Dataset Information

Hydrolysis and enzymatic degradation of Novichok nerve agents.

ABSTRACT: Several parameters of the Novichok nerve agents A230, A232 and A234 were determined. Hydrolysis rates were approximately one to three orders of magnitude slower than G-type nerve agents and approximately zero to two orders of magnitude slower than V-type nerve agents. A230 was the most labile Novichok compound followed by A232 then A234. Activation energies (Ea) and frequency factors (A) were determined for all three compounds. The organophosphorus acid anhydrolase (OPAA) enzyme had catalytic efficiencies on the Novichok compounds ranging between 104 and 105 M-1 min-1 with the highest k cat/Km value for A230, then A232 and lastly, A234.

SUBMITTER: Harvey SP

PROVIDER: S-EPMC7002793 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Hydrolysis and enzymatic degradation of Novichok nerve agents.

Harvey Steven P SP McMahon Leslie R LR Berg Frederic J FJ

Heliyon 20200107 1

Several parameters of the Novichok nerve agents A230, A232 and A234 were determined. Hydrolysis rates were approximately one to three orders of magnitude slower than G-type nerve agents and approximately zero to two orders of magnitude slower than V-type nerve agents. A230 was the most labile Novichok compound followed by A232 then A234. Activation energies (E<sub>a</sub>) and frequency factors (A) were determined for all three compounds. The organophosphorus acid anhydrolase (OPAA) enzyme had c ...[more]

PMID: 32042950

Similar Datasets

Project description:Phosphotriesterase (PTE) from soil bacteria is known for its ability to catalyze the detoxification of organophosphate pesticides and chemical warfare agents. Most of the organophosphate chemical warfare agents are a mixture of two stereoisomers at the phosphorus center, and the S(P)-enantiomers are significantly more toxic than the R(P)-enantiomers. In previous investigations, PTE variants were created through the manipulation of the substrate binding pockets and these mutants were shown to have greater catalytic activities for the detoxification of the more toxic S(P)-enantiomers of nerve agent analogues for GB, GD, GF, VX, and VR than the less toxic R(P)-enantiomers. In this investigation, alternate strategies were employed to discover additional PTE variants with significant improvements in catalytic activities relative to that of the wild-type enzyme. Screening and selection techniques were utilized to isolate PTE variants from randomized libraries and site specific modifications. The catalytic activities of these newly identified PTE variants toward the S(P)-enantiomers of chromophoric analogues of GB, GD, GF, VX, and VR have been improved up to 15000-fold relative to that of the wild-type enzyme. The X-ray crystal structures of the best PTE variants were determined. Characterization of these mutants with the authentic G-type nerve agents has confirmed the expected improvements in catalytic activity against the most toxic enantiomers of GB, GD, and GF. The values of k(cat)/K(m) for the H257Y/L303T (YT) mutant for the hydrolysis of GB, GD, and GF were determined to be 2 × 10(6), 5 × 10(5), and 8 × 10(5) M(-1) s(-1), respectively. The YT mutant is the most proficient enzyme reported thus far for the detoxification of G-type nerve agents. These results support a combinatorial strategy of rational design and directed evolution as a powerful tool for the discovery of more efficient enzymes for the detoxification of organophosphate nerve agents.

Project description:BackgroundGalactoglucomannan (GGM) is the most abundant hemicellulose in softwood, and consists of a backbone of mannose and glucose units, decorated with galactose and acetyl moieties. GGM can be hydrolyzed into fermentable sugars, or used as a polymer in films, gels, and food additives. Endo-β-mannanases, which can be found in the glycoside hydrolase families 5 and 26, specifically cleave the mannan backbone of GGM into shorter oligosaccharides. Information on the activity and specificity of different mannanases on complex and acetylated substrates is still lacking. The aim of this work was to evaluate and compare the modes of action of two mannanases from Cellvibrio japonicus (CjMan5A and CjMan26A) on a variety of mannan substrates, naturally and chemically acetylated to varying degrees, including naturally acetylated spruce GGM. Both enzymes were evaluated in terms of cleavage patterns and their ability to accommodate acetyl substitutions.ResultsCjMan5A and CjMan26A demonstrated different substrate preferences on mannan substrates with distinct backbone and decoration structures. CjMan5A action resulted in higher amounts of mannotriose and mannotetraose than that of CjMan26A, which mainly generated mannose and mannobiose as end products. Mass spectrometric analysis of products from the enzymatic hydrolysis of spruce GGM revealed that an acetylated hexotriose was the shortest acetylated oligosaccharide produced by CjMan5A, whereas CjMan26A generated acetylated hexobiose as well as diacetylated oligosaccharides. A low degree of native acetylation did not significantly inhibit the enzymatic action. However, a high degree of chemical acetylation resulted in decreased hydrolyzability of mannan substrates, where reduced substrate solubility seemed to reduce enzyme activity.ConclusionsOur findings demonstrate that the two mannanases from C. japonicus have different cleavage patterns on linear and decorated mannan polysaccharides, including the abundant and industrially important resource spruce GGM. CjMan26A released higher amounts of fermentable sugars suitable for biofuel production, while CjMan5A, producing higher amounts of oligosaccharides, could be a good candidate for the production of oligomeric platform chemicals and food additives. Furthermore, chemical acetylation of mannan polymers was found to be a potential strategy for limiting the biodegradation of mannan-containing materials.

Dataset Information

Hydrolysis and enzymatic degradation of Novichok nerve agents.

Publications

Hydrolysis and enzymatic degradation of Novichok nerve agents.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets