about 10 kdaltons, carotenoid, and phospholipid. The additional BChl molecule appears to be associated with an absorption band at 800 nm that is present in addition to the 850-nm band seen in the R-26 mutant complex. A similar complex from Rds. rubrum was studied in less detail. The interactions of the BChl molecules within these complexes are interpreted in terms of intermediate exciton coupling. Additional weaker reactions between the complexes in aggregates or in the intracytoplasmic membranes of the bacteria are invoked to account for fluorescence depolarization and fluorescence yield observations. Excitation transfer within the light-harvesting antenna that leads to photochemical trapping in the reaction centers is probably a direct consequence of these interactions.

• Research Organization: Univ. of California, Berkeley, CA (United States)
• OSTI ID: 6818287
• Journal Information: Biochemistry; (United States), Vol. 17:10
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CELL MEMBRANES
RECEPTORS
CHLOROPHYLL
COMPLEXES
PROTEINS
MOLECULAR STRUCTURE
RHODOPSEUDOMONAS
PHOTOSYNTHESIS
VISIBLE RADIATION
BACTERIA
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
ELECTROMAGNETIC RADIATION
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
MEMBRANES
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
RADIATIONS
SYNTHESIS
550200* - Biochemistry
550700 - Microbiology