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
Lycopene Lycopene is a key intermediate in the biosynthesis of carotenoids, such as beta-carotene, and xanthophylls. The unconditioned biosynthesis of lycopene in eukaryotic plants and in prokaryotic cyanobacteria is similar, as are the enzymes involved. Synthesis begins with mevalonic acid, which is converted into dimethylallyl pyrophosphate. This is then condensed with three molecules of isopentenyl pyrophosphate (an isomer of dimethylallyl pyrophosphate), to give the 20-carbon geranylgeranyl pyrophosphate. Two molecules of this product are then condensed in a tail-to-tail configuration to give the 40-carbon phytoene, the first committed step in carotenoid biosynthesis. Through several desaturation steps, phytoene is converted into lycopene. The