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CIRCULAR DICHROISM OF LIGHT‐HARVESTING COMPLEXES FROM PURPLE PHOTOSYNTHETIC BACTERIA *
Author(s) -
Cogdell Richard J.,
Scheer Hugo
Publication year - 1985
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.1751-1097.1985.tb01629.x
Subject(s) - bacteriochlorophyll , light harvesting complex , circular dichroism , chemistry , exciton , photosynthesis , purple bacteria , antenna (radio) , chlorosome , spectral line , carotenoid , wavelength , photochemistry , protein secondary structure , crystallography , photosystem ii , materials science , photosynthetic reaction centre , physics , biochemistry , optoelectronics , telecommunications , quantum mechanics , astronomy , computer science
— The CD spectra of a range of antenna complexes from several different species of purple photosynthetic bacteria were recorded in the wavelength range of 190 to 930 nm. Analysis of the far UV CD (190 to 250 nm) showed that in each case except for the B800‐850 from Chr. vinosum the secondary structure of the light‐harvesting complexes contains a large amount of α‐helix (˜50%) and very little 0‐pleated sheet. This confirms the predictions of the group of Zuber of a high a‐helical content based upon consideration of the primary structures of several antenna apoproteins. The CD spectra from the carotenoids and the bacteriochlorophylls show considerable variations depending upon the type of antenna complex. The different amplitude ratios in the CD spectrum for the bacteriochlorophyll Qy, Qx and Soret bands indicate not only different degrees of exciton coupling, but also a strong and variable hyperchromism (Scherz and Parson, 1984a, b).