Structure of enzyme-bound nucleotides

Enzyme P specificity8 Pp specificity a Metal- ATP -nucleotide specificity ADP Ref. 

Two specific examples from Table 2 are worthy of further mention. Nucleoside phosphotransferase, which catalyzes Equation 20, had been proposed not to involve a double-displacement mechanism or an intermediate phosphoryl-enzyme. 

This proposal was based on kinetic data and failure to detect an intermediate. The stereochemical test showed the reaction to proceed with retention of configuration and led to the proposal that such an intermediate is involved [27], The phosphoryl-enzyme was subsequently isolated in good yield. This was the first study in which stereochemistry cast doubt on an earlier mechanistic proposal and provided the first evidence of a double-displacement pathway, later verified by the isolation of the intermediate. 

coli acetate kinase has been the subject of controversy regarding whether a double- or single-displacement pathway is followed. On the one hand a phosphoryl- 

Two pairs of chemically matched reactions exemplify the importance of shared binding sites in the evolution of double-displacement pathways. They are the reactions catalyzed by UDP-glucose pyrophosphorylase (inversion) [74] and galactose- -P uridylyltransferase (retention) [21], which catalyze Reactions 21 and 22, 

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