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SPECTRA AND EXTINCTION COEFFICIENTS OF NEAR‐INFRARED ABSORPTION BANDS IN MEMBRANES OF Rhodobacter sphaeroides MUTANTS LACKING LIGHT‐HARVESTING AND REACTION CENTER COMPLEXES
Author(s) -
Sturgis James N.,
Hunter C. Neil,
Niederman Robert A.
Publication year - 1988
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.1751-1097.1988.tb02817.x
Subject(s) - rhodobacter sphaeroides , bacteriochlorophyll , photosynthetic reaction centre , molar absorptivity , absorption (acoustics) , chemistry , rhodospirillaceae , rhodospirillales , rhodopseudomonas , membrane , extinction (optical mineralogy) , mutant , absorption spectroscopy , light harvesting complex , analytical chemistry (journal) , photochemistry , photosynthesis , chromatography , photosystem ii , optics , biochemistry , physics , mineralogy , electron transfer , gene
— Membranes from Rhodobacter (formerly Rhodopseudomonas) sphaeroides mutant strains that lack one or more of the bacteriochlorophyll a (BChl)‐protein complexes were used to obtain spectra and molar extinction coefficients of the near‐IR absorption bands. The strains examined were NF57 which lacks the B875 light‐harvesting and reaction center complexes, and M21 which lacks the B800–850light‐harvesting complex. The extinction coefficients obtained for the B800, B850 and B875 bands were 226 ± 10, 170 ± 5, and 118 ± 5 m M ‐1 cm ‐1 , respectively, in reasonable agreement with values reported for detergent‐isolated complexes (Clayton, R. K. and B. J. Clayton, Proc. Natl. Acad. Sci. USA 78 ,5583–5587, 1981). The results also demonstrated that detergent solubilization altered the spectra, causing a band broadening on the blue side of the B875 and B800 peaks. The data obtained from the analysis of the mutant strains were used for deconvolution of the BChl species in membranes of the wild‐type. A short BASIC computer program for performing this deconvolution is included.