scholarly journals Effect of metal ions and chemical agents on the activity of endoglucanase GH5 exploited from goats-rumen bacterial metagenomic DNA data

2021 ◽  
Vol 19 (3) ◽  
pp. 509-517
Author(s):  
Nguyen Khanh Hoang Viet ◽  
Ha Thi Thuy Hoa ◽  
Truong Nam Hai ◽  
Do Thi Huyen

A gene coding for GH5 endoglucanase exploited from metagnomic DNA data of bacteria in Vietnamese goats’ rumen was modularity structure including a catalytic module, a fibronectin-3 like module and an X module. The recombinant enzyme was sucessfully expressed in E. coli and purified.  To study the effect of some metal ions and chemicals on enzyme activity, in this study, we used some tools including Swiss-Prot, ProFunc, COFACTOR for prediction of enzyme structure and ligands interaction. The obtained results indicated that the most similar structure with enzyme had two conserved residues (Asp-190 và Asp-192) linked with Mn2+ within a radius of ~ 3.5 Å from the center of ion Mn2+ and enzyme molecule contained a disulphide bond. Experimental results for essessment of the effect of some metal ions (Ca2 +, Mn2 +, Mg2+, Ni2+, K+, Co2+, Cu2+, Zn2+, Fe3+) at the final concentration of 10 mM and of six common chemicals including SDS (1%), urea (1 µM), 2-mercaptoethanol (1 µM), EDTA (1 µM), tween 80 (1mM), triton X-100 (1 µM) showed that only Mn2+ increased enzyme activity slightly at concentration of 10 mM and two times at the concentration of 40 mM Mn2+. The Mn2+ has been identified as a specific binding agent may increase the stability and activity of endoglucanase GH5.

1993 ◽  
Vol 58 (2) ◽  
pp. 291-294 ◽  
Author(s):  
M. Krystyna Pawlak

The effect of electroreduction of Zn(II), Cd(II), Pb(II) and Cu(II) ions on the stability of a film of the surfactant Triton X-100 on the surface of hanging mercury drop electrode was investigated. A procedure is suggested to disturb the film in order to facilitate the determination of the above metal ions by anodic stripping voltammetry with accumulation.


2001 ◽  
Vol 64 (9) ◽  
pp. 1334-1340 ◽  
Author(s):  
KESHUN YU ◽  
MELISSA C. NEWMAN ◽  
DOUGLAS D. ARCHBOLD ◽  
THOMAS R. HAMILTON-KEMP

Survival of Escherichia coli O157:H7 was studied on strawberry, a fruit that is not usually washed during production, harvest, or postharvest handling. Two strains of the bacteria were tested separately on the fruit surface or injected into the fruit. Both strains of E. coli O157:H7 survived externally and internally at 23°C for 24 h and at 10, 5, and −20°C for 3 days. The largest reduction in bacterial population occurred at −20°C and on the fruit surface during refrigeration. In all experiments, the bacteria inside the fruit either survived as well as or better than bacteria on the surface, and ATCC 43895 frequently exhibited greater survival than did ATCC 35150. Two strains of E. coli also survived at 23°C on the surface and particularly inside strawberry fruit. Chemical agents in aqueous solution comprising NaOCl (100 and 200 ppm), Tween 80 (100 and 200 ppm), acetic acid (2 and 5%), Na3PO4 (2 and 5%), and H2O2 (1 and 3%) were studied for their effects on reduction of surface-inoculated (108 CFU/ml) E. coli O157:H7 populations on strawberry fruit. Dipping the inoculated fruit in water alone reduced the pathogen population about 0.8 log unit. None of the compounds with the exception of H2O2 exhibited more than a 2-log CFU/g reduction of the bacteria on the fruit surface. Three percent H2O2, the most effective chemical treatment, reduced the bacterial population on strawberries by about 2.2 log CFU/g.


Food Research ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 1066-1070
Author(s):  
M.M. Rahman ◽  
U.F. Shahjadee ◽  
F. Khanam ◽  
A.Z. Rupa ◽  
M.A.K. Azad

The present investigation was conducted to analyze the activity of enzymes (protease, αamylase, cellulase and urease) of selected salad vegetables (white radish, red radish, beet, carrot, papaya, cucumber and tomato) as well as to determine the effect of chemical agents and metallic salts on the stability of enzymes. Salad vegetables are one of the cheap sources of adequate vitamins, minerals and enzymes. The protease, α-amylase and cellulase activity were highest in papaya (4.11±0.21 U/g, 1.68±0.21 U/g and 0.26±0.13 U/ g) whereas the urease activity was not detected in papaya, cucumber and tomato. The protease, α-amylase and cellulase activity of papaya were increased 24.83%, 42.26% and 57.69% than cucumber while the cellulase activity of carrot was increased 44.45% than tomato. The activity of protease and α-amylase of beet were decreased 52.44%, 33.63% while the cellulase activity of beet was increased 36.36% from radish. The toxicity indicating urease enzyme activity was not detected in papaya, tomato and cucumber but negligible in radish, beet and carrot which can be nullified. The activities of enzymes were increased in the presence of metallic salts such as Ca2+, Mg2+ and Mn2+ while Fe2+, Zn2+ and Cu2+ inhibited the enzyme's activity moderately. Results revealed that in the presence of higher concentrations of urea, EDTA and acetic acid, the activities of all the enzymes were completely inhibited.


2013 ◽  
Vol 11 (2) ◽  
pp. 781-785 ◽  
Author(s):  
Rosalia Cuahtecontzi-Delint ◽  
Miguel A Mendez-Rojas ◽  
Erick R Bandala ◽  
Marco A Quiroz ◽  
Sonia Recillas ◽  
...  

Abstract CeO2 nanoparticles (NPs) were tested to assess their toxicity on Escherichia coli strain in the presence of non-ionic surfactants. The NPs were dispersed in water by sonication at different pH values and times then mixed with three different surfactants (i.e., Triton X-100, Polyvinyl Pyrrolidone (PVP) and Tween 80) with a concentration of 0.001% v/v. It was found that sonication favored dispersion of the material and produced particles having 100 nm sizes in average. The material show toxicity to E. coli at pH 7 when growth using only minimal M9 media; no toxic response was observed for bacteria growth in rich media. The toxic effect in minimal media was enhanced by adding any of the non-ionic surfactants to the media. The use of CeO2 plus surfactant decreased the minimal inhibitory concentration (MIC) value of E. coli. The highest effect was observed for addition of Tween 80, in this case MIC value was 0.150 mg mL–1 compared to 3 mg mL–1 of CeO2 alone (almost 20 times improvement). These findings suggest the importance of different substances that can interact with NPs, like surfactants, usually present in wastewater systems that may lead to undesirable unexpected toxic characteristics in materials usually considered as innocuous.


Biologia ◽  
2012 ◽  
Vol 67 (4) ◽  
Author(s):  
Ponnambalam Subhashini ◽  
Neelamegam Annamalai ◽  
Ayyappan Saravanakumar ◽  
Thangavel Balasubramanian

AbstractAn extracellular alkaline protease-producing Vibrio sp. was isolated from mangrove sediments of Vellar estuary. A 9.36-fold purification was achieved by a three-step purification procedure and the molecular weight of the enzyme was determined as 33 kDa by SDS-PAGE. The enzyme was active in a broad range of pH (6.0–11.0) and temperature (30–70°C), the optimum being at pH 9.0 and temperature 55°C. The enzyme was stable at alkaline pH range of 9–11 and up to a temperature of 60°C, after incubation for 1 h. Metals like Co2+, Hg2+, Ni2+ and Cu2+ inhibited the enzyme activity, whereas Fe2+, Ca2+ and Mn2+ were found to enhance the activity. The protease was found to be highly stable in the presence of oxidizing agents like H2O2, detergents such as SDS and Triton-X-100 and also some of the commonly used commercial detergents. The organic solvents like xylene, isopropanol, hexane and benzene were found to enhance as well as stabilize the enzyme activity. The extracellular production of the enzyme, the pH and thermal stability, and the stability in presence of oxidants, surfactants, commercial detergents and organic solvents, altogether suggest that it can be used as a laundry additive.


1996 ◽  
Vol 318 (1) ◽  
pp. 213-218 ◽  
Author(s):  
Marion LUDERER-GMACH ◽  
Hans-Dieter LIEBIG ◽  
Wolfgang SOMMERGRUBER ◽  
Tilman VOSS ◽  
Frederike FESSL ◽  
...  

The 2A proteinases of human rhinoviruses are cysteine proteinases with marked similarities to serine proteinases. In the absence of a three-dimensional structure, we developed a genetical screening system for proteolytic activity and identified Phe-130 as a key residue. The mutation Phe-130 → Tyr almost completely inhibited enzyme activity at 37 °C; activity was, however, partially restored by the following exchanges: Ser-27 → Pro, His-135 → Arg or His-137 → Arg. To investigate this phenotypic reversion, 2A proteinases with the mutations Phe-130 → Tyr, Phe-130 → Tyr/His-135 → Arg, Phe-130 → Tyr/His-137 → Arg, His-135 → Arg or His-137 → Arg were expressed in Escherichia coli and purified. None of these mutations affected the affinity of the enzyme for a peptide substrate. However, the temperature-dependence of enzyme activity, as assayed by cleavage of a peptide substrate and by monitoring the toxicity of the proteinases towards the E. coli strain BL21(DE3), and the structural stability, as monitored by 8-anilino-1-naphthalenesulphonic acid fluorescence and CD spectrometry, were affected. The thermal transition temperatures for both the activity and the stability of the Phe-130 → Tyr 2A proteinase were reduced by about 17 °C compared with the wild-type enzyme. The presence of the additional mutations His-135 → Arg or His-137 → Arg in the Phe-130 → Tyr mutant increased temperature stability by 3 °C and 6 °C respectively. Thus essential interactions exist within the C-terminal domain of human rhinoviral 2A proteinases which contribute to the overall stability and integrity of the enzyme.


2020 ◽  
pp. 15-20
Author(s):  
Ersin Yucel ◽  
Mine Yucel

In this study, the usage of the peppermint (Mentha piperita) for extracting the metal ions [Mg (II), Cr (II), Ni (II), Cu (II), Zn (II), Cd (II), Pb (II)] that exist at water was investigated. In order to analyze the stability properties, Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms were used at removing the metal ions and the highest correlation coefficients (R2) were obtained at Langmuir isotherm. Therefore, it is seen that the Langmuir model is more proper than the Freundlich model. However, it was found that the correlation coefficients of removing Ni and Cd is higher at Freundlich model than Langmuir and low at Dubinin-Radushkevich isotherm. It is established that the biosorption amount increase depends on the increase of biosorbent and it can be achieved high efficiency (95%) even with small amount (0.6 mg, peppermint extract) at lead ions. It is also determined that the peppermint extracted that is used at this study shows high biosorption capacity for metal ions and can be used for immobilization of metals from polluted areas.


Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 926
Author(s):  
Maria C. Martins ◽  
Susana F. Fernandes ◽  
Bruno A. Salgueiro ◽  
Jéssica C. Soares ◽  
Célia V. Romão ◽  
...  

Flavodiiron proteins (FDPs) are a family of modular and soluble enzymes endowed with nitric oxide and/or oxygen reductase activities, producing N2O or H2O, respectively. The FDP from Escherichia coli, which, apart from the two core domains, possesses a rubredoxin-like domain at the C-terminus (therefore named flavorubredoxin (FlRd)), is a bona fide NO reductase, exhibiting O2 reducing activity that is approximately ten times lower than that for NO. Among the flavorubredoxins, there is a strictly conserved amino acids motif, -G[S,T]SYN-, close to the catalytic diiron center. To assess its role in FlRd’s activity, we designed several site-directed mutants, replacing the conserved residues with hydrophobic or anionic ones. The mutants, which maintained the general characteristics of the wild type enzyme, including cofactor content and integrity of the diiron center, revealed a decrease of their oxygen reductase activity, while the NO reductase activity—specifically, its physiological function—was almost completely abolished in some of the mutants. Molecular modeling of the mutant proteins pointed to subtle changes in the predicted structures that resulted in the reduction of the hydration of the regions around the conserved residues, as well as in the elimination of hydrogen bonds, which may affect proton transfer and/or product release.


Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 263
Author(s):  
Fabian Schröer ◽  
Tanja J. Paul ◽  
Dimitri Wilms ◽  
Torben H. Saatkamp ◽  
Nicholas Jäck ◽  
...  

The synthesis of carbohydrate-functionalized biocompatible poly(oligo(ethylene glycol) methacrylate microgels and the analysis of the specific binding to concanavalin A (ConA) and Escherichia coli (E. coli) is shown. By using different crosslinkers, the microgels’ size, density and elastic modulus were varied. Given similar mannose (Man) functionalization degrees, the softer microgels show increased ConA uptake, possibly due to increased ConA diffusion in the less dense microgel network. Furthermore, although the microgels did not form clusters with E. coli in solution, surfaces coated with mannose-functionalized microgels are shown to bind the bacteria whereas galactose (Gal) and unfunctionalized microgels show no binding. While ConA binding depends on the overall microgels’ density and Man functionalization degree, E. coli binding to microgels’ surfaces appears to be largely unresponsive to changes of these parameters, indicating a rather promiscuous surface recognition and sufficiently strong anchoring to few surface-exposed Man units. Overall, these results indicate that carbohydrate-functionalized biocompatible oligo(ethylene glycol)-based microgels are able to immobilize carbohydrate binding pathogens specifically and that the binding of free lectins can be controlled by the network density.


2021 ◽  
Vol 9 (2) ◽  
pp. 402
Author(s):  
Hélène Michaux ◽  
Aymen Halouani ◽  
Charlotte Trussart ◽  
Chantal Renard ◽  
Hela Jaïdane ◽  
...  

Coxsackievirus B4 (CV-B4) can infect human and murine thymic epithelial cells (TECs). In a murine TEC cell line, CV-B4 can downregulate the transcription of the insulin-like growth factor 2 (Igf2) gene coding for the self-peptide of the insulin family. In this study, we show that CV-B4 infections of a murine TEC cell line decreased Igf2 P3 promoter activity by targeting a region near the transcription start site; however, the stability of Igf2 transcripts remained unchanged, indicating a regulation of Igf2 transcription. Furthermore, CV-B4 infections decreased STAT3 phosphorylation in vitro. We also showed that mice infected with CV-B4 had an altered expression of Igf2 isoforms as detected in TECs, followed by a decrease in the pro-IGF2 precursor in the thymus. Our study sheds new light on the intrathymic regulation of Igf2 transcription during CV-B4 infections and supports the hypothesis that a viral infection can disrupt central self-tolerance to insulin by decreasing Igf2 transcription in the thymic epithelium.


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