Myxoxanthophyll Myxoxanthophyll Myxoxanthophyll is a carotenoid glycoside pigment present (usually as rhamnosides) in the photosynthetic apparatus of cyanobacteria. It is named after the word ""Myxophyceae"", a former term for cyanobacteria. As a monocyclic xanthophyll, it has a yellowish color. It is required for normal cell wall structure and thylakoid organization in the cyanobacterium "Synechocystis". The pigment is unusual because it is glycosylated on the 2'-OH rather than the 1'-OH position of the molecule. Myxoxanthophyll was first isolated from "Oscillatoria rubenscens" in 1936. The bright red pigment lycopene is the acyclic precursor of all carotenoids in cyanobacteria. In myxoxanthophyll synthesis, lycopene is
Photosynthetic pigment other groups of bacteria use the bacteriochlorophyll pigments (similar to the chlorophylls) for photosynthesis. Unlike the cyanobacteria, these bacteria do not produce oxygen; they typically use hydrogen sulfide rather than water as the electron donor. Recently, a very different pigment has been found in some marine γ-proteobacteria: proteorhodopsin. It is similar to and probably originated from bacteriorhodopsin (see below: under Archaea). Bacterial chlorophyll b has been isolated from Rhodopseudomonas spp. but its structure is not yet known to us. Halobacteria use the pigment bacteriorhodopsin which acts directly as a proton pump when exposed to light. Photosynthetic pigment A photosynthetic pigment