scholarly journals Cloning, Expression and Characterization of an Esterase Gene in a Metagenomic Library of Traditional Fermented Food

2018 ◽  
Vol 22 (2) ◽  
pp. 33-41
Author(s):  
Mao Ye ◽  
Maocheng Deng
Keyword(s):  
Catalytic Activity ◽  
Recombinant Expression ◽  
Metagenomic Library ◽  
Carbon Chain ◽  
Fermented Food ◽  
High Catalytic Activity ◽  
New Class ◽  
Novel Esterase ◽  
Esterase Gene ◽  
Traditional Fermented Food

Abstract Esterase is an industrial enzyme that is widely used in food, medicine, fine chemicals. The total genomic DNA was extracted from traditional fermented food in China to construct a metagenomic library that included a novel esterase gene (est_115). Sequence homology analysis showed that the highest homology with the carboxylester hydrolase from Pseudomonas lutea was 38%, indicating that esterase belongs to a new class of esterases. Then, an est_115 gene recombinant expression vector was constructed and expressed. The Est_115 had higher catalytic activity to p-nitrophenol ester, with a short acyl-carbon chain. The enzyme can maintain high catalytic activity and salt tolerance in 10%–18% NaCl, suggesting that this novel esterase can be used in processing food using high osmotic pressure.

Conductive MOFs as bifunctional oxygen electrocatalysts for all-solid-state Zn–air batteries

2020 ◽  
Vol 56 (88) ◽  
pp. 13615-13618 ◽  
Author(s):  
Na Pan ◽  
Hanwen Zhang ◽  
Bo Yang ◽  
Hui Qiu ◽  
Longyan Li ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Solid State ◽  
High Catalytic Activity ◽  
Bifunctional Electrocatalyst ◽  
New Class

A new class of conductive MOFs can be directly used as a bifunctional electrocatalyst for both the ORR and OER. By adding Ru into the pristine MOF, the resultant catalyst exhibits high catalytic activity in all-solid-state Zn–air batteries.

scholarly journals A novel esterase gene cloned from a metagenomic library from neritic sediments of the South China Sea

2011 ◽  
Vol 10 (1) ◽  
pp. 95 ◽  
Author(s):  
Qing Peng ◽  
Xue Zhang ◽  
Meng Shang ◽  
Xu Wang ◽  
Guili Wang ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Metagenomic Library ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Novel Esterase ◽  
Esterase Gene

Molecule-level graphdiyne coordinated transition metals as a new class of bifunctional electrocatalysts for oxygen reduction and oxygen evolution reactions

2019 ◽  
Vol 21 (35) ◽  
pp. 19651-19659 ◽  
Author(s):  
Zhen Feng ◽  
Renyi Li ◽  
Yaqiang Ma ◽  
Yi Li ◽  
Dong Wei ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Transition Metals ◽  
Oxygen Reduction ◽  
Oxygen Evolution ◽  
Single Atom ◽  
High Catalytic Activity ◽  
New Class ◽  
Bifunctional Electrocatalysts

Graphdiyne (GDY) could provide a unique platform for synthesizing uniform single-atom catalysts (SACs) with high catalytic activity toward oxygen reduction (ORR) and oxygen evolution (OER) reactions.

scholarly journals A novel esterase from a soil metagenomic library displaying a broad substrate range

AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jian Yao ◽  
Lun Gui ◽  
Shaocheng Yin
Keyword(s):  
Metagenomic Library ◽  
Feruloyl Esterase ◽  
Structural Motif ◽  
Soluble Form ◽  
Sds Page ◽  
Phenolic Esters ◽  
Acyl Chains ◽  
Novel Esterase ◽  
Esterase Gene ◽  
Ph Range

AbstractA novel esterase gene was isolated from a soil metagenomic library. The gene encoded a protein of 520 amino acids which contained a 21 aa signal peptide. Primary structure analysis of the protein sequence revealed that it contained a conserved active site motif (SxSxG) and a structural motif (CS-D-HC). Then the esterase gene was cloned and expressed in Escherichia coli BL21(DE3). SDS-PAGE analysis of the purified esterase showed that it was expressed in a highly soluble form and its molecular mass was estimated to be 55 kDa. Characterization of the esterase revealed that it exhibited high activity toward p-nitrophenyl esters with short acyl chains and especially p-nitrophenyl acetate, suggesting that it was a typical carboxylesterase rather than a lipase. With p-nitrophenyl acetate as substrate, the enzyme showed its optimal activity at pH 7.0 and 30 °C, and it was stable at a broad pH range from 4.5 to 10.0 and temperature not higher than 50 °C. Furthermore, the enzyme showed different substrate specificity from known esterase, it was not only hydrolyzing against p-nitrophenyl esters, but also hydrolyzing all hydroxybenzoic esters and hydroxycinnamic ester assayed. As it was an enzyme active on a broad range of phenolic esters, simultaneously possessing feruloyl esterase, chlorogenate esterase and tannase activities, it could serve as a valuable candidate for applications in biotechnology.

Enhanced catalytic activity of low-Pt content nanocatalysts supported on hollow carbon spheres for the ORR in alkaline media

MRS Advances ◽  
2020 ◽  
Vol 5 (57-58) ◽  
pp. 2961-2972
Author(s):  
P.C. Meléndez-González ◽  
E. Garza-Duran ◽  
J.C. Martínez-Loyola ◽  
P. Quintana-Owen ◽  
I.L. Alonso-Lemus ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Anion Exchange ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Alkaline Media ◽  
High Catalytic Activity ◽  
Average Particle ◽  
Carbon Spheres ◽  
Hollow Carbon ◽  
Hollow Carbon Spheres

In this work, low-Pt content nanocatalysts (≈ 5 wt. %) supported on Hollow Carbon Spheres (HCS) were synthesized by two routes: i) colloidal conventional polyol, and ii) surfactant-free Bromide Anion Exchange (BAE). The nanocatalysts were labelled as Pt/HCS-P and Pt/HCS-B for polyol and BAE, respectively. The physicochemical characterization of the nanocatalysts showed that by following both methods, a good control of chemical composition was achieved, obtaining in addition well dispersed nanoparticles of less than 3 nm TEM average particle size (d) on the HCS. Pt/HCS-B contained more Pt0 species than Pt/HCS-P, an effect of the synthesis method. In addition, the structure of the HCS remains more ordered after BAE synthesis, compared to polyol. Regarding the catalytic activity for the Oxygen Reduction Reaction (ORR) in 0.5 M KOH, Pt/HCS-P and Pt/HCS-B showed a similar performance in terms of current density (j) at 0.9 V vs. RHE than the benchmark commercial 20 wt. % Pt/C. However, Pt/HCS-P and Pt/HCS-B demonstrated a 6 and 5-fold increase in mass catalytic activity compared to Pt/C, respectively. A positive effect of the high specific surface area of the HCS and its interactions with metal nanoparticles and electrolyte, which promoted the mass transfer, increased the performance of Pt/HCS-P and Pt/HCS-B. The high catalytic activity showed by Pt/HCS-B and Pt/HCS-P for the ORR, even with a low-Pt content, make them promising cathode nanocatalysts for Anion Exchange Membrane Fuel Cells (AEMFC).

Ordered Intermetallic Nanoparticles with High Catalytic Activity Prepared by an Electrochemically Induced Phase Transformation

2019 ◽  
Author(s):  
Du Sun ◽  
yunfei wang ◽  
Kenneth Livi ◽  
chuhong wang ◽  
ruichun luo ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Diffusion Mechanism ◽  
Reduction Reaction ◽  
Atomic Scale ◽  
High Catalytic Activity ◽  
Ambient Conditions ◽  
Magnetic Devices ◽  
Disordered Alloys ◽  
Ordered Intermetallic ◽  
Intermetallic Nanoparticles

<div> <p>The synthesis of alloys with long range atomic scale ordering (ordered intermetallics) is an emerging field of nanochemistry. Ordered intermetallic nanoparticles are useful for a wide variety of applications such as catalysis, superconductors, and magnetic devices. However, the preparation of nanostructured ordered intermetallics is challenging in comparison to disordered alloys, hindering progress in materials development. We report a process for converting colloidally synthesized ordered intermetallic PdBi<sub>2</sub> to ordered intermetallic Pd<sub>3</sub>Bi nanoparticles under ambient conditions by an electrochemically induced phase transition. The low melting point of PdBi<sub>2</sub> corresponds to low vacancy formation energies which enables the facile removal of the Bi from the surface, while simultaneously enabling interdiffusion of the constituent atoms via a vacancy diffusion mechanism under ambient conditions. The resulting phase-converted ordered intermetallic Pd<sub>3</sub>Bi exhibits 11x and 3.5x higher mass activty and high methanol tolerance for the oxygen reduction reaction compared to Pt/C and Pd/C, respectively,which is the highest reported for a Pd-based catalyst, to the best of our knowledge. These results establish a key development in the synthesis of noble metal rich ordered intermetallic phases with high catalytic activity, and sets forth guidelines for the design of ordered intermetallic compounds under ambient conditions.</p> </div>

Nickel (II) and oxovanadium (IV) complexes supported on MCM-41 mesoporous and their application in catalytic selective sulfide and thiol oxidation

2020 ◽  
Vol 23 ◽  
Author(s):  
Mohsen Nikoorazm ◽  
Maryam Khanmoradi ◽  
Masoumeh Sayadian
Keyword(s):  
Catalytic Activity ◽  
Room Temperature ◽  
Sol Gel ◽  
Reaction Times ◽  
Significant Loss ◽  
Spectral Studies ◽  
High Catalytic Activity ◽  
Catalytic Systems ◽  
Solvent Free Conditions ◽  
Mcm 41

Introduction:: MCM-41 was synthesized using the sol-gel method. Then two new transition metal complexes of Nickel (II) and Vanadium (IV), were synthesized by immobilization of adenine (6-aminopurine) into MCM-41 mesoporous. The compounds have been characterized by XRD, TGA, SEM, AAS and FT-IR spectral studies. Using these catalysts provided an efficient and enantioselective procedure for oxidation of sulfides to sulfoxides and oxidative coupling of thiols to their corresponding disulfides using hydrogen peroxide at room temperature. Materials and Methods:: To a solution of sulfide or thiol (1 mmol) and H2O2 (5 mmol), a determined amount of the catalyst was added. The reaction mixture was stirred at room temperature for the specific time under solvent free conditions. The progress of the reaction was monitored by TLC using n-hexane: acetone (8:2). Afterwards, the catalyst was removed from the reaction mixture by centrifugation and, then, washed with dichloromethane in order to give the pure products. Results:: All the products were obtained in excellent yields and short reaction times indicating the high activity of the synthesized catalysts. Besides, the catalysts can be recovered and reused for several runs without significant loss in their catalytic activity. Conclusion:: These catalytic systems furnish the products very quickly with excellent yields and VO-6AP-MCM-41 shows high catalytic activity compared to Ni-6AP-MCM-41.

High Throughput Biotechnology in Traditional Fermented Food Industry

2010 ◽  
Vol 2 (3) ◽  
pp. 251-257 ◽  
Author(s):  
Yong Yang ◽  
Rong-man Xu ◽  
Jia Song ◽  
Wei-min Wang
Keyword(s):  
High Throughput ◽  
Food Industry ◽  
Fermented Food ◽  
Traditional Fermented Food

High Throughput Biotechnology in Traditional Fermented Food Industry

2010 ◽  
Vol 2 (3) ◽  
pp. 251-257
Author(s):  
Yong Yang ◽  
Rong-man Xu ◽  
Jia Song ◽  
Wei-min Wang
Keyword(s):  
High Throughput ◽  
Food Industry ◽  
Fermented Food ◽  
Traditional Fermented Food
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