GDP-activated sugars

Investigation of the human FX protein has recently revealed its remarkable involvement in the in vivo synthesis of GDP-Fuc from GDP-Man. The purified enzyme had combined epimeiase and NADPH-reductase activity, converting GDP-4-keto-6-deoxymannose into GDP-Fuc [88]. The very same reaction sequence is also achieved by use of a crude extract from A. aerogenes, and has been used to prepare C-labeled GDP-Fuc [89]. 

The protein extract probably contained both a fucokinase to generate fucose-1-phosphate and GDP-fucose pyrophosphorylase. This same analytical protocol was later on applied by chemists to synthesize small amounts of GDP-Fuc [92]. 

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