Open AccessInvestigation of the structure of spinach photosystem II reaction center complex
Author(s) -
Tsiotis Georgios,
Psylinakis Manolis,
Woplensinger Bettina,
Lustig Ariel,
Engel Andreas,
Ghanotakis Demetrios
Publication year - 1999
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1999.00042.x
Subject(s) - spinach , photosynthetic reaction centre , photosystem ii , center (category theory) , chemistry , photosynthesis , crystallography , biochemistry
The photosystem II (PSII) reaction center (RC) complex was isolated from spinach and characterized by gel electrophoresis, gel filtration and analytical ultracentrifugation. The purified complex contained the PsbA, PsbD, PsbE, PsbF and PsbI subunits. Gel filtration and analytical ultracentrifugation indicated the presence of a homogeneous complex. The mass of the RC complexes was found to be 107 kDa by analytical ultracentrifugation and 132 kDa by scanning transmission electron microscopy (STEM). The mass obtained showed the isolated complex to exist as a monomer and only one cytochrome b 559 (cyt b 559 ) to be associated with the RC complex. Digital images of negatively stained RC complexes were recorded by STEM and analyzed by single‐particle averaging. The complex was 9 nm long and 5 nm wide, and exhibited a pronounced quasi‐twofold symmetry. This supports the symmetric organization of the PSII complex, with the PsbA and the PsbD proteins in the center and symmetrically arranged PsbB and PsbC proteins at the periphery of the monomeric complex.