Myxoxanthophyll in Synechocystis sp. PCC 6803 is Myxol 2′-Dimethyl-Fucoside, (3R,2′S)-Myxol 2′-(2,4-di-O-Methyl-α-l-Fucoside), not Rhamnoside

Open Access
Publisher Website
Google Scholar
Abstract
We identified the molecular structures of the carotenoids in Synechocystis sp. PCC 6803. Myxoxanthophyll in this cyanobacterium was myxol 2′-dimethyl-fucoside, (3R,2′S)-myxol 2′-(2,4-di-O-methyl-α-l-fucoside). The sugar moiety of the pigment was not rhamnose but dimethylated fucose, which has not been reported in carotenoid glycosides. The other carotenoids were β-carotene, (3R,3′R)-zeaxanthin, echinenone, (3′R)-3′-hydroxyechinenone and deoxymyxol 2′-dimethyl-fucoside, (2′S)-deoxymyxol 2′-(2,4-di-O-methyl-α-l-fucoside). Generally, the group of polar carotenoids in cyanobacteria is referred to as myxoxanthophyll, and the structure is considered to be myxol 2′-rhamnoside. Since the name myxoxanthophyll can not specify the sugar moiety and the identification of the sugar moiety is unfeasible in many cyanobacteria, we propose the following naming convention: when the sugar moiety is unknown, the name is myxol glycoside, when known, as in the case of rhamnose and α-l-fucose, they should be named myxol 2′-rhamnoside and myxol 2′-α-l-fucoside, respectively.
Keywords