Two Enzymes for the Detoxicatlon of Organophosphorus Compounds—Sources, Similarities, and Significance

Hoskin, F. C. G.; KIRKISH, MARY ANN; Steinmann, Kathleen E.

doi:10.1093/toxsci/4.2part2.165

Cited by 11 publications

(20 citation statements)

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“…To confirm this effect on OPAA-2 activity by reducing agents, enzyme samples were incubated at 4°C in assay medium with the addition of 0.1 or 1.0 mM DTT or ,3-mercaptoethanol. After 2,6, and 18 h, the reaction mixtures were transferred to the assay vessel, brought up to temperature, and examined for activity by the addition of DFP. Both reducing agents showed a stimulatory effect, with DTT giving the greatest increase (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Cultures were grown in a medium consisting of the following (grams per liter): NaCl, 50; MgSO2 7H20, 10; Proteose Peptone (Difco), 10; yeast extract, 6; and N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES), 2.5 (pH 6.8). Inoculated flasks (4 or 6 liter) containing 1 to 1.5 liters of medium were incubated at 30 to 37°C, on a rotary shaker at 240 rpm, for 18 to 24 h. Cells were harvested by centrifugation (7,500 x g) at 20°C (to prevent precipitation of an unidentified saltlike material observed at lower temperatures) and stored at -20°C.…”

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confidence: 99%

“…OPA anhydrase activity was routinely assayed by monitoring fluoride release from DFP by an ion-specific electrode as has been described numerous times in the literature (6,7,11). Unless otherwise stated the reaction medium contained 500 mM NaCl, 50 mM Bis-Tris propane (pH 7.2), 3.0 mM DFP, 1.0 mM MnCl2 4H20, and 5 to 25 jil of enzyme sample in a total volume of 2.5 ml.…”

mentioning

confidence: 99%

“…Unless otherwise stated the reaction medium contained 500 mM NaCl, 50 mM Bis-Tris propane (pH 7.2), 3.0 mM DFP, 1.0 mM MnCl2 4H20, and 5 to 25 jil of enzyme sample in a total volume of 2.5 ml. The pH of 7.2 was selected to be the standard for all assays in order to be consistent with the numerous published reports on other OPA anhydrases (5)(6)(7)(10)(11)(12)(13). Assays were run at 25°C in a temperature-controlled vessel with stirring.…”

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Purification and properties of an organophosphorus acid anhydrase from a halophilic bacterial isolate

1991

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A moderately halophilic bacterial isolate has been found to possess high levels of enzymatic activity against several highly toxic organophosphorus compounds. The predominant enzyme, designated organophosphorus acid anhydrase 2, has been purified 1,000-fold to homogeneity and characterized. The enzyme is a single polypeptide with a molecular weight of 60,000. With diisopropylfluorophosphate as a substrate, the enzyme has optimum activity at pH 8.5 and 50 degrees C, and it is stimulated by manganese and cobalt.

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Section: Resultsmentioning

confidence: 99%

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Purification and properties of an organophosphorus acid anhydrase from a halophilic bacterial isolate

1991

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“…Hoskin (1984) stated that there appears to be two distinctly different classes of OPH. The first class is of the 'Mazur' type OPH.…”

Section: Organophosphorous Hydrolases (Oph)mentioning

confidence: 99%

Biological degradation of explosives and chemical agents

Walker

Kaplan

1992

Biodegradation

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Hazardous energetic organo-nitro compounds are found as contaminants in many environments. A series of nitro aromatics, nitrate esters and nitro amines, all characteristic of this class, has been studied for their susceptibility to biological transformation. Biotransformation pathways for each of these compounds have been identified and are summarized. Implications for these findings in light of current contamination issues is discussed. The detoxification of organophosphate chemical agents focuses on the investigation of organophosphate degrading enzymes from bacteria. Certain of these enzymes, active both in solution and when immobilized onto a solid surface, are very successful in hydrolyzing and detoxifying various organophosphate chemical agents. The relationship of this research to the critical concerns of the agricultural industry regarding detoxification of organophosphorous pesticides is discussed.

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Structural Insights into the Dual Activities of the Nerve Agent Degrading Organophosphate Anhydrolase/Prolidase

et al. 2010

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The organophosphate acid anhydrolase (OPAA) is a member of a class of bimetalloenzymes that hydrolyze a variety of toxic acetylcholinesterase-inhibiting organophosphorus compounds, including fluorine-containing chemical nerve agents. It also belongs to a family of prolidases, with significant activity against various Xaa-Pro dipeptides. Here we report the X-ray structure determination of the native OPAA (58 kDa mass) from Alteromonas sp. strain JD6.5 and its cocrystal with the inhibitor mipafox [N,N'-diisopropyldiamidofluorophosphate (DDFP)], a close analogue of the nerve agent organophosphate substrate diisopropyl fluorophosphate (DFP). The OPAA structure is composed of two domains, amino and carboxy domains, with the latter exhibiting a "pita bread" architecture and harboring the active site with the binuclear Mn(2+) ions. The native OPAA structure revealed unexpectedly the presence of a well-defined nonproteinaceous density in the active site whose identity could not be definitively established but is suggestive of a bound glycolate, which is isosteric with a glycine (Xaa) product. All three glycolate oxygens coordinate the two Mn(2+) atoms. DDFP or more likely its hydrolysis product, N,N'-diisopropyldiamidophosphate (DDP), is present in the cocrystal structure and bound by coordinating the binuclear metals and forming hydrogen bonds and nonpolar interactions with active site residues. An unusual common feature of the binding of the two ligands is the involvement of only one oxygen atom of the glycolate carboxylate and the product DDP tetrahedral phosphate in bridging the two Mn(2+) ions. Both structures provide new understanding of ligand recognition and the prolidase and organophosphorus hydrolase catalytic activities of OPAA.

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Two Enzymes for the Detoxicatlon of Organophosphorus Compounds—Sources, Similarities, and Significance

Cited by 11 publications

References 0 publications

Purification and properties of an organophosphorus acid anhydrase from a halophilic bacterial isolate

Purification and properties of an organophosphorus acid anhydrase from a halophilic bacterial isolate

Biological degradation of explosives and chemical agents

Structural Insights into the Dual Activities of the Nerve Agent Degrading Organophosphate Anhydrolase/Prolidase

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