The protein, Rsp3690, from Rhodobacter sphaeroides is a member of the amidohydrolase superfamily and is in the same group (cog1735) of proteins as bacterial phosphotriesterase. This enzyme was found to have relatively promiscuous activity for the hydrolysis of esters- both carboxylate and organophosphonate esters.Most importantly, Rsp3690 is able to hydrolyze the (SP)-enantiomer of isobutyl 4-nitrophenyl methylphosphonate 10 times faster than the less toxic (RP)-enantiomer. The high inherent catalytic activity of Rsp3690 for the hydrolysis of the toxic enantiomer of methylphosphonate esters make this enzyme an attractive target for directed evolution investigations.
