Linear and circular dichroism of membranes from Rhodopseudomonas capsulata.
Absorption, linear dichroism and circular dichroism spectra of Rhodopseudomonas capsulata (wild-type-St. Louis strain, mutant Y5 and mutant Ala+) are particularly sensitive to the nature of the light-harvesting bacteriochlorophyll-carotenoid-protein complexes. Evidence for exciton-type interactions is seen near 855 nm in the membranes from the wild-type and from mutant Y5, as well as in an isolated B-800 + 850 light-harvesting complex from mutant Y5. The strong circular dichroism that reflects these interactions is attenuated more than 10-fold in membranes from the Ala+ mutant, which lacks both B-800 + 850 and colored carotenoids and contains only the B-875 light-harvesting complex. These results lead to the conclusion that these two light-harvesting complexes have significantly different chromophore arrangements or local environments.
D002462:Cell Membrane / Q000378:metabolism*; D002942:Circular Dichroism; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D009154:Mutation; D011487:Protein Conformation; D012241:Rhodopseudomonas / Q000378:metabolism*; D013053:Spectrophotometry
D008565:Membrane Proteins