Protein identification of purified particles isolated from spinach thylakoids by deoxycholate electrophoresis

Three thylakoid complexes were isolated by deoxycholate preparative electrophoresis. The protein composition of each fraction was analyzed by SDS analytical electrophoresis. No protein of the PS 1 enriched fraction (fraction 1) was found in the PS 2 enriched fraction (fraction 2) and inversely. The antenna complex (fraction 3) did not have any contamination by proteins of fraction 1 or fraction 2. Fraction 1 was mainly composed of the CP1, the reaction center complex of the PS1, and by low molecular weight proteins, previously found in other PS 1 preparations. Tentative assignments of these proteins are presented; among them are iron sulfur proteins. After analytical SDS electrophoresis of fraction 2, the reaction center complex was dissociated. Nevertheless three proteins of 50 kD, 42 kD and 35 kD were assigned to this complex. Fraction 2 contained also the three cytochromes of the thylakoid membranes: cyt f, cyt b6, cyt b559. Fraction 3 was exclusively composed of one protein pigment complex, CP2.Abbreviations SDS sodium dodecyl sulfate - PS 1 photosystem 1 - PS 2 photosystem 2 - CP1, CP2 protein pigment complexes isolated by SDS electrophoresis - cyt cytochromes - P700 primary electron donor of PS 1 - P680 primary electron donor of PS 2 - DOC deoxycholate - Q primary plastoquinone electron acceptor - CF coupling factor