Enzymic hydrolysis of phosphonate esters. Reaction mechanism of intestinal 5'-nucleotide phosphodiesterase.

The mechanism of bovine intestinal 5'-nucleotide phosphodiesterase was investigated by determining kinetic constants of systematically varied substrates, with emphasis on esters of phosphonic acids (which have much higer Vmax values than conventional phosphodiester substrates), and by pre-steady-state kinetics using bis(4-nitrophenyl) phosphate as substrate. The results suggest a ping-pong type mechanism, with participation of a covalent enzyme intermediate.