Premium
CAROTENOID‐TO‐BACTERIOCHLOROPHYLL SINGLET ENERGY TRANSFER IN CAROTENOID‐INCORPORATED B850 LIGHT‐HARVESTING COMPLEXES OF Rhodobacter sphaeroides R‐26.1
Author(s) -
Frank Harry A.,
Farhoosh Roya,
Aldema Mila L.,
DeCoster Beverly,
Christensen Ronald L.,
Gebhard Ronald,
Lugtenburg Johan
Publication year - 1993
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.1751-1097.1993.tb02254.x
Subject(s) - bacteriochlorophyll , rhodobacter sphaeroides , photochemistry , chemistry , photosynthetic reaction centre , excited state , singlet state , purple bacteria , carotenoid , rhodobacter , fluorescence , electron transfer , light harvesting complex , photosynthesis , atomic physics , photosystem ii , physics , optics , biochemistry , food science , mutant , gene
Four carotenoids, 3,4,7,8‐tetrahydrospheroidene, 3,4,5,6‐tetrahydrospheroidene, 3,4‐dihydrospheroidene and spheroidene, have been incorporated into the B850 light‐harvesting complex of the carotenoidless mutant, photosynthetic bacterium, Rhodobacter sphaeroides R‐26.1. The extent of π‐electron conjugation in these molecules increases from 7 to 10 carbon‐carbon double bonds. Carotenoid‐to‐bacteriochlorophyll singlet state energy transfer efficiencies were measured using steady‐state fluorescence excitation spectroscopy to be 54 ± 2%, 66 ± 4%, 71 ± 6% and 56 ± 3% for the carotenoid series. These results are discussed with respect to the position of the energy levels and the magnitude of spectral overlap between the S, (2′AJ state emission from the isolated carotenoids and the bacteriochlorophyll absorption of the native complex. These studies provide a systematic approach to exploring the effect of excited state energies, spectral overlap and excited state lifetimes on the efficiencies of carotenoid‐to‐bacteriochlorophyll singlet energy transfer in photosynthetic systems.