Purification and properties of the phosphotriesterase from Pseudomonas diminuta.
Structural and catalytic diversity within the amidohydrolase superfamily.
The amidohydrolase superfamily comprises a remarkable set of enzymes that catalyze the hydrolysis of a wide range of substrates bearing amide or ester functional groups at carbon and phosphorus…
Structure of carbamoyl phosphate synthetase: a journey of 96 A from substrate to product.
The two halves of the large subunit are related by a nearly exact 2-fold rotational axis, thus suggesting that this polypeptide chain evolved from a homodimeric precursor.
Molecular structure of dihydroorotase: a paradigm for catalysis through the use of a binuclear metal center.
From the three-dimensional structures of the enzyme-bound substrate and product, it has been possible to propose a unique catalytic mechanism for dihydroorotase, and strikingly, in subunit II, carbamoyl L-aspartate is observed binding near the binuclear metal center with its carboxylate side chain ligating the two metals and thus displacing the bridging hydroxide ion.
Mechanism for the hydrolysis of organophosphates by the bacterial phosphotriesterase.
A mechanism for the hydrolysis of organophosphates by the bacterial PTE has been proposed and is consistent with the existence of a proton relay from Asp301 to His254 to Asp233 that is used to ferry protons away from the active site with substrates that do not require activation of the leaving group phenol.
Characterization of the zinc binding site of bacterial phosphotriesterase.
High resolution X-ray structures of different metal-substituted forms of phosphotriesterase from Pseudomonas diminuta.
By measuring the anomalous X-ray data from crystals of the Zn(2+)/Cd(2-)-species, it has been possible to determine that the alpha-metal ion is zinc and the beta-site is occupied by cadmium.
Catalytic mechanisms for phosphotriesterases.
Channeling of substrates and intermediates in enzyme-catalyzed reactions.
The three-dimensional structures of tryptophan synthase, carbamoyl phosphate synthetase, glutamine phosphoribosylpyrophosphate amidotransferase, and asparagine synthetase have revealed the relative…
Three-dimensional structure of the zinc-containing phosphotriesterase with the bound substrate analog diethyl 4-methylbenzylphosphonate.
The position of the inhibitor within the active site suggests that the nucleophile for the hydrolysis reaction is the metal-bound hydroxide, and this most likely explains the broad substrate specificity exhibited by phosphotriesterase.