scholarly journals Improving the Catalytic Activity of HyperthermophilicPyrococcus horikoshiiProlidase for Detoxification of Organophosphorus Nerve Agents over a Broad Range of Temperatures

Archaea ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Casey M. Theriot ◽  
Rebecca L. Semcer ◽  
Saumil S. Shah ◽  
Amy M. Grunden
Keyword(s):  
Catalytic Activity ◽  
Nerve Agents ◽  
Nerve Agent ◽  
Structural Factors ◽  
Wild Type ◽  
Protein Thermostability ◽  
Pyrococcus Horikoshii ◽  
Organophosphorus Nerve Agents ◽  
Op Nerve Agents ◽  
Ph Range

Prolidases hydrolyze Xaa-Pro dipeptides and can also cleave the P-F and P-O bonds found in organophosphorus (OP) compounds, including the nerve agents soman and sarin.Ph1prol (PH0974) has previously been isolated and characterized fromPyrococcus horikoshiiand was shown to have higher catalytic activity over a broader pH range, higher affinity for metal, and increased thermostability compared toP. furiosusprolidase,Pfprol (PF1343). To obtain a better enzyme for OP nerve agent decontamination and to investigate the structural factors that may influence protein thermostability and thermoactivity, randomly mutatedPh1prol enzymes were prepared. FourPh1prol mutants (A195T/G306S-, Y301C/K342N-, E127G/E252D-, and E36V-Ph1prol) were isolated which had greater thermostability and improved activity over a broader range of temperatures against Xaa-Pro dipeptides and OP nerve agents compared to wild typePyrococcusprolidases.

scholarly journals Catalytically Active Imine-based Covalent Organic Frameworks for Detoxification of Nerve Agent Simulants in Aqueous Media

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1974 ◽  
Author(s):  
Sergio Royuela ◽  
Rodrigo Gil-San Millán ◽  
María J. Mancheño ◽  
M. Mar Ramos ◽  
José L. Segura ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Functional Groups ◽  
Aqueous Media ◽  
Nerve Agents ◽  
Nerve Agent ◽  
Covalent Organic Frameworks ◽  
Preliminary Results ◽  
Catalytically Active ◽  
Nerve Gas

A series of imine-based covalent organic frameworks decorated in their cavities with different alkynyl, pyrrolidine, and N-methylpyrrolidine functional groups have been synthetized. These materials exhibit catalytic activity in aqueous media for the hydrolytic detoxification of nerve agents, as exemplified with nerve gas simulant diisopropylfluorophosphate (DIFP). These preliminary results suggest imine-based covalent organic frameworks (COFs) as promising materials for detoxification of highly toxic molecules.

scholarly journals Review of Biomarkers and Analytical Methods for Organophosphate Pesticides and Applicability to Nerve Agents

2020 ◽  
Vol 185 (3-4) ◽  
pp. e414-e421 ◽  
Author(s):  
Jennifer Therkorn ◽  
David G Drewry ◽  
Olivia Tiburzi ◽  
Mekbib Astatke ◽  
Charles Young ◽  
...  
Keyword(s):  
Literature Review ◽  
Systematic Literature Review ◽  
Analytical Methods ◽  
English Language ◽  
Human Study ◽  
Nerve Agents ◽  
Nerve Agent ◽  
Primary Data ◽  
Pesticide Exposures ◽  
Op Nerve Agents

Abstract Introduction Recent malicious use of chemical warfare agents (CWAs) is a reminder of their severity and ongoing threat. One of the main categories of CWAs is the organophosphate (OP) nerve agents. Presently, there is an urgent need to identify and evaluate OP nerve agent biomarkers that can facilitate identification of exposed individuals post-CWA incident. While exposures to OP nerve agents may be scenario-specific, the public is commonly exposed to OP compounds through the ubiquitous use of OP pesticides, which are chemically related to nerve agents. Therefore, a systematic literature review and methodological quality assessment were conducted for OP pesticide biomarker studies to serve as a baseline to assess if these approaches may be adapted to OP nerve agent exposures. Materials and Methods We conducted a systematic literature review to identify biomarkers of OP pesticide exposures. English language studies of any design that reported primary data on biomarkers for exposures in nonhuman primates or adult human study participants were eligible for inclusion. Using standard criteria for assessing the completeness of reported analytical methods, the quality of study methods was critically evaluated. Results A total of 1,044 studies of biomarkers of OP pesticide exposure were identified, of which 75 articles satisfied the inclusion and exclusion criteria. These studies described 143 different analyte/sample matrix combinations: 99 host-based biomarkers, 28 metabolites, 12 pesticides, and 4 adducts. The most commonly reported biomarkers were dialkyl phosphate urinary metabolites (22 studies), blood acetylcholinesterase, and plasma butyrylcholinesterase (26 studies each). None of the assessed quality review criteria were fully addressed by all identified studies, with almost all criteria scoring less than 50%. Conclusion Cholinesterase activity may have utility for identifying individuals with exposures surpassing a given threshold of OP nerve agent, but further investigation of how acetylcholinesterase and butyrylcholinesterase levels correlate with observed patient symptoms may be required to ensure accuracy of results. As CWAs and nerve agents are more readily used, more standardized reporting of biomarker measurements are needed to develop new approaches for OP nerve agent biomarkers.

Catalytic Detoxification of Organophosphorus Nerve Agents by Butyrylcholinesterase-Polymer-Oxime Bioscavengers

2020 ◽  
Vol 21 (9) ◽  
pp. 3867-3877
Author(s):  
Libin Zhang ◽  
Hironobu Murata ◽  
Gabriel Amitai ◽  
Paige N. Smith ◽  
Krzysztof Matyjaszewski ◽  
...  
Keyword(s):  
Nerve Agents ◽  
Organophosphorus Nerve Agents

pH-induced hysteretic properties of phosphofructokinase purified from rat myocardium

1986 ◽  
Vol 250 (3) ◽  
pp. R505-R511 ◽  
Author(s):  
S. C. Hand ◽  
J. F. Carpenter
Keyword(s):  
Catalytic Activity ◽  
Metabolic Regulation ◽  
Inverse Correlation ◽  
Rat Myocardium ◽  
Solution Ph ◽  
Reversible Inactivation ◽  
Ph Range ◽  
Hysteretic Loss ◽  
Fructose 1,6 Bisphosphate

Phosphofructokinase (PFK) purified from the rat myocardium is reversibly inactivated under a pH regime approximating that reported for ischemic hearts. At pH 6.5 and 37 degrees C, the enzyme displays a hysteretic loss of activity during 60-min incubations, declining to 48% of control (pH 7.1, 37 degrees C) values. Citric acid increases the degree of inactivation (28% of control), whereas fructose 1,6-bisphosphate reduces the decline in activity. Simultaneous measurements of 90 decreases light scattering and catalytic activity suggest the inactivation is temporally linked to dissociation of active tetrameric enzyme into an inactive form of lower molecular weight. Fluorescence enhancement of the extrinsic probe sodium mansate, which binds preferentially to dimeric PFK, indicates that the equilibrium dimer concentration (cp1 infinity) increases as pH is lowered. This increase in cp1 infinity exhibits a strong inverse correlation (r = 0.984) with catalytic activity across the pH range of 8.0 to 6.5. Returning solution pH to 7.0 or above promotes a time-dependent reactivation and repolymerization of PFK. The rate of reactivation is increased at higher enzyme concentrations and in the presence of trimethylamine-N-oxide, a nitrogenous osmolyte noted for its ability to promote protein aggregation reactions. Thus these results demonstrate the capacity of rat heart PFK to undergo reversible inactivation and dissociation in vitro and represent the first phase of a two-part study testing the hypothesis that these pH-induced hysteretic processes are operative in the ischemic myocardium. The data are evaluated in terms of the potential roles of hysteretic enzymes in metabolic regulation.

scholarly journals Prohormone convertases 1/3 and 2 together orchestrate the site-specific cleavages of progastrin to release gastrin-34 and gastrin-17

2008 ◽  
Vol 415 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Jens F. Rehfeld ◽  
Xiaorong Zhu ◽  
Christina Norrbom ◽  
Jens R. Bundgaard ◽  
Anders H. Johnsen ◽  
...  
Keyword(s):  
Structural Factors ◽  
Cleavage Sites ◽  
Wild Type ◽  
Prohormone Convertases ◽  
Site Specific ◽  
G Cells ◽  
Processing Site ◽  
Vitro Effect

Cellular synthesis of peptide hormones requires PCs (prohormone convertases) for the endoproteolysis of prohormones. Antral G-cells synthesize the most gastrin and express PC1/3, 2 and 5/6 in the rat and human. But the cleavage sites in progastrin for each PC have not been determined. Therefore, in the present study, we measured the concentrations of progastrin, processing intermediates and α-amidated gastrins in antral extracts from PC1/3-null mice and compared the results with those in mice lacking PC2 and wild-type controls. The expression of PCs was examined by immunocytochemistry and in situ hybridization of mouse G-cells. Finally, the in vitro effect of recombinant PC5/6 on progastrin and progastrin fragments containing the relevant dibasic cleavage sites was also examined. The results showed that mouse G-cells express PC1/3, 2 and 5/6. The concentration of progastrin in PC1/3-null mice was elevated 3-fold. Chromatography showed that cleavage of the Arg36Arg37 and Arg73Arg74 sites were grossly decreased. Accordingly, the concentrations of progastrin products were markedly reduced, α-amidated gastrins (-34 and -17) being 25% of normal. Lack of PC1/3 was without effect on the third dibasic site (Lys53Lys54), which is the only processing site for PC2. Recombinant PC5/6 did not cleave any of the dibasic processing sites in progastrin and fragments containing the relevant dibasic processing sites. The complementary cleavages of PC1/3 and 2, however, suffice to explain most of the normal endoproteolysis of progastrin. Moreover, the results show that PCs react differently to the same dibasic sequences, suggesting that additional structural factors modulate the substrate specificity.

scholarly journals GUCY2D Gene Loss-of-Function Mutations Responsible for Leber Congenital Amaurosis 1

2019 ◽  
Author(s):  
Feng Xue ◽  
Tianying Wei ◽  
Junhui Sun ◽  
Yuqin Luo ◽  
Yanan Huo ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Guanylate Cyclase ◽  
Cyclic Guanosine Monophosphate ◽  
Guanosine Monophosphate ◽  
Loss Of Function ◽  
Wild Type ◽  
Leber Congenital Amaurosis ◽  
Cellular Location ◽  
Next Generation Sequencing Ngs ◽  
Generation Sequencing

Abstract Background: Leber congenital amaurosis (LCA) is a group of severe congenital neurodegenerative diseases. Variants in guanylate cyclase 2D (GUCY2D), which encoded guanylate cyclase protein (ROS-GC1) associate with LCA1, accounting for 6–21% of all LCA cases. Methods: In this study, one family with LCA1 was recruited from China. A combination of next-generation sequencing (NGS) and Sanger sequencing was used for disease-causing mutations screening. Additionally, immunohistochemistry and HPLC-coupled tandem mass-spectrometry (HPLC-MS/MS) were used to confirm the cellular location and catalytic activity of ROS-GC1 mutants, respectively. Results: We found three novel mutations (c.139_139delC, c.835G>A and c.2783G>A) in GUCY2D gene. The results showed that mutation c.139_139delC results in a truncated protein and destroys the structure of ROS-GC1 protein. Mutations c.835G>A and c.2783G>A exert no effects on cellular location, whereas significantly reduce the catalytic activity of ROS-GC1. Conclusions: Our findings highlight the clinical range of LCA. Moreover we used HPLC-MS/MS to analyze the concentration of 3', 5'-cyclic guanosine monophosphate (cGMP), suggesting that HPLC-MS/MS can be an effective alternative method to evaluate the catalytic activity of wild type (wt) and mutant ROS-GC1.

scholarly journals Hydrolysis of Methionine- and Histidine-Containing Peptides Promoted by Dinuclear Platinum(II) Complexes with Benzodiazines as Bridging Ligands: Influence of Ligand Structure on the Catalytic Ability of Platinum(II) Complexes

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Snežana Rajković ◽  
Beata Warżajtis ◽  
Marija D. Živković ◽  
Biljana Đ. Glišić ◽  
Urszula Rychlewska ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Amide Bond ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
Bridging Ligands ◽  
Metal Centers ◽  
H Nmr ◽  
Dinuclear Platinum ◽  
Ph Range ◽  
Hydrolysis Of

Dinuclear platinum(II) complexes, [{Pt(en)Cl}2(μ-qx)]Cl2·2H2O (1), [{Pt(en)Cl}2(μ-qz)](ClO4)2(2), and [{Pt(en)Cl}2(μ-phtz)]Cl2·4H2O (3), were synthesized and characterized by different spectroscopic techniques. The crystal structure of1was determined by single-crystal X-ray diffraction analysis, while the DFT M06-2X method was applied in order to optimize the structures of1–3. The chlorido Pt(II) complexes1–3were converted into the corresponding aqua species1a–3a, and their reactions with an equimolar amount of Ac–L–Met–Gly and Ac–L–His–Gly dipeptides were studied by1H NMR spectroscopy in the pH range 2.0 < pH < 2.5 at 37°C. It was found that, in all investigated reactions with the Ac–L–Met–Gly dipeptide, the cleavage of the Met–Gly amide bond had occurred, but complexes2aand3ashowed lower catalytic activity than1a. However, in the reactions with Ac–L–His–Gly dipeptide, the hydrolysis of the amide bond involving the carboxylic group of histidine was observed only with complex1a. The observed disparity in the catalytic activity of these complexes is thought to be due to different relative positioning of nitrogen atoms in the bridging qx, qz, and phtz ligands and consequent variation in the intramolecular separation of the two platinum(II) metal centers.

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