Abstract
Cytochrome b-559 is an integral protein of photosystem II complexes (PSII). However, the number of cytochrome b-559 (cyt b-559) associated with the PSII reaction center has been subject of controversy. Some studies have concluded that there is one heme equivalent of cyt b-559 per reaction center, some have found two, and others have reported intermediate value.
In this study, PSII complex highly active in oxygen evolution was purified from a thermophilic cyanobacterium, Synechococcus vulcanus (S.v.) and used to determine the cyt b-559 contents. Our work shows that, depending on the method used to estimate pheophytin a and reduction minus oxidation difference absorptoin spectra of cyt b-559 and cyt c by deconvolution of the original spectra, the S.v. preparation contains 1.0 cyt b-559 and 1.0 cyt c per reaction center.
Moreover, we compare the cyt b-559 content in a cyanobacterial and a spinach PSII preparation.
