Giardiasis, which is caused by Giardia lamblia infection, is a relevant cause of morbidity and mortality worldwide. Because no vaccines are currently available to treat giardiasis, chemotherapeutic ...drugs are the main options for controlling infection. Evidence has shown that the nitro drug nitazoxanide (NTZ) is a commonly prescribed treatment for giardiasis; however, the mechanisms underlying NTZ’s antigiardial activity are not well-understood. Herein, we identified the glucose-6-phosphate::6-phosphogluconate dehydrogenase (GlG6PD::6PGL) fused enzyme as a nitazoxanide target, as NTZ behaves as a GlG6PD::6PGL catalytic inhibitor. Furthermore, fluorescence assays suggest alterations in the stability of GlG6PD::6PGL protein, whereas the results indicate a loss of catalytic activity due to conformational and folding changes. Molecular docking and dynamic simulation studies suggest a model of NTZ binding on the active site of the G6PD domain and near the structural NADPsup.+ binding site. The findings of this study provide a novel mechanistic basis and strategy for the antigiardial activity of the NTZ drug.
Generally, there are scant data about the constituents and eventually the biological activity of essential oils (EOs) from aromatic plants that grow naturally in Sudan. The present study aimed to ...determine the chemical composition, and antioxidant and enzyme inhibitory activities of EO extracted from the fruit of Chamaecyparis obtusa (Siebold and Zucc.) Endl. (family Cupressaceae), root of Chrysopogon nigritanus (Benth.) Veldkampis (family Poaceae) and aerial part of Lavandula coronopifolia Poir (family Lamiaceae). The fruit of C. obtusa contained only monoterpenes, mainly hydrogenated ones, with α-pinene (69.07%) as the major component. Oxygenated sesquiterpenes comprised the highest content of the C. nigritanus root EO with cedr-8-en-15-ol (28.69%) as the major constituent while aerial parts of L. coronopifolia contained both monoterpenes and sesquiterpenes and the oxygenated monoterpene lavandulol (26.56%) as dominant compounds. The EO of the root of C. nigritanus significantly displayed (p < 0.05) the highest anti-DPPH radical, Fesup.3+- and Cusup.2+-reducing and metal-chelating activities, while that of C. obtusa fruit significantly exerted (p < 0.05) the best anti-ABTS radical and total antioxidant activity. The two EOs significantly exhibited (p < 0.05) the highest anti-acetylcholinesterase and -butyrylcholinesterase activities, respectively, while EO of L. coronopifolia was the only oil to show a considerable inhibitory effect against the tyrosinase and α-glucosidase enzymes. In conclusion, EOs from these three plants could be natural agents with promising functional properties for food, cosmetics, and pharmaceutical applications.
α-Galactosidase (EC 3.2.1.22) refers to a group of enzymes that hydrolyze oligosaccharides containing α-galactoside-banded glycosides, such as stachyose, raffinose, and verbascose. These enzymes also ...possess great potential for application in sugar production, and in the feed and pharmaceutical industries. In this study, a strain of Lactosphaera pasteurii (WHPC005) that produces α-galactosidase was identified from the soil of Western Hunan, China. It was determined that the optimal temperature and pH for this α-galactosidase were 45 °C and 5.5, respectively. The activity of α-galactosidase was inhibited by Ksup.+, Alsup.3+, Fesup.3+, fructose, sucrose, lactose, galactose, SDS, EDTA, NaCl, and (NHsub.4)sub.2SOsub.4, and enhanced by Casup.2+, Fesup.2+, Mnsup.2, Znsup.2+, glucose, and raffinose. The optimal inducer was raffinose, and the optimal induction concentration was 30 μmol/L. The α-galactosidase gene was cloned using random fragment cloning methods. Sequence analysis demonstrated that the open reading frame of the α-galactosidase gene was 1230 bp, which encodes a putative protein of 409 amino acids in length. Bioinformatics analysis showed that the isoelectric point and molecular weight of this α-galactosidase were 4.84 and 47.40 kD, respectively. Random coils, alpha helixes, and beta turns were observed in its secondary structure, and conserved regions were found in the tertiary structure of this α-galactosidase. Therefore, this α-galactosidase-producing bacterial strain has the potential for application in the feed industry.
PI3Kgamma is a critical immune signaling enzyme activated downstream of diverse cell surface molecules, including Ras, PKCbeta activated by the IgE receptor, and Gbetagamma subunits released from ...activated GPCRs. PI3Kgamma can form two distinct complexes, with the p110gamma catalytic subunit binding to either a p101 or p84 regulatory subunit, with these complexes being differentially activated by upstream stimuli. Here, using a combination of cryo electron microscopy, HDX-MS, and biochemical assays, we have identified novel roles of the helical domain of p110gamma in regulating lipid kinase activity of distinct PI3Kgamma complexes. We defined the molecular basis for how an allosteric inhibitory nanobody potently inhibits kinase activity through rigidifying the helical domain and regulatory motif of the kinase domain. The nanobody did not block either p110gamma membrane recruitment or Ras/Gbetagamma binding, but instead decreased ATP turnover. We also identified that p110gamma can be activated by dual PKCbeta helical domain phosphorylation leading to partial unfolding of an N-terminal region of the helical domain. PKCbeta phosphorylation is selective for p110gamma-p84 compared to p110gamma-p101, driven by differential dynamics of the helical domain of these different complexes. Nanobody binding prevented PKCbeta-mediated phosphorylation. Overall, this work shows an unexpected allosteric regulatory role of the helical domain of p110gamma that is distinct between p110gamma-p84 and p110gamma-p101 and reveals how this can be modulated by either phosphorylation or allosteric inhibitory binding partners. This opens possibilities of future allosteric inhibitor development for therapeutic intervention.
Escherichia coli phytase (AppA) is widely used as an exogenous enzyme in monogastric animal feed mainly because of its ability to degrade phytic acid or its salt (phytate), a natural source of ...phosphorus. Currently, successful recombinant production of soluble AppA has been achieved by gene overexpression using both bacterial and yeast systems. However, some methods for the biomembrane immobilization of phytases (including AppA), such as surface display on yeast cells and bacterial spores, have been investigated to avoid expensive enzyme purification processes. This study explored a homologous protein production approach for displaying AppA on the cell surface of E. coli by engineering its outer membrane (OM) for extracellular expression. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of total bacterial lysates and immunofluorescence microscopy of non-permeabilized cells revealed protein expression, whereas activity assays using whole cells or OM fractions indicated functional enzyme display, as evidenced by consistent hydrolytic rates on typical substrates (i.e., p-nitrophenyl phosphate and phytic acid). Furthermore, the in vitro results obtained using a simple method to simulate the gastrointestinal tract of poultry suggest that the whole-cell biocatalyst has potential as a feed additive. Overall, our findings support the notion that biomembrane-immobilized enzymes are reliable for the hydrolysis of poorly digestible substrates relevant to animal nutrition.
A portable sensor for visual monitoring of Fe.sup.2+ and H.sub.2O.sub.2, two-dimensional Co.sub.3O.sub.4 modified by nano-IrO.sub.2 (IrO.sub.2@2D Co.sub.3O.sub.4) was prepared in this work, for the ...first time, with the help of microwave radiation at 140 °C, which was further stabilized onto common test strips. The present IrO.sub.2@2D Co.sub.3O.sub.4 possessed superior dual-function enzyme-like activity with low toxicity and excellent biocompatibility. Especially, trace Fe.sup.2+ and H.sub.2O.sub.2 could exclusively alter their enzyme-like catalytic activity with discriminating hyperchromic or hypochromic effect, i.e., from blue to colorless or to dark blue for both IrO.sub.2@2D Co.sub.3O.sub.4 dispersion and its functionalized test strips. The linear regression equations were A.sub.652 = 0.5940 - 0.00041 c.sub.Fe.sup.2+ (10.sup.-8 M, R.sup.2 = 0.9927) for Fe.sup.2+ and âA.sub.652 = 0.0023 c.sub.H2O2 + 0.00025 (10.sup.-7 M, R.sup.2 = 0.9982) for H.sub.2O.sub.2, respectively. When applied to visual monitoring of aqueous Fe.sup.2+ and intercellular H.sub.2O.sub.2, the recoveries were 101.2 ~ 102.5% and 95.8 ~ 103.7% with detection limits of 1.25 x 10.sup.-8 mol/L and 1.02 x 10.sup.-7 mol/L, respectively, far below the permitted values in drinking water set by the World Health Organization. The mechanisms for the enhancing enzyme-mimetic activity of IrO.sub.2@2D Co.sub.3O.sub.4 and its selective responses to Fe.sup.2+ and H.sub.2O.sub.2 were investigated in detail. Graphical
Introduction to the Special Issue Çadirci Efeli, Bilge Hilal; Binay, Baris; Berliner, Lawrence J
The protein journal,
04/2023, Letnik:
42, Številka:
2
Journal Article
Nanomaterials that exhibit enzyme-like activity (nanozymes) have attracted significant attention due to their potential for applications in analytical tests and in the biological field. In this ...study, an enzyme-like nanomaterial is developed by coupling Pt nanoparticles with WO.sub.2.72 (Pt/WO.sub.2.72). The resultant nanocomposite nanomaterial exhibits peroxidase activity and catalase activity. Moreover, owing to the presence of W.sup.6+ and W.sup.5+ in WO.sub.2.72, Pt/WO.sub.2.72 nanoplates demonstrate promise as scavengers of hydroxyl radicals. The Pt/WO.sub.2.72 composite nanoplates exhibit excellent peroxidase-like activity for the sensitive colorimetric detection of H.sub.2O.sub.2 and blood glucose. These Pt/WO.sub.2.72 nanoplates are thought to be a promising tool for broad potential applications in biomedicine, biotechnology, and environmental chemistry.
