Methanol esterification reactions catalyzed by snake venom and bovine intestinal 5′‐nucleotide phosphodiesterases

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Abstract
It is not known whether the enzymes 5′‐nucleotide phosphodiesterase/nucleotide pyrophosphatase (EC 3.1.4.1/EC 3.6.1.9) catalyze the transfer of nucleotides to acceptors other than water. We have investigated the action of snake venom and bovine intestinal mucosa phosphodiesterases on nucleoside 5′‐polyphosphates in the presence of methanol. In those conditions, GTP was converted by snake venom phosphodiesterase to a mixture of GMP and another compound with a different retention time in reverse‐phase high‐performance liquid chromatography. That compound, by ultraviolet, 1H‐ and 13C‐nuclear magnetic resonance spectroscopic analysis, and by enzyme analysis, was characterized as the methyl ester of GMP (GMP‐OMe). The molar fraction [GMP‐OMe]/ [GMP + GMP‐OMe] formed was higher than the molar fraction of methanol as a solvent in reaction mixtures. Similar reactions took place at comparable rates with snake venom and bovine intestinal mucosa phosphodiesterases using several nucleoside 5′‐polyphosphates as substrates. The ability of 5′‐nucleotide phosphodiesterases to catalyze transfer reactions to a non‐water acceptor is relevant to the mechanism of the enzymes, to their use as analytical tools, and to their possible use/role in the preparative/in vivo synthesis of nucleotide esters.