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Characterization of a D1‐D2‐cyt b ‐559 complex containing 4 chlorophyll a /2 pheophytin a isolated with the use of MgSO 4
Author(s) -
Yruela I.,
van Kan P.J.M.,
Müller M.G.,
Holzwarth A.R.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)80377-3
Subject(s) - pheophytin , chemistry , p680 , chlorophyll , spinach , chlorophyll a , nuclear chemistry , photosystem ii , organic chemistry , photosynthesis , biochemistry , photosystem i
A D1‐D2‐cyt b ‐559 complex containing 4 chlorophyll a , 1 β‐carotene and 1 cytochrome b ‐559 per 2 pheophytin a has been isolated from spinach with 30% yield using a Q‐Sepharose Fast‐Flow anion‐exchange column equilibrated with 0.1% Triton X‐100, 10 mM MgSO 4 and 50 mM Tris‐HCl (pH 7.2). The preparation was then stabilized with 0.1% dodecyl‐β‐ d ‐maltoside. This method gave a yield 10 times higher than that using a Fractogel TSK‐DEAE 650(S) column equilibrated with 0.1% Triton X‐100, 30 mM NaCl and 50 mM Tris‐HCl (pH 7.2). The PS II RC complex was characterized using absorption and fluorescence spectroscopy at 277 and 77 K. A selective reversible bleaching under reducing conditions with maximum at 682 nm, associated with pheophytin a reduction, and light‐induced absorption differences with a lifetime of 1.0 ms, ascribed to the triplet state of P680 were measured and indicated that the isolated Dl‐D2‐cyt b ‐559 complex is active in charge separation. The results are compared with the data obtained for a PS II RC preparation containing 6 chlorophyll a , 2 β‐carotene and 1 cyt b ‐559 per 2 pheophytin a .