Photosystem II complex from Cyanidioschyzon merolae

Abstract

Photosystem II (PS II) complex was highly purified from a thermo- and acidophilic primitive red alga, Cyanidioschyzon merolae by solubilizing thylakoid membrane with n-dodecyl-β-D-maltoside followed by anion-exchange chromatography. About 80% of PS II complex was in a dimeric form of ~620 kDa that evolved oxygen at a rate of 3,300 μmol O₂/mg Chl/h. The rest of PS II complex was in a monomeric form of ~ 440 kDa that evolved oxygen at a rate of 2,900 μmol O₂/mg Chl/h. Electron microscopy observation showed that the sizes of dimeric and monomeric forms were 25 nm x 40 nm and 25 nm x 15 nm, respectively. Polypeptide analysis of these PS II complexes revealed that Psb27 was associated with only monomeric form of PS II complex.