Two c-type cytochromes from light- and dark-grown Euglena.

A pigment-protein complex can be extracted, in aqueous 2-percent digitonin, from Euglena grown in the light. When further fractionated by acetone and ammonium sulfate this flagellate yields a c-type cytochrome. By similar extraction of dark-grown, nonphotosynthetic Euglena, another c-type cytochrome can be isolated. The cytochrome from the light-grown Euglena- is like that of cytochrome c isolated from a photosynthetic bacterium. The cytochrome from the dark-grown Euglena is like cytochrome f found in the chloroplasts of higher plants.