lipopolysaccharide biosynthesis LPS oligosaccharide biosynthesis PMID:11371519 UPa:UPA00301 Biosynthesis of inner core oligosaccharide, a component of lipopolysaccharide (LPS) molecules. Core oligosaccharide contains unusual sugars (e.g. KDO, keto-deoxyoctulonate and heptulose). It contains two glucosamine sugar derivatives each containing three fatty acids with phosphate or pyrophosphate attached. The core polysaccharide is attached to lipid A, which is also in part responsible for the toxicity of gram-negative bacteria. pathway LPS inner core oligosaccharide biosynthesis glycan biosynthesis