scholarly journals Thermostable manganese (II) dependent α-glycosidase from Pseudothermotoga thermarum

BioResources ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. 7266-7274
Author(s):  
Hao Shi ◽  
Yue Liu ◽  
Jiannan Guo ◽  
Yang Cao ◽  
Xianyan Zhu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Gel Filtration ◽  
Recombinant Enzyme ◽  
Relative Molecular Mass ◽  
Optimal Temperature ◽  
Good Thermal Stability ◽  
E Coli ◽  
Purification System ◽  
Optimal Ph

Alpha-glycosidase degrades polysaccharides and oligosaccharides and participates in the synthesis of oligosaccharides through a process called transglycosylation. In this study, an α-glycosidase gene pthgly from Pseudothermotoga thermarum was cloned using pET-20b as a vector and was expressed in E. coli BL21(DE3). After heat treatment and affinity chromatography, the resulting recombinant enzyme was purified. The purity of the enzyme reached a single band at a molecular weight of approximately 55 kDa. The properties of the recombinant enzyme were determined. The optimal temperature of α-glycosidase (Pthgly) was 90 °C and the optimal pH was 7.5. In addition, Pthgly exhibited good thermal stability at 70 °C and 75 °C. The relative molecular mass of the recombinant enzyme was 116 kDa, as determined by a protein purification system with a gel filtration column. Furthermore, α-glycosidase possessed Michaelis-Menten kinetics with a Km and Vmax of 0.29 ± 0.01 mmol l-1 and 22.12 ± 1.31 μmol min-1 mg-1, respectively.

Effect of Heat Treatment on Mechanical Properties of ECAPed 7075 Aluminum Alloy

2013 ◽  
Vol 829 ◽  
pp. 62-66 ◽  
Author(s):  
Alireza Fallahi ◽  
Hossein Hosseini-Toudeshky ◽  
Seyed Mahmoud Ghalehbandi
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Thermal Stability ◽  
Aluminum Alloy ◽  
Solution Treatment ◽  
7075 Aluminum Alloy ◽  
Ecap Processing ◽  
Good Thermal Stability ◽  
7075 Alloy

It is the objective of this study to investigate the effect of ECAP processing and heat treatment on the mechanical properties of the UFG 7075 alloy. Also the effect of post ECAP heat treatment is investigated. The alloy is processed by ECAP after annealing as well as solution treatment to produce an UFG structure. Furthermore mechanical properties and their variations during annealing and aging are investigated. The hardness of the pre-ECAP annealed and the pre-ECAP solutionised 7075 aluminum alloy has increased significantly compared with that of the CG sample. Also hardness of ECAPed specimen has not experienced significant changes in post-ECAP heat treatment and indicated that the alloy had approximately good thermal stability.

scholarly journals Efficient Synthesis of PVDF/PI Side-by-Side Bicomponent Nanofiber Membrane with Enhanced Mechanical Strength and Good Thermal Stability

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 39 ◽  
Author(s):  
Ming Cai ◽  
Hongwei He ◽  
Xiao Zhang ◽  
Xu Yan ◽  
Jianxin Li ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Mechanical Strength ◽  
Polyvinylidene Fluoride ◽  
Chemical Structure ◽  
Electrospun Fiber ◽  
Nanofiber Membrane ◽  
Application Range ◽  
Good Thermal Stability ◽  
Filtration Properties

Bicomponent composite fibers, due to their unique versatility, have attracted great attention in many fields, such as filtration, energy, and bioengineering. Herein, we efficiently fabricated polyvinylidene fluoride/polyimide (PVDF/PI) side-by-side bicomponent nanofibers based on electrospinning, which resulted in the synergism between PVDF and PI, and eventually obtained the effect of 1 + 1 > 2. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the morphology and chemical structure of nanofibers, indicating that a large number of side-by-side nanofibers were successfully prepared. Further, the thermal stability, mechanical strength, and filtration properties of PVDF/PI were carefully investigated. The results revealed that the bicomponent nanofibers possessed both good mechanical strength and remarkable thermal stability. Moreover, the mechanical properties of PVDF/ PI were strengthened by more than twice after the heat treatment (7.28 MPa at 25 °C, 15.49 MPa at 230 °C). Simultaneously, after the heat treatment at 230 °C for 30 min, the filtration efficiency of PVDF/PI membrane was maintained at about 95.45 ± 1.09%, and the pressure drop was relatively low. Therefore, the prepared PVDF/PI side-by-side bicomponent nanofibers have a favorable prospect of application in the field of medium- and high-temperature filtration, which further expands the application range of electrospun fiber membranes.

Construction of a Novel Recombinant Escherichia coli Strain Capable of Producing 1,3–propanediol

2011 ◽  
Vol 396-398 ◽  
pp. 2499-2502 ◽  
Author(s):  
Xiang Hui Qi ◽  
Qi Guo ◽  
Yu Tuo Wei ◽  
Hong Xu ◽  
Ri Bo Huang
Keyword(s):  
Escherichia Coli ◽  
Specific Activity ◽  
Gel Filtration ◽  
Coli Strain ◽  
Optimal Temperature ◽  
Recombinant Enzymes ◽  
Microbial Conversion ◽  
Gene Encoding ◽  
E Coli ◽  
Nickel Chelate

1, 3-propanediol (1, 3-PD) is biologically synthesized by glycerol dehydratase (GDHt) and 1, 3-propanediol dehydrogenase (PDOR). In present study, the gldABC gene, encoding GDHt from Klebsiella pneumoniae and the yqhD gene, encoding PDOR isoenzyme from E.coli BL21 were cloned and co-expressed in E.coli JM109 using plasmid pSE380. The over-expressed recombinant enzymes were purified by nickel-chelate chromatography combined with gel filtration to study the properties. Optimal temperature and pH of recombinant GDHt with specific activity of 85.8 U/mg were 45 °C and 9.0; and optimal temperature and pH of recombinant YqhD with specific activity of 80.0 U/mg were 37 °C, 7.0. The microbial conversion of 1,3-PD from glycerol by this recombinant E. coli strain was studied and the production of 1,3-PD was about 28.0 g/l.

scholarly journals Study of ALDH from Thermus thermophilus–Expression, Purification and Characterisation of the Non-Substrate Specific, Thermophilic Enzyme Displaying Both Dehydrogenase and Esterase Activity

Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3535
Author(s):  
Kim Shortall ◽  
Edel Durack ◽  
Edmond Magner ◽  
Tewfik Soulimane
Keyword(s):  
Heat Treatment ◽  
Life Form ◽  
Thermus Thermophilus ◽  
Gel Filtration ◽  
Aldehyde Dehydrogenases ◽  
E Coli ◽  
Ability To Act ◽  
High Yields ◽  
Treatment Step ◽  
Heat Treatment Step

Aldehyde dehydrogenases (ALDH), found in all kingdoms of life, form a superfamily of enzymes that primarily catalyse the oxidation of aldehydes to form carboxylic acid products, while utilising the cofactor NAD(P)+. Some superfamily members can also act as esterases using p-nitrophenyl esters as substrates. The ALDHTt from Thermus thermophilus was recombinantly expressed in E. coli and purified to obtain high yields (approximately 15–20 mg/L) and purity utilising an efficient heat treatment step coupled with IMAC and gel filtration chromatography. The use of the heat treatment step proved critical, in its absence decreased yield of 40% was observed. Characterisation of the thermophilic ALDHTt led to optimum enzymatic working conditions of 50 °C, and a pH of 8. ALDHTt possesses dual enzymatic activity, with the ability to act as a dehydrogenase and an esterase. ALDHTt possesses broad substrate specificity, displaying activity for a range of aldehydes, most notably hexanal and the synthetic dialdehyde, terephthalaldehyde. Interestingly, para-substituted benzaldehydes could be processed efficiently, but ortho-substitution resulted in no catalytic activity. Similarly, ALDHTt displayed activity for two different esterase substrates, p-nitrophenyl acetate and p-nitrophenyl butyrate, but with activities of 22.9 and 8.9%, respectively, compared to the activity towards hexanal.

Evaluation of juice purification in sugar factories

2014 ◽  
pp. 734-744
Author(s):  
Mohsen Ajdari Rad ◽  
Gilles Schrevel
Keyword(s):  
Sugar Beet ◽  
Chemical Reactions ◽  
Retention Time ◽  
Ph Value ◽  
Substantial Improvement ◽  
Optimal Temperature ◽  
The Past ◽  
Purification System ◽  
Physical And Chemical ◽  
Optimal Ph

Despite the substantial improvement of beet quality which has been achieved, still a relatively high content of nonsugars remains in the raw juice extracted from sugar beet. New analytical methods and instrumentation have helped to better understand the various physical and chemical reactions taking place during the different steps of juice purification and so how they can be affected. Some examples of developments over the past 20 years by the R&D departments of the Südzucker Group, related to the optimization of the juice purification system, are illustrated: raw juice viscosimetry, raw juice pre-alkalization, optimal pH value of flocculation in the prelimer, optimal course of pH value in the prelimer, optimal temperature/retention time in the prelimer and main limer, optimal pH value of 1st carbonatation, milk of lime optimization system (LIMOS) to reduce limestone consumption, lime salts analyzer (LISA), optimization of decalcification, SZ/RT-juice purification system with separation of the colloid fraction after the prelimer.

scholarly journals Evaluation of the Heat Inactivation of Escherichia coli and Lactobacillus plantarum by Differential Scanning Calorimetry

2002 ◽  
Vol 68 (11) ◽  
pp. 5379-5386 ◽  
Author(s):  
Jaesung Lee ◽  
Gönül Kaletunç
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Lactobacillus Plantarum ◽  
Plate Count ◽  
Scanning Calorimetry ◽  
Whole Cells ◽  
E Coli ◽  
Thermal Stability Of

ABSTRACT Differential scanning calorimetry (DSC) is used to evaluate the thermal stability and reversibility after heat treatment of transitions associated with various cellular components of Escherichia coli and Lactobacillus plantarum. The reversibility and the change in the thermal stability of individual transitions are evaluated by a second temperature scan after preheating in the DSC to various temperatures between 40 and 130°C. The viability of bacteria after a heat treatment between 55 and 70°C in the DSC is determined by both plate count and calorimetric data. The fractional viability values based on calorimetric and plate count data show a linear relationship. Viability loss and the irreversible change in DSC thermograms of pretreated whole cells are highly correlated between 55 and 70°C. Comparison of DSC scans for isolated ribosomes shows that the thermal stability of E. coli ribosomes is greater than that of L. plantarum ribosomes, consistent with the greater thermal tolerance of E. coli observed from viability loss and DSC scans of whole cells.

TEXTURE AND STRUCTURE VARIATION OF PEROVSKITE LaFeO3/ZSM-5 DURING HIGH-TEMPERATURE DESULFURIZATION

2019 ◽  
Vol 27 (05) ◽  
pp. 1950151
Author(s):  
DONGJING LIU ◽  
WEIGUO ZHOU ◽  
JIANG WU
Keyword(s):  
Heat Treatment ◽  
Activation Energy ◽  
Thermal Stability ◽  
High Temperature ◽  
High Temperatures ◽  
Textural Property ◽  
Structure Variation ◽  
Good Thermal Stability ◽  
Sulfur Capacity

Perovskite LaFeO3/ZSM-5 is synthesized via citrate route for H2S removal at high temperatures. It shows good thermal stability after heat treatment at 500–700∘C with respect to slight changes in crystallographic phase and textural property. It presents the optimal desulfurization performance at 600∘C with sulfur capacity of 1017[Formula: see text][Formula: see text]mol[Formula: see text]S/g and products of S, LaS2, and Fe7S8. Sulfidation at 500∘C yields the same products as sulfidation at 600∘C but displays the lowest sulfur capacity of 408[Formula: see text][Formula: see text]mol[Formula: see text]S/g. Sulfidation at 700∘C produces La2O2S, Fe3S4, and unreacted LaFeO3. The activation energy of the sulfidation reaction over LaFeO3/ZSM-5 is 109.6[Formula: see text]kJ/mol.

Production and purification of an extracellular β-galactosidase from the Dutch elm disease fungus Ophiostoma novo-ulmi

1997 ◽  
Vol 43 (11) ◽  
pp. 1011-1016 ◽  
Author(s):  
Thomas Binz ◽  
Colette Gremaud ◽  
Giorgio Canevascini
Keyword(s):  
Enzyme Activity ◽  
Culture Filtrate ◽  
Galacturonic Acid ◽  
Gel Filtration ◽  
Total Activity ◽  
Dutch Elm Disease ◽  
Optimal Temperature ◽  
Ophiostoma Ulmi ◽  
Sds Page ◽  
Optimal Ph

The causal agents of Dutch elm disease, Ophiostoma ulmi (isolate H200) and Ophiostoma novo-ulmi (isolate CKT-11), secreted similar amounts of β-galactosidase in liquid shake cultures when grown on galacturonic acid or sodium pectate (1.45 ± 0.16 and 1.03 ± 0.24 nkat∙mL−1 for O. ulmi, respectively, and 1.30 ± 0.08 and 1.28 ± 0.26 nkat∙mL−1 for O. novo-ulmi, respectively). Rhamnose and pectin also stimulated secretion but to a lesser extent, whereas on glucose, enzyme activity was barely detectable (≤0.01 nkat∙mL−1). Ophiostoma novo-ulmi was shown by Q-Sepharose chromatography to form two β-galactosidases, named β-galactosidases I and II. In cultures grown on galacturonic acid β-galactosidase I accounted for approximately 75% of the total activity in the culture filtrate. β-Galactosidase I was further purified to apparent electrophoretic homogeneity by means of Sephacryl gel filtration chromatography, chromatofocusing, and Superdex75 gel filtration. The molecular mass of the enzyme was 135 kDa by SDS–PAGE and 123 kDa by gel filtration. Its isoelectric point, determined by chromatofocusing, was 4.9. The optimal pH for enzyme activity was 5.8 and the optimal temperature was 50 °C. The Km values for p-nitrophenyl β-D-galactopyranoside and lactose were 7.52 and 14.23 mM, respectively, and the maximum velocities for these substrates were 1733 and 355 nkat∙mg protein−1, respectively. The Ki value for D(−)-galactonic acid γ-lactone was 2.29 mM.Key words: Dutch elm disease, β-galactosidase, Ophiostoma ulmi, Ophiostoma novo-ulmi.

Thermal Stability and Mechanical Properties of Plasma Sprayed Al2O3/ZrO2 Nano-Composite Coating

2006 ◽  
Vol 317-318 ◽  
pp. 513-516 ◽  
Author(s):  
Satoshi Sodeoka ◽  
Masato Suzuki ◽  
Takahiro Inoue
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Thermal Stability ◽  
Composite Coating ◽  
Grain Growth ◽  
Nano Composite ◽  
Good Thermal Stability ◽  
Fine Powders ◽  
Nano Composite Coating ◽  
Plasma Sprayed

Alumina/zirconia nano-composite coating was fabricated by plasma spraying using agglomerated feedstock from fine powders of about 100 nm. The coating was consisted of fine γ-alumina and zirconia crystals with size of several nano meter and some amorphous boundary layers. The amorphous phase was crystallized and disappeared after heat treatment at 930°C. However, the crystallite size was kept under 50 nm even after 1500°C-100hr heating, so the alumina-zirconia nano-composite showed good thermal stability against the grain growth.

Amylase Immobilized on a Reticulated Polymer Containing Rosin Group

2011 ◽  
Vol 361-363 ◽  
pp. 1432-1436
Author(s):  
Qian Zeng ◽  
Hao Ma ◽  
Fu Hou Lei ◽  
Hong Quan Liu ◽  
Cui Hong Tang
Keyword(s):  
Thermal Stability ◽  
Amylase Activity ◽  
Optimal Temperature ◽  
Acid Base ◽  
Polymer Carriers ◽  
Base Stability ◽  
Optimal Ph

Two polymer carriers of reticulated rosin group were synthesized to immobilize amylase in this paper, the nature of immobilized amylase was inspected. Results indicated that the optimal temperature for immobilize amylase was 40 °C, the optimal pH was 6.4, thermal stability and acid-base stability was superior to free amylase, 17% of the amylase activity existed after been used six times.

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