scholarly journals Stabilization of b-Glucuronidase by Immobilization in Magnetic-Silica Hybrid Supports

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 669
Author(s):  
Sonali Correa ◽  
Magdalena Ripoll ◽  
Erienne Jackson ◽  
Valeria Grazú ◽  
Lorena Betancor
Keyword(s):  
Residual Activity ◽  
Covalent Attachment ◽  
Hydrodynamic Diameter ◽  
Individual Effect ◽  
Soluble Enzyme ◽  
Initial Activity ◽  
Magnetic Silica ◽  
Low Probability ◽  
The Individual ◽  
Silica Hybrid

β-Glucuronidases are a class of enzymes that catalyze the breakdown of complex carbohydrates. They have well documented biocatalytic applications in synthesis, therapeutics, and analytics that could benefit from enzyme immobilization and stabilization. In this work, we have explored a number of immobilization strategies for Patella vulgata β-Glucuronidase that comprised a tailored combination of biomimetic silica (Si) and magnetic nanoparticles (MNPs). The individual effect of each material on the enzyme upon immobilization was first tested. Three different immobilization strategies for covalent attachment on MNPs and different three catalysts for the deposition of Si particles were tested. We produced nine different immobilized preparations and only two of them presented negligible activity. All the preparations were in the micro-sized range (from 1299 ± 52 nm to 2101 ± 67 nm of hydrodynamic diameter). Their values for polydispersity index varied around 0.3, indicating homogeneous populations of particles with low probability of agglomeration. Storage, thermal, and operational stability were superior for the enzyme immobilized in the composite material. At 80 °C different preparations with Si and MNPs retained 40% of their initial activity after 6 h of incubation whereas the soluble enzyme lost 90% of its initial activity within 11 min. Integration of MNPs provided the advantage of reusing the biocatalyst via magnetic separation up to six times with residual activity. The hybrid material produced herein demonstrated its versatility and robustness as a support for β-Glucuronidases immobilization.

scholarly journals Preparation of Stable Cross-Linked Enzyme Aggregates (CLEAs) of a Ureibacillus thermosphaericus Esterase for Application in Malathion Removal from Wastewater

Catalysts ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 154 ◽  
Author(s):  
Yuliya Samoylova ◽  
Ksenia Sorokina ◽  
Alexander Piligaev ◽  
Valentin Parmon
Keyword(s):  
Response Surface Methodology ◽  
Bovine Serum Albumin ◽  
High Stability ◽  
Municipal Wastewater ◽  
Maximal Activity ◽  
Cross Linking ◽  
Soluble Enzyme ◽  
Initial Activity ◽  
E Coli ◽  
Ureibacillus Thermosphaericus

In this study, the active and stable cross-linked enzyme aggregates (CLEAs) of the thermostable esterase estUT1 of the bacterium Ureibacillus thermosphaericus were prepared for application in malathion removal from municipal wastewater. Co-expression of esterase with an E. coli chaperone team (KJE, ClpB, and ELS) increased the activity of the soluble enzyme fraction up to 200.7 ± 15.5 U mg−1. Response surface methodology (RSM) was used to optimize the preparation of the CLEA-estUT1 biocatalyst to maximize its activity and minimize enzyme loss. CLEA-estUT1 with the highest activity of 29.4 ± 0.5 U mg−1 (90.6 ± 2.7% of the recovered activity) was prepared with 65.1% (w/v) ammonium sulfate, 120.6 mM glutaraldehyde, and 0.2 mM bovine serum albumin at 5.1 h of cross-linking. The biocatalyst has maximal activity at 80 °С and pH 8.0. Analysis of the properties of CLEA-estUT1 and free enzyme at 50–80 °C and pH 5.0–10.0 showed higher stability of the biocatalyst. CLEA-estUT1 showed marked tolerance against a number of chemicals and high operational stability and activity in the reaction of malathion hydrolysis in wastewater (up to 99.5 ± 1.4%). After 25 cycles of malathion hydrolysis at 37 °С, it retained 55.2 ± 1.1% of the initial activity. The high stability and reusability of CLEA-estUT1 make it applicable for the degradation of insecticides.

scholarly journals Laccase Immobilisation on Mesostructured Silicas

2012 ◽  
Vol 33 (4) ◽  
pp. 611-620 ◽  
Author(s):  
Jolanta Bryjak ◽  
Katarzyna Szymańska ◽  
Andrzej B. Jarzębski
Keyword(s):  
Thermal Inactivation ◽  
Mesoporous Silicas ◽  
Native Enzyme ◽  
Covalent Attachment ◽  
Initial Activity ◽  
Ordered Mesoporous ◽  
Extracellular Laccase ◽  
Activity Loss ◽  
Activity Decay ◽  
Hexagonally Ordered

Extracellular laccase produced by the wood-rotting fungus Cerrena unicolor was immobilised covalently on the mesostructured siliceous foam (MCF) and three hexagonally ordered mesoporous silicas (SBA-15) with different pore sizes. The enzyme was attached covalently via glutaraldehyde (GLA) or by simple adsorption and additionally crosslinked with GLA. The experiments indicated that laccase bound by covalent attachment remains very active and stable. The best biocatalysts were MCF and SBA-15 with Si-F moieties on their surface. Thermal inactivation of immobilised and native laccase at 80°C showed a biphasic-type activity decay, that could be modelled with 3- parameter isoenzyme model. It appeared that immobilisation did not significantly change the mechanism of activity loss but stabilised a fraction of a stable isoform. Examination of time needed for 90% initial activity loss revealed that immobilisation prolonged that time from 8 min (native enzyme) up to 155 min (SBA-15SF).

Innovative Experimental Investigation on the Influences of the Reynolds Number

2017 ◽  
Author(s):  
Jian Gu ◽  
Antonio Carlos Fernandes
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Dimensionless Parameter ◽  
Individual Effect ◽  
Vortex Induced Vibration ◽  
Industry Standards ◽  
Experimental Facilities ◽  
The Individual

The influences of Re (Reynolds number) on the response of vortex induced vibration (VIV) have been studied by previous researches, which indicate the influences should not be ignored. However, due to the limitation of experimental facilities and complexity of the cases, the explicit influence of Re on VIV is still not fully known. Meanwhile, the industry standards also do not supply design reference taking account of Re effects quantitatively. In present work, an innovative dimensionless parameter (denoted as “inertia-viscosity”) is proposed to displace the Re in the dimensionless system, in order to clarify the individual effect of Re. With this method, comparing tests are concisely carried out, and the effectiveness and feasibility are demonstrated. Through the comparing of tests, several remarkable results are obtained.

scholarly journals Speciation Theory of Carcinogenesis Explains Karyotypic Individuality and Long Latencies of Cancers

Genes ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 402 ◽  
Author(s):  
Ankit Hirpara ◽  
Mathew Bloomfield ◽  
Peter Duesberg
Keyword(s):  
Chromosomal Instability ◽  
Normal Cell ◽  
Neoplastic Transformation ◽  
Single Step ◽  
Chain Reactions ◽  
Mutation Theory ◽  
Normal Human ◽  
Low Probability ◽  
Carcinogen Exposure ◽  
The Individual

It has been known for over 100 years that cancers have individual karyotypes and arise only years to decades after initiating carcinogens. However, there is still no coherent theory to explain these definitive characteristics of cancer. The prevailing mutation theory holds that cancers are late because the primary cell must accumulate 3–8 causative mutations to become carcinogenic and that mutations, which induce chromosomal instability (CIN), generate the individual karyotypes of cancers. However, since there is still no proven set of mutations that transforms a normal to a cancer cell, we have recently advanced the theory that carcinogenesis is a form of speciation. This theory predicts carcinogens initiate cancer by inducing aneuploidy, which automatically unbalances thousands of genes and thus catalyzes chain-reactions of progressive aneuploidizations. Over time, these aneuploidizations have two endpoints, either non-viable karyotypes or very rarely karyotypes of new autonomous and immortal cancers. Cancer karyotypes are immortalized despite destabilizing congenital aneuploidy by clonal selections for autonomy—similar to those of conventional species. This theory predicts that the very low probability of converting the karyotype of a normal cell to that of a new autonomous cancer species by random aneuploidizations is the reason for the karyotypic individuality of new cancers and for the long latencies from carcinogens to cancers. In testing this theory, we observed: (1) Addition of mutagenic and non-mutagenic carcinogens to normal human and rat cells generated progressive aneuploidizations months before neoplastic transformation. (2) Sub-cloning of a neoplastic rat clone revealed heritable individual karyotypes, rather than the non-heritable karyotypes predicted by the CIN theory. (3) Analyses of neoplastic and preneoplastic karyotypes unexpectedly identified karyotypes with sets of 3–11 new marker chromosomes without detectable intermediates, consistent with single-step origins. We conclude that the speciation theory explains logically the long latencies from carcinogen exposure and the individuality of cancers. In addition, the theory supports the single-step origins of cancers, because karyotypic autonomy is all-or-nothing. Accordingly, we propose that preneoplastic aneuploidy and clonal neoplastic karyotypes provide more reliable therapeutic indications than current analyses of thousands of mutations.

scholarly journals Expression and Characterization of a Dye-Decolorizing Peroxidase from Pseudomonas Fluorescens Pf0-1

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 463 ◽  
Author(s):  
Nikola Lončar ◽  
Natalija Drašković ◽  
Nataša Božić ◽  
Elvira Romero ◽  
Stefan Simić ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Pseudomonas Fluorescens ◽  
Alginate Beads ◽  
Sequence Information ◽  
Soluble Enzyme ◽  
Initial Activity ◽  
Alternative Substrate ◽  
65 H ◽  
Genome Sequence Information

The consumption of dyes is increasing worldwide in line with the increase of population and demand for clothes and other colored products. However, the efficiency of dyeing processes is still poor and results in large amounts of colored effluents. It is desired to develop a portfolio of enzymes which can be used for the treatment of colored wastewaters. Herein, we used genome sequence information to discover a dye-decolorizing peroxidase (DyP) from Pseudomonas fluorescens Pf-01. Two genes putatively encoding for DyPs were identified in the respective genome and cloned for expression in Escherichia coli, of which one (PfDyP B2) could be overexpressed as a soluble protein. PfDyP B2 shows some typical features known for DyPs which includes the ability to convert dyes at the expense of hydrogen peroxide. Interestingly, t-butyl hydroperoxide could be used as an alternative substrate to hydrogen peroxide. Immobilization of PfDyP B2 in calcium-alginate beads resulted in a significant increase in stability: PfDyP B2 retains 80% of its initial activity after 2 h incubation at 50 °C, while the soluble enzyme is inactivated within minutes. PfDyP B2 was also tested with aniline and ethyl diazoacetate as substrates. Based on GC-MS analyses, 30% conversion of the starting material was achieved after 65 h at 30 °C. Importantly, this is the first report of a DyP-catalyzed insertion of a carbene into an N-H bond.

scholarly journals Peroxidase from peach fruit: thermal Stability

1998 ◽  
Vol 41 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Valdir Augusto Neves ◽  
E. J. Lourenço
Keyword(s):  
Sucrose Concentration ◽  
Residual Activity ◽  
Deae Cellulose ◽  
Heat Stability ◽  
Initial Activity ◽  
Fast Inactivation ◽  
Peach Fruit ◽  
Optimum Ph ◽  
Calculated Activation Energy ◽  
Calculated Activation

Peroxidase from peach fruit was purified 28.9-fold by DEAE-cellulose, Sephadex G-100 and hydroxylapatite chromatography. The purified enzyme showed only one peak of activity with an optimum pH of 5.0 and temperature of 40ºC. The calculated activation energy (Ea) for the reaction was 7.97 kcal/mol. The enzyme was heat-labile in the temperature range of 60 to 80ºC with a fast inactivation at 80ºC. PAGE of the inactivation course at 70ºC showed only one band of activity. Different sugars increased the heat stability of the activity in the following order: sucrose>lactose>glucose>fructose. Measurement of residual activity showed a stabilizing effect of sucrose at various temperature/sugar concentrations (10 to 40%, w/w) with the Ea for inactivation increasing with sucrose concentration from 0 to 20% (w/w). After inactivation at 70ºC and 75ºC the enzyme was able to be reactivated by up to 40% of the initial activity when stored at 30ºC.

Carbodiimide for Covalent α-Amylase Immobilization onto Magnetic Nanoparticles

2017 ◽  
Vol 16 (05n06) ◽  
pp. 1750015 ◽  
Author(s):  
Zeinab Mortazavi Milani ◽  
Razieh Jalal ◽  
Elaheh K. Goharshadi
Keyword(s):  
Residual Activity ◽  
Maximum Activity ◽  
Covalent Attachment ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Operational Conditions ◽  
Transmission Electron ◽  
Repeated Batch ◽  
Repeated Use ◽  
Co Precipitation

Covalent cross-linking of enzymes to magnetite (Fe3O4) nanoparticles (MNPs) is one of the useful enzyme immobilization methods which provides repeated use of the catalyst, facilitates enzyme separation from the reaction mixture, and sometimes improves biocatalysts stability. The aim of this study was to immobilize [Formula: see text]-amylase onto MNPs via covalent attachment using carbodiimide (CDI) molecules. MNPs were synthesized by the co-precipitation method. The size and the structure of the particles were characterized by X-ray diffraction and transmission electron microscopy. The effects of different operational conditions of direct [Formula: see text]-amylase binding on MNPs in the presence of CDI were investigated by using the shaking method. Fourier transform infrared spectroscopy was used to confirm the success of immobilization. The optimum conditions and catalytic properties of immobilized [Formula: see text]-amylase were also evaluated. The efficiency of immobilization and the residual activity of the immobilized [Formula: see text]-amylase were dependent on the mass ratio of MNPs: CDI: [Formula: see text]-amylase and the immobilization temperature. The optimum pH for the free and immobilized amylase was 6. The free and immobilized [Formula: see text]-amylase showed maximum activity at 20[Formula: see text]C and 35[Formula: see text]C, respectively. The immobilized [Formula: see text]-amylase was more thermostable than the free one. The retained activity for free [Formula: see text]-amylase after 19 storage days was 57.7% whereas it was 100% for the immobilized [Formula: see text]-amylase. In repeated batch experiments, the immobilized [Formula: see text]-amylase retained a residual activity of 45% after 11 repeated uses. The [Formula: see text] and [Formula: see text] values for the immobilized enzyme were larger than those of the free enzyme. The immobilization of [Formula: see text]-amylase on MNPs using CDI improves its stability and reusability.

Effect of Zinc Dithiocarbamates on NR Vulcanization Accelerated by Thiocarbamyl Sulfenamides and Dibenzothiazyl Disulfide

1986 ◽  
Vol 59 (1) ◽  
pp. 27-39 ◽  
Author(s):  
Rabindra Nath Datta ◽  
Dipak Kumar Basu
Keyword(s):  
Retention Time ◽  
Vital Role ◽  
The Other ◽  
Initial Part ◽  
Individual Effect ◽  
Experimental Conditions ◽  
Retarding Effect ◽  
Early Reaction ◽  
The Individual

Abstract The hplc studies with all their limitations have been employed to obtain information regarding the vulcanization of rubber accelerated by CTOS and MBTS in the early part of the reaction. It is noticed that even in the initial part of the induction period (the scorch safety, t2, of the recipe is 10.5 min), CTOS and MBTS react so rapidly with each other and also with rubber that at the end of 10 min we could detect only MBT, while the concentration of the other components formed in the reaction—namely, CTOS, OBTS, CPTD, BPTD, PMTU, CPTM, BPTM, etc.—decreased to an extremely low level. We noticed that under the experimental conditions, OBTS and CPTU have the same retention time. This naturally obscures the path for understanding the individual effect of these accelerators. The sharp disappearance of OBTS, associated with the abundant formation of MBT and nonavailability of CPTU (from CPTD, Figure 11b), gives testimony to the fact that the unsymmetrical thiourea (PMTU) rather than the symmetrical one (CPTU) is solely formed in the vulcanizates under discussion. The accelerating as well as retarding effect of thiourea has been reported by Dućhac^ek in the vulcanization of NR. Substituted thiourea, namely, bis(oxydiethylene) thiourea, has also been shown to influence the vulcanization of SBR in the presence of a mixture of accelerators formed by the early reaction of OTOS and OBTS. The influence of PMTU, however, remains to be investigated, and studies in this line are being pursued. Also, we could not isolate the effect of MDB from that of CPTD, since both of them have the same retention time. From our experience, we know that in comparison with CPTD, the proportion of MDB formed under the experimental conditions is very low and, hence, it is believed that CPTD plays the major role. It has also been observed that BPTD rapidly transforms into BPTM which, as noticed by us, also influences vulcanization. It is concluded that in the binary system containing CTOS and MBTS, the intermediate accelerators, OBTS, CPTD, and BPTD play a vital role, and their growth and decay, either in the presence or absence of the ZDC, control the fate of the vulcanization reaction.

scholarly journals Fertilizers, BT technology, and insecticides contributed to 60%, 23%, and 17%, respectively to the increase in BT cotton yield: An analysis from 2000 to 2014 in India

2020 ◽  
Author(s):  
C Parameswaran ◽  
B Cayalvizhi
Keyword(s):  
Crop Improvement ◽  
Research Priorities ◽  
Agricultural Practices ◽  
Economic Benefits ◽  
High Yield ◽  
Optimum Dose ◽  
Bt Cotton ◽  
Individual Effect ◽  
Cotton Yield ◽  
The Individual

AbstractComplementary technologies and agricultural practices capable of sustaining profitability to the farmers cultivating BtCotton in India require urgent attention. In India, approval of Btcotton, cultivation of fertilizer-intensive hybrids, higher dose of fertilizer application by farmers, usage of novel pesticides all happened simultaneously during the same period (2002-04) which makes very difficult to identify the individual effect in the yield gain of cotton. In this background, we attempted to understand the proportionate contribution of fertilizers, BT technology and novel group of pesticides in enhancing cotton yield in India. For the analysis, linear regression model and change in partial factor productivity (PFP) of cotton was considered in four different scenarios for yield estimation between 2000 and 2014, i.e. Scenario I: Cotton yield in the absence of technology and enhanced fertilizers usage, Scenario II: Cotton yield only due to enhanced fertilizer usage, Scenario III: Cotton yield with enhanced fertilizer and application of novel pesticides for the insect control, and Scenario IV: Cotton yield due to BT technology, enhanced use of fertilizer, and novel insecticides (actual yield of Cotton in India during Bt phase).Their comparison showed that the individual effect of fertilizers, BT technology and insecticides contributed to 60%, 23% and 17% of cotton yield, respectively in India. Further, 18% reduction in PFP was observed recently as compared to 2003-08. Besides, 125 Kg/ha of fertilizers was identified as optimum dose for sustaining high yield in cotton. Thus, present analysis identified the individual effect of different technologies contributing to the yield of cotton in India which can be used in decision making processes for crop improvement. Further, in our opinion, three strategies namely drip fertigation, intercrossing Bt and non-Bt hybrids for resistance management in bollworms, and IPM for sucking pests will primarily drive the research priorities and policy actions for the next 5 to 10 years in sustaining the economic benefits of the six million cotton farmers in India.

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