Mössbauer Spectroscopy on Photosynthetic Bacteria: Investigation of Reaction Centers of Rhodopseudomonas Viridis

Abstract

Crystals of 57Fe enriched reaction centers have been investigated by Mossbauer spectroscopy. The cytochrome irons are in the low spin ferric state. The non-heme iron of the electron accepting side is partly ferrous high spin and partly ferrous low spin (or ferric high spin). Under the conditions of the experiment sodium ascorbate reduces only one cytochrome iron into the ferrous low spin state. Membrane bound proteins become flexible at higher temperatures than proteins with a hydrophilic surface. They are also less flexible, at least up to temperatures of about 250 K.