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Stoichiometry and turnover of photosystem II polypeptides
Author(s) -
Gounaris Kleoniki,
Pick Uri,
Barber James
Publication year - 1987
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(87)81281-4
Subject(s) - photosystem ii , biochemistry , spinach , biology , monomer , fractionation , photosystem , cyanobacteria , molecular mass , chemistry , photosynthesis , chromatography , enzyme , bacteria , genetics , organic chemistry , polymer
Using Triton X‐100 solubilization and sucrose gradient fractionation, a photosystem II core complex has been isolated from the green alga Dunaliella salina . The complex was similar to that previously isolated from spinach [(1985) FEBS Lett. 188, 68‐72] being composed of five main polypeptides of apparent molecular masses, 47, 40, 32, 30 and 10 kDa. Studies using 14 C indicate that with either dark or illuminated cells the Stoichiometry of these polypeptides is 1:1:1:1:1 with about 20 chlorophyll a molecules per monomeric unit. According to 35 S labelling only the 32 kDa polypeptide, identified as the D1 or Q B binding protein by immunoblotting, is rapidly turning over at a rate greater than the growth rate. The level of labelled sulphur associated with each polypeptide is reasonably consistent with the amino acid content derived from gene sequences and identifies the 47, 40, 32, 30 and 10 kDa apoproteins as products of the psbB , psbC , psbA , psbD and psbE genes.