The Identification of 3-O-Methyl-l-Rhamnose (l-Acofriose) as Constituent of the Lipopolysaccharide of Rhodopseudomonas capsulata

From the lipopolysaccharide of the gram-negative bacterium Rhodopseudomonas capsulata (Athiorhodaceae) a lipophilic sugar was isolated by chromatographic procedures and characterized by mass spectrometry as belonging to the group of 3-O-methyl-6-deoxy-hexoses. Demethylation showed that the parental sugar had the same properties in borate electrophoresis as rhamnose. Comparison with an authentic sample of 3-O-methyl-rhamnose in gas liquid chromatography, paper chromatography and borate electrophoresis showed that the sugar under examination is 3-O-methylrhamnose (acofriose). Investigation of its optical rotation indicates that the sugar has the l-configuration. l-Acofriose (3-O-methyl-l-rhamnose) has not hitherto been found in lipopolysaccharides of gram-negative bacteria.