LCX carbamylated Lys, mutant H254G, H257W, I303T
Chemical and kinetic evidence for an essential histidine in the phosphotriesterase from Pseudomonas diminuta.
Structural characterization of the divalent cation sites of bacterial phosphotriesterase by 113Cd NMR spectroscopy.
Characterization of the zinc binding site of bacterial phosphotriesterase.
Three-dimensional structure of phosphotriesterase: an enzyme capable of detoxifying organophosphate nerve agents.
Identification of the histidine ligands to the binuclear metal center of phosphotriesterase by site-directed mutagenesis.
Utilization of copper as a paramagnetic probe for the binuclear metal center of phosphotriesterase.
Histidine-254 is essential for the inactivation of phosphotriesterase with the alkynyl phosphate esters and diethyl pyrocarbonate.
Three-dimensional structure of the binuclear metal center of phosphotriesterase.
Metal-substrate interactions facilitate the catalytic activity of the bacterial phosphotriesterase.
Three-dimensional structure of the zinc-containing phosphotriesterase with the bound substrate analog diethyl 4-methylbenzylphosphonate.
Mechanism-based inhibitors for the inactivation of the bacterial phosphotriesterase.
Perturbations to the active site of phosphotriesterase.
Augmented hydrolysis of diisopropyl fluorophosphate in engineered mutants of phosphotriesterase.
A combinatorial library for the binuclear metal center of bacterial phosphotriesterase.
Biochemical characterization and crystallographic structure of an Escherichia coli protein from the phosphotriesterase gene family.
Hydrolysis of phosphodiesters through transformation of the bacterial phosphotriesterase.
Phosphotriesterase: an enzyme in search of its natural substrate.
Mutagenesis of organophosphorus hydrolase to enhance hydrolysis of the nerve agent VX.
The binding of substrate analogs to phosphotriesterase.
High resolution X-ray structures of different metal-substituted forms of phosphotriesterase from Pseudomonas diminuta.
Structural determinants of the substrate and stereochemical specificity of phosphotriesterase.
Enhancement, relaxation, and reversal of the stereoselectivity for phosphotriesterase by rational evolution of active site residues.
Mobility of the active site bound paraoxon and sarin in zinc-phosphotriesterase by molecular dynamics simulation and quantum chemical calculation.
Ab initio structure of the active site of phosphotriesterase.
Successful molecular dynamics simulation of two zinc complexes bridged by a hydroxide in phosphotriesterase using the cationic dummy atom method.
Enzymatic synthesis of chiral organophosphothioates from prochiral precursors.
Enhanced degradation of chemical warfare agents through molecular engineering of the phosphotriesterase active site.
Coordination number of zinc ions in the phosphotriesterase active site by molecular dynamics and quantum mechanics.
Contribution of the active-site metal cation to the catalytic activity and to the conformational stability of phosphotriesterase: temperature- and pH-dependence.
This enzyme is activated in vitro by the addition of carbon dioxide, which carbamates the sidechain of Lys169, according to the literature [12]. This modified lysine residue is essential to bridge the two metal cofactors. Although early work (literature [1] & [4]) suggested that a general base to activate a water molecule, the water can be activated by the metal cofactor without any general base, according to the more recent literature ([8], [9], [10], [14]). In any case, the metal cofactors play the following roles (see [9]): (a) They can decrease pKa of th bound wate, increasing its nucleophilicity. (b) They can polarize the P=O bond (or P=S bond), and thereby facilitate the approach of the attacking hydroxyl ion, by increasing the electrophilic character of the phosphoryl core. (c) They can neutralize the development of the negative charge on the leaving group. The most recent literature [20] and structural information suggested that the catalytic reaction of this enzyme proceeds via SN2-like mechanism as follows: (1) Phosphoryl-oxygen bond is polarized by its interaction with zinc-2. (2) A water or hydroxide ion bridging the two zinc ions is activated by the two zinc ions (particulary zinc-1) and Asp301 (as a general base). (3) The activated water makes a nucleophilic attack on the phosphorus atom, releasing the leaving phenol group.