Cytochromes of a Blue-Green Alga: Extraction of a c-Type with a Strongly Negative Redox Potential

Abstract
Aqueous extraction of lyophilized Anacystis nidulans cells followed by chromatography on diethylaminoethyl cellulose separates three different c-type cytochromes. Of the two present in highest concentration, cytochrome-554 has a + 0.35-volt redox potential and resembles the cytochrome f of other photosynthetic tissues, while cytochrome-549 has a -0.26-volt potential. The possible participatidn of cytochrome-549 in electron transport in photosynthesis in this alga at a more negative oxidation-reduction potential than previously postulated for any cytochrome is inferred from the similarities in its spectra to the light-induced spectral changes in vivo observed by others.