Low Molecular Weight Polypeptides in Photosystem II and Protein Dependent Acceptor Requirement for Photosystem II

Abstract

Recently, several preparations of Photosystem II (PS II) core particles, with oxygen evolving capacity, have been reported (1–4). They all show a quite similar and simple polypeptide pattern. These PS II core preparations are of great interest for the elucidation of what polypeptides are required for the catalytic PS II functions. It is, therefore, important that all polypeptides in these preparations are identified and characterized. Recently, we found, by improved gel electrophoresis, that the PS II core particles isolated according to Ikeuchi et al. (2) contained a number of low molecular weight polypeptides (5) that were not reported in the original work. This study has now been extended to include comparison with two additional PS II core preparations, those described by Ghanotakis et al. (3) and Franrén (4). Our results suggest that three out of eight identified low molecular weight polypeptides (4, 5 and 5.5 kDa) are obligatory for catalytic PS II function.