Mössbauer studies of the non-heme iron and cytochrome b559 in a Chlamydomonas reinhardtii PSI− mutant and their interactions with α-tocopherol quinone

AbstractSpin and valence states of the non-heme iron and the heme iron of cytochrome b559, as well as their interactions with α-tocopherol quinone (α-TQ) in photosystem II (PSII) thylakoid membranes prepared from the Chlamydomonas reinhardtii PSI− mutant have been studied using Mössbauer spectroscopy. Both of the iron atoms are in low spin ferrous states. The Debye temperature of the non-heme is 194 K and of the heme iron is 182 K. The treatment of α-TQ does not change the spin and the valence states of the non-heme iron but enhances the covalence of its bonds. α-TQ oxidizes the heme iron into the high spin Fe3+ state. A possible role of the non-heme iron and α-TQ in electron flow through the PSII is discussed