Pyrophosphatase pyrophosphate sugars

The main component of the adenosine diphosphate sugar fraction from a Salmonella typhimurium strain was unexpectedly found to be adenosine 5 -(D-mannitol 1-pyrophosphate)190 (45). Upon treatment with acid or with snake-venom pyrophosphatase, it produces adenosine 5 -phosphate and D-mannitol 1-phosphate these observations confirm the structure assigned. 

The reaction is catalyzed by specific enzymes, usually termed204 sugar nucleotide pyrophosphorylases. The equilibrium constant is not far from unity, and addition of inorganic pyrophosphatase, an enzyme that converts inorganic pyrophosphate irreversibly into... 

Hydrolysis of sugar nucleotides with unspecific pyrophosphatases has already been mentioned (Section 11,1, p. 310). A similar reaction is catalyzed by a bacterial enzyme specific for adenosine 5 -(a-D-glucopyranosyl pyrophosphate).459 The specific conversion of uridine 5 -(a-D-glucopyranosyl pyrophosphate) into a-D-glucopyranosyl phosphate, uridine, and inorganic phosphate was observed with an enzyme from Escherichia colt 459,460 a preparation from Bacillus subtilis can act in a similar manner461 on different sugar nucleotides. ... 

The in vivo synthesis of GDP-mannose is equivalent to that of the UDP-sugars [29, 30] (see Scheme 12). Mannose-1-phosphate, prepared from maimose-6-phos-phate either by a phosphomutase reaction or chemically [61], is converted to GDP-mannose by a GDP-mannose pyrophosphorylase in the presence of GTP [86]. Also in this case a pyrophosphate side-product is generated which must be decomposed by a pyrophosphatase to shift the equilibrium to the desired GDP-Man. GDP-3-azido- and GDP-3-A-acetylmannose have also been obtained successfully by following this pathway [60]. 

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