Binding of carotenoids on reaction centers from Rhodopseudomonas sphaeroides R 26

摘要: Abstract The carotenoid-less reaction centers isolated from Rhodopseudomonas sphaeroides (strain R 26) bind pure all-trans spheroidene as well spheroidenone in a nearly 1:1 molar ratio with respect to P-870. Neither β-carotene nor spirilloxanthin, both absent wild-type Rps. sphaeroides, could be bound appreciable amounts. Resonance Raman spectra of the carotenoidreaction center complex indicate that carotenoid is cis isomer, its conformation being very close, although probably not identical, assumed by centers. electronic absorption carotenoid-reaction complexes are good agreement such interpretation. When 26 centers, displays light-induced absorbance changes identical peak wavelengths and comparable amplitudes those observed Thus binding most likely occurs at same proteic site This shows selectivity towards nature carotenoids, has sterical requirement wild type, leading isomerisation.