Iron components in PS II particles of spinach by Mössbauer spectroscopy

Mössbauer spectrum measured for the iron components of photosystem II (PS II) particles of spinach is a superposition of 4 doublets. Quadrupole splitting and chemical shifting of doublets I–IV are characteristics of proteins with oxidized cytochrome b-559, reduced cytochrome b-559, Fe3+-Q complex and Fe2+ -Q complex respectively. After the PS II particles are treated with La3+, two doublets of Fe2+ disappear and Fe2+ is converted into Fe3+, indicating that the reduced cytochrome b-559 has been converted into the oxidized cytochrome b-559, and Fe2+ -Q complex into Fe3+ -Q complex. The Mössbauer spectrum of PS II particles treated with La3+ and Ca2+ shows that Ca2+ can weaken the inhibitory effect of La3+ in part, and a portion of the reduced cytochrome b-559 and Fe-Q complex still exist.