Mn-preserving extraction of 33-, 24- and 16-kDa proteins from O2-evolving PS II particles by divalent salt-washing

AbstractDivalent salt-washing of O2-evolving PS II particles caused total liberation of 33-, 24- and 16-kDa proteins, but the resulting PS II particles retained almost all amounts of Mn present in initial particles. The retained Mn was EPR-silent when the particles were kept in high concentrations of divalent salt. By divalent salt-washing, the activity of diphenylcarbazide (DPC) photooxidation was not affected at all, neither suppressed nor enhanced, while O2 evolution was totally inactivated. These results indicate that Mn can be kept associated with PS II particles even after liberation of the 33-kDa protein, and suggest that the 33-kDa protein is probably not responsible for binding Mn onto membranes, but is possibly responsible for maintaining the function of Mn atoms in the O2-evolving center