title: Energy transfer between the carotenoid and the bacteriochlorophyll within the B-800-850 light-harvesting pigment-protein complex of Rhodopseudomonas sphaeroides.
abstract: Energy transfer between carotenoid and bacteriochlorophyll has been studied in isolated B-800-850 antenna pigment-protein complexes from different strains of Rhodopseudomonas sphaeroides which contain different types of carotenoid. Singlet-singlet energy transfer from the carotenoid to the bacteriochlorophyll is efficient (75-100%) and is rather insensitive to carotenoid type, over the range of carotenoids tested. The yield of carotenoid triplets is low (2-15%) but this arises from a low yield of bacteriochlorophyll triplet formation rather than from an inefficient triplet-triplet exchange reaction. The rate of the triplet-triplet exchange reaction between the bacteriochlorophyll and the carotenoid is fast (Ktt greater than or equal to 1.4 . 10(8) S-1) and also relatively independent of the type of carotenoid present.
mesh_terms: D001429:Bacteriochlorophylls / Q000378:metabolism*; D002338:Carotenoids / Q000378:metabolism*; D002734:Chlorophyll / Q000031:analogs & derivatives*; D004735:Energy Transfer; D007700:Kinetics; D009154:Mutation; D010782:Photolysis; D012242:Rhodobacter sphaeroides / Q000378:metabolism*; D013045:Species Specificity; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry
chemical_list: D001429:Bacteriochlorophylls; D002734:Chlorophyll; D002338:Carotenoids