guanosine 50-diphosphate (GDP)-mannose pyrophosphorylasefrom Pyrococcus furiosus; N-acetylhexosamine 1-kinase from Bifidobacterium infantis; magnesium chloride; Escherichia coli inorganic pyrophosphatase in aq. buffer T=37°C; pH=8; 24 h; Enzymatic reaction;