... the GDP-mannose-4,6-dehydratase (GMD)into GDP-4-keto-6-deoxy-D-mannose, and t hen redu ced toGDP-D-rhamnose by GDP-4-keto-6-deoxy-D-mannosereductase (RMD). Here, we describe the enzymatic ... intoGDP-4-keto-6-deoxy-D-mannose by GDP-mannose-4,6-dehydratase (GMD) (Fig . 1). This 4-keto-6-deoxy interme-diate can be reduced to the GDP-monodeoxyhexose,GDP-L-fucose, GDP-D-rhamnose, GDP-deoxy-D-taloseor ... pentasaccharide units of manydifferent monosaccharides [3].Rhamnose is a deoxyhexose sugar found widely inbacteria and plants, but not in mammals. Of the twoisomers,LandD, the former is...