scholarly journals Rational Design of Alginate Lyase from Microbulbifer sp. Q7 to Improve Thermal Stability

Marine Drugs ◽  
2019 ◽  
Vol 17 (6) ◽  
pp. 378 ◽  
Author(s):  
Min Yang ◽  
Su-Xiao Yang ◽  
Zhe-Min Liu ◽  
Nan-Nan Li ◽  
Li Li ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Disulfide Bonds ◽  
Rational Design ◽  
Spatial Configuration ◽  
Specific Activity ◽  
Alginate Lyase ◽  
Life Time ◽  
Enzyme Specific Activity ◽  
Elimination Mechanism ◽  
Thermal Stability Of

Alginate lyase degrades alginate by the β-elimination mechanism to produce oligosaccharides with special bioactivities. The low thermal stability of alginate lyase limits its industrial application. In this study, introducing the disulfide bonds while using the rational design methodology enhanced the thermal stability of alginate lyase cAlyM from Microbulbifer sp. Q7. Enzyme catalytic sites, secondary structure, spatial configuration, and molecular dynamic simulation were comprehensively analyzed. When compared with cAlyM, the mutants D102C-A300C and G103C-T113C showed an increase by 2.25 and 1.16 h, respectively, in half-life time at 45 °C, in addition to increases by 1.7 °C and 0.4 °C in the melting temperature, respectively. The enzyme-specific activity and kcat/Km values of D102C-A300C were 1.8- and 1.5-times higher than those of cAlyM, respectively. The rational design strategy that was used in this study provides a valuable method for improving the thermal stability of the alginate lyase.

scholarly journals Engineering Improves Enzymatic Synthesis of L-Tryptophan by Tryptophan Synthase from Escherichia coli

2020 ◽  
Vol 8 (4) ◽  
pp. 519
Author(s):  
Lisheng Xu ◽  
Fangkai Han ◽  
Zeng Dong ◽  
Zhaojun Wei
Keyword(s):  
Thermal Stability ◽  
Amino Acid ◽  
Directed Evolution ◽  
Amino Acid Residue ◽  
Rational Design ◽  
Molecular Engineering ◽  
Mutant Enzyme ◽  
Tryptophan Synthase ◽  
Mutant Library ◽  
Thermal Stability Of

To improve the thermostability of tryptophan synthase, the molecular modification of tryptophan synthase was carried out by rational molecular engineering. First, B-FITTER software was used to analyze the temperature factor (B-factor) of each amino acid residue in the crystal structure of tryptophan synthase. A key amino acid residue, G395, which adversely affected the thermal stability of the enzyme, was identified, and then, a mutant library was constructed by site-specific saturation mutation. A mutant (G395S) enzyme with significantly improved thermal stability was screened from the saturated mutant library. Error-prone PCR was used to conduct a directed evolution of the mutant enzyme (G395S). Compared with the parent, the mutant enzyme (G395S /A191T) had a Km of 0.21 mM and a catalytic efficiency kcat/Km of 5.38 mM−1∙s−1, which was 4.8 times higher than that of the wild-type strain. The conditions for L-tryptophan synthesis by the mutated enzyme were a L-serine concentration of 50 mmol/L, a reaction temperature of 40 °C, pH of 8, a reaction time of 12 h, and an L-tryptophan yield of 81%. The thermal stability of the enzyme can be improved by using an appropriate rational design strategy to modify the correct site. The catalytic activity of tryptophan synthase was increased by directed evolution.

scholarly journals Thermal decomposition kinetic study of multiwalled carbon nanotube buckypaper-reinforced poly(ether-imide) composites

2017 ◽  
Vol 32 (1) ◽  
pp. 62-75 ◽  
Author(s):  
Bruno Ribeiro ◽  
LFP Santos ◽  
AL Santos ◽  
ML Costa ◽  
EC Botelho
Keyword(s):  
Thermal Stability ◽  
Carbon Nanotube ◽  
Life Time ◽  
Strong Increase ◽  
Multiwalled Carbon ◽  
Vacuum Filtration ◽  
Degradation Temperature ◽  
Triton X ◽  
Thermal Stability Of ◽  
Filtration Technique

Poly(ether-imide) (PEI)-based composites filled with multiwalled carbon nanotubes in a dispersed form (1.0 wt%) and as buckypaper (BP) (25 wt%) have been prepared by mixing solution and hot compression molding technique, respectively. Vacuum filtration technique with the aid of water-based surfactant Triton X-100 was employed to produce BP sheets. The thermal stability of the composites was evaluated by thermogravimetric analysis and revealed a strong increase in thermal degradation temperature when BPs were used as nanofiller. Ozawa–Wall–Flyn model was used to determine the kinetic parameters. It was observed an increase in activation energy as the nanotubes concentration rise, suggesting the formation of more thermally stable systems. In addition, half-life time as function of temperature demonstrated that BP-based composites could operate for 3200 years at 200°C. These results concluded that carbon nanotube BP could contribute to improve significantly the thermal stability of PEI matrix.

scholarly journals Certification of a New Batch of the Industry Reference Standard for the Control of Specific Activity and Thermal Stability of Live Plague Vaccine

2018 ◽  
Vol 18 (4) ◽  
pp. 262-267 ◽  
Author(s):  
I. V. Kasina ◽  
S. A. Alekseeva ◽  
O. V. Fadeykina ◽  
T. I. Nemirovskaya ◽  
R. A. Volkova
Keyword(s):  
Thermal Stability ◽  
Specific Activity ◽  
Quality Parameters ◽  
Microbial Cell ◽  
Average Weight ◽  
Statistical Interpretation ◽  
Test Results ◽  
Reference Standard ◽  
Plague Vaccine ◽  
Thermal Stability Of

In accordance with the State Pharmacopoeia (SPh) requirements for live plague vaccine, a reference standard has to be used when testing the specific activity and thermal stability of plague vaccine commercial batches in order to assess the consistency and acceptability of the test results. Since there is no international reference standard for plague vaccine, the certification of a new batch of the industry reference standard (IRS) of live plague vaccine in terms of the above-mentioned quality parameters is an urgent challenge. Therefore, a certification programme for the industry reference standard was developed that establishes the design and scope of testing required to obtain statistically significant results. A candidate IRS was represented by a commercial batch of the product meeting the specification requirements for live plague vaccine. The certification parameters were: «Specific activity: microbial cell concentration», «Specific activity: live microbial cell percentage» and «Thermal stability». The article presents the results of the certification of a new batch of the live plague vaccine IRS, detailed evaluation of the candidate IRS in terms of: «Average weight and uniformity of weight», «Loss on drying», and statistical interpretation of the test results. It also summarises the results of the product testing in terms of «Specific activity: immunogenicity». The results of application of the previous batch of the live plague vaccine IRS (OSO 42-28-392-2013) and the results of monitoring the stability of its certification parameters demonstrated that the IRS shelf life could be extended by 6 months relative to the established period (from 2 to 2.5 years). All the certified and additional characteristics are reflected in the official documents for the scientific/technological product — live plague vaccine IRS, OSO 42-28-392-2017: passport, labelling and patient information leaflet.

scholarly journals A Review of the Current Knowledge of Thermal Stability of Anthocyanins and Approaches to Their Stabilization to Heat

Antioxidants ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1337
Author(s):  
Simona Oancea
Keyword(s):  
Thermal Stability ◽  
Rational Design ◽  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Scientific Progress ◽  
Bioactive Molecules ◽  
Environmental Stability ◽  
Published Data ◽  
Thermal Stability Of ◽  
Anthocyanin Degradation

Anthocyanins are colored valuable biocompounds, of which extraction increases globally, although functional applications are restrained by their limited environmental stability. Temperature is a critical parameter of food industrial processing that impacts on the food matrix, particularly affecting heat-sensitive compounds such as anthocyanins. Due to the notable scientific progress in the field of thermal stability of anthocyanins, an analytical and synthetic integration of published data is required. This review focuses on the molecular mechanisms and the kinetic parameters of anthocyanin degradation during heating, both in extracts and real food matrices. Several kinetic models (Arrhenius, Eyring, Ball) of anthocyanin degradation were studied. Crude extracts deliver more thermally stable anthocyanins than purified ones. A different anthocyanin behavior pattern within real food products subjected to thermal processing has been observed due to interactions with some nutrients (proteins, polysaccharides). The most recent studies on the stabilization of anthocyanins by linkages to other molecules using classical and innovative methods are summarized. Ensuring appropriate thermal conditions for processing anthocyanin-rich food will allow a rational design for the future development of stable functional products, which retain these bioactive molecules and their functionalities to a great extent.

Evaluation of Thermal Stability of Organic Electro-Optic Device by Using Thermally Stimulated Current

2016 ◽  
Vol 16 (4) ◽  
pp. 3378-3382 ◽  
Author(s):  
Ryoma Ikemoto ◽  
Dai Taguchi ◽  
Takaaki Manaka ◽  
Mitsumasa Iwamoto ◽  
Toshiki Yamada ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Life Time ◽  
Side Chain ◽  
Dominant Contribution ◽  
Thermally Stimulated Current ◽  
Chain Polymer ◽  
Electro Optic ◽  
Thermal Stability Of ◽  
Host Polymer

Thermally stimulated current (TSC) measurement was employed to study the thermal stability of electro-optic (EO) polymers, i.e., guest/host polymer DR1/PMMA and side-chain polymer PMMA-co-DR1. Here the isothermal relaxation test showed that the relaxation time τ (85 °C) of side-chain polymer PMMA-co-DR1 is longer than that of guest/host polymer DR1/PMMA. TSC peaks appeared symmetrically in proportion to the poling electric field Ep, indicating that DR1 molecules make a dominant contribution to dipolar depolarization. Thermal sampling (TS) method showed that the activation energy of the DR1/PMMA is around 1 eV, while that of the PMMA-co-DR1 is distributed > 1 eV. Results suggested that side-chain polymer is preferable to the guest/host polymer in the thermal stability. TSC measurement is helpful as a conventional method for studying the life time of EO polymers in terms of dipolar motion.

scholarly journals A Rational Design of the Sintering-Resistant Au-CeO2 Nanoparticles Catalysts for CO Oxidation: The Influence of H2 Pretreatments

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1952 ◽  
Author(s):  
Yuqi Sun ◽  
Wei Liu ◽  
Miao Tian ◽  
Liguo Wang ◽  
Zhongpeng Wang
Keyword(s):  
Thermal Stability ◽  
Co Oxidation ◽  
Noble Metal ◽  
Rational Design ◽  
Co Adsorption ◽  
Precipitation Method ◽  
Au Nps ◽  
Metal Support Interaction ◽  
H2 Pretreatment ◽  
Thermal Stability Of

The redox pretreatment of samples is one of the crucial ways of altering the catalytic properties of the supported noble metal materials in many heterogeneous reactions. Here, H2-reducing pretreatment is reported to enhance the thermal stability of Au-CeO2 catalysts prepared by the deposition–precipitation method and calcination at 600 °C for CO oxidation. In order to understand the improved activity and thermal stability, a series of techniques were used to characterize the physico-chemical changes of the catalyst samples. H2 pretreatment may lead to: (i) a strong metal–support interaction (SMSI) between Au nanoparticles (NPs) and CeO2, evidenced by the particular coverage of Au NPs by CeO2, electronic interactions and CO adsorption changes. (ii) the production of surface bicarbonates which can accelerate CO oxidation. As a result, the H2 pretreatment makes the Au NPs more resistant to sintering at high temperature and enhances the CO oxidation activity. Furthermore, this reduction pretreatment strategy may provide a potential approach to enhance the thermal-stability of other supported noble metal catalysts.

scholarly journals Immobilization of Soybean Lipoxygenase on Nanoporous Rice Husk Silica by Adsorption: Retention of Enzyme Function and Catalytic Potential

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 291
Author(s):  
Putheary Ngin ◽  
Kyoungwon Cho ◽  
Oksoo Han
Keyword(s):  
Thermal Stability ◽  
Rice Husk ◽  
Thermal Inactivation ◽  
Specific Activity ◽  
Silica Particles ◽  
Soybean Lipoxygenase ◽  
Desorption Kinetics ◽  
Rice Husk Silica ◽  
Kinetics Of ◽  
Thermal Stability Of

Soybean lipoxygenase was immobilized on nanoporous rice husk silica particles by adsorption, and enzymatic parameters of the immobilized protein, including the efficiency of substrate binding and catalysis, kinetic and operational stability, and the kinetics of thermal inactivation, were investigated. The maximal adsorption efficiency of soybean lipoxygenase to the silica particles was 50%. The desorption kinetics of soybean lipoxygenase from the silica particles indicate that the silica-immobilized enzyme is more stable in an anionic buffer (sodium phosphate, pH 7.2) than in a cationic buffer (Tris-HCl, pH 7.2). The specific activity of immobilized lipoxygenase was 73% of the specific activity of soluble soybean lipoxygenase at a high concentration of substrate. The catalytic efficiency (kcat/Km) and the Michaelis–Menten constant (Km) of immobilized lipoxygenase were 21% and 49% of kcat/Km and Km of soluble soybean lipoxygenase, respectively, at a low concentration of substrate. The immobilized soybean lipoxygenase was relatively stable, as the enzyme specific activity was >90% of the initial activity after four assay cycles. The thermal stability of the immobilized lipoxygenase was higher than the thermal stability of soluble lipoxygenase, demonstrating 70% and 45% of its optimal specific activity, respectively, after incubation for 30 min at 45 °C. These results demonstrate that adsorption on nanoporous rice husk silica is a simple and rapid method for protein immobilization, and that adsorption may be a useful and facile method for the immobilization of many biologically important proteins of interest.

Significant improvement of thermal stability of glucose 1-dehydrogenase by introducing disulfide bonds at the tetramer interface

2013 ◽  
Vol 53 (6-7) ◽  
pp. 365-372 ◽  
Author(s):  
Haitao Ding ◽  
Fen Gao ◽  
Danfeng Liu ◽  
Zeli Li ◽  
Xiaohong Xu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Disulfide Bonds ◽  
Thermal Stability Of

scholarly journals Construction of Highly Stable Cytotoxic Nuclear-Directed Ribonucleases

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3273 ◽  
Author(s):  
David Roura Padrosa ◽  
Jessica Castro ◽  
Alejandro Romero-Casañas ◽  
Marc Ribó ◽  
Maria Vilanova ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Tumor Cells ◽  
Disulfide Bonds ◽  
Site Directed Mutagenesis ◽  
Proteinase K ◽  
Human Sera ◽  
Localization Signal ◽  
Cytotoxic Proteins ◽  
Thermal Stability Of

Ribonucleases are proteins whose use is promising in anticancer therapy. We have previously constructed different human pancreatic ribonuclease variants that are selectively cytotoxic for tumor cells by introducing a nuclear localization signal into their sequence. However, these modifications produced an important decrease in their stability compromising their behavior in vivo. Here, we show that we can significantly increase the thermal stability of these cytotoxic proteins by introducing additional disulfide bonds by site-directed mutagenesis. One of these variants increases its thermal stability by around 17 °C, without affecting its catalytic activity while maintaining the cytotoxic activity against tumor cells. We also show that the most stable variant is significantly more resistant to proteolysis when incubated with proteinase K or with human sera, suggesting that its half-live could be increased in vivo once administered.

Sign in / Sign up

Export Citation Format

Share Document