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SPECTROSCOPIC CHARACTERIZATION OF TWO FORMS OF THE D1‐D2‐CYTOCHROME b559 COMPLEX FROM SUGAR BEET
Author(s) -
Montoya Guillermo,
Cases Rafael,
Yruela Inmaculada,
Picorel Rafael
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.tb04959.x
Subject(s) - pheophytin , chemistry , chlorophyll , photochemistry , analytical chemistry (journal) , absorption (acoustics) , p680 , absorption spectroscopy , raman spectroscopy , resonance raman spectroscopy , photosynthesis , photosystem ii , chromatography , optics , biochemistry , organic chemistry , photosystem i , physics
Two D1‐D2‐cytochrome b559 complex forms, called RCIIa and RCIIb, with different pigment stoichi‐ometry were characterized using absorption and surface‐enhanced resonance Raman scattering spectroscopy and spectral gaussian deconvolution. Electronic absorption spectra of the RCIIb at 277 K showed significant differences compared to RCIIa, i.e . a strong decrease in the absorbance due to carotenoid and chlorophyll for the same amount of pheophytin. A reduced carotenoid and chlorophyll content in RCIIb was also observed in the surface‐enhanced resonance Raman scattering spectra. Spectral deconvolution elicited three main absorption bands at 680, 672 and 669–670 nm, which were ascribed to P680, pheophytin and accessory chlorophyll, respectively. In addition, a minor component around 667 nm was observed in the RCIIb, most probably due to some reaction center inactivation. Calculation of the relative area under the gaussians together with pigment stoichiometry data suggest that the 680, 672 and 669–670 nm components contain, respectively, two chlorophylls, two pheophytins and four chlorophylls for the RCIIa, and two chlorophylls, two pheophytins and two chlorophylls for the RCIIb.