scholarly journals Synthesis of L-asparagine Catalyzed by a Novel Asparagine Synthase Coupled With an ATP Regeneration System

2021 ◽  
Vol 9 ◽  
Author(s):  
Wei Luo ◽  
Jinglong Xu ◽  
Huiying Chen ◽  
Huili Zhang ◽  
Peilong Yang ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Large Scale ◽  
Reaction System ◽  
Coupling Reaction ◽  
Sodium Hexametaphosphate ◽  
Class Iii ◽  
Regeneration System ◽  
Batch Mode ◽  
Whole Cells ◽  
Atp Regeneration

Compared with low-yield extraction from plants and environmentally unfriendly chemical synthesis, biocatalysis by asparagine synthetase (AS) for preparation of L-asparagine (L-Asn) has become a potential synthetic method. However, low enzyme activity of AS and high cost of ATP in this reaction restricts the large-scale preparation of L-Asn by biocatalysis. In this study, gene mining strategy was used to search for novel AS with high enzyme activity by expressing them in Escherichia coli BL21 (DE3) or Bacillus subtilis WB600. The obtained LsaAS-A was determined for its enzymatic properties and used for subsequent preparation of L-Asn. In order to reduce the use of ATP, a class III polyphosphate kinase 2 from Deinococcus ficus (DfiPPK2-Ⅲ) was cloned and expressed in E. coli BL21 (DE3), Rosetta (DE3) or RosettagamiB (DE3) for ATP regeneration. A coupling reaction system including whole cells expressing LsaAS-A and DfiPPK2-Ⅲ was constructed to prepare L-Asn from L-aspartic acid (L-Asp). Batch catalytic experiments showed that sodium hexametaphosphate (>60 mmol L−1) and L-Asp (>100 mmol L−1) could inhibit the synthesis of L-Asn. Under fed-batch mode, L-Asn yield reached 90.15% with twice feeding of sodium hexametaphosphate. A final concentration of 218.26 mmol L−1 L-Asn with a yield of 64.19% was obtained when L-Asp and sodium hexametaphosphate were fed simultaneously.

Microcomputers in Political Science

1983 ◽  
Vol 38 ◽  
pp. 1-9
Author(s):  
Herbert F. Weisberg
Keyword(s):  
Data Analysis ◽  
Political Science ◽  
Large Scale ◽  
Turnaround Time ◽  
General Purpose ◽  
Batch Mode ◽  
New Era ◽  
Large Scale Data ◽  
The Social ◽  
Frequency Counts

We are now entering a new era of computing in political science. The first era was marked by punched-card technology. Initially, the most sophisticated analyses possible were frequency counts and tables produced on a counter-sorter, a machine that specialized in chewing up data cards. By the early 1960s, batch processing on large mainframe computers became the predominant mode of data analysis, with turnaround time of up to a week. By the late 1960s, turnaround time was cut down to a matter of a few minutes and OSIRIS and then SPSS (and more recently SAS) were developed as general-purpose data analysis packages for the social sciences. Even today, use of these packages in batch mode remains one of the most efficient means of processing large-scale data analysis.

Optimized Large Scale Synthesis of Phosphorothioate Oligonucleotides on PS-PEG Supports

1997 ◽  
Vol 52 (1) ◽  
pp. 110-116
Author(s):  
Michael Gerster ◽  
Martin Maier ◽  
Nils Clausen ◽  
Jens Schewitz ◽  
Ernst Bayer
Keyword(s):  
Gel Electrophoresis ◽  
Continuous Flow ◽  
Large Scale ◽  
Electrospray Mass Spectrometry ◽  
Small Scale ◽  
Batch Mode ◽  
Crucial Step ◽  
Capillary Gel Electrophoresis ◽  
Phosphoramidite Chemistry ◽  
Large Scale Synthesis

Sulphurization is a crucial step during synthesis of phosphorothioate oligonucleotides. Insufficient reaction leads to inhomogeneous products with phosphodiester defects and subsequently to destabilization of the oligomers in biological media. To achieve a maximum extent of sulphur incorporation, various sulphurizing agents have been investigated. Solely, the use of Beaucage reagent provided satisfactory results on PS-PEG supports. Based on our investigations in small scale synthesis (1 μmol) with continuous-flow technique, upscaling to the 0.1-0.25 mmolar range has been achieved using a peptide synthesizer. The syntheses were performed in batch mode with standard phosphoramidite chemistry. Additionally, large scale synthesis of a phosphodiester oligonucleotide has been carried out on PS-PEG with optimized protocols and compared to small scale synthesis on different supports. Products were analysed by 31P NMR, capillary gel electrophoresis and electrospray mass spectrometry. An extent of sulphurization of 99% and coupling effiencies of more than 99% were obtained and the products proved to have similar purity compared to small scale syntheses on CPG

scholarly journals Coupled structural transitions enable highly cooperative regulation of human CTPS2 filaments

2019 ◽  
Author(s):  
Eric M. Lynch ◽  
Justin M. Kollman
Keyword(s):  
Enzyme Activity ◽  
Active Sites ◽  
Large Scale ◽  
Conformational State ◽  
Ctp Synthase ◽  
Widespread Phenomenon ◽  
And Control ◽  
Allosteric Regulators ◽  
Low Activity

Many enzymes assemble into defined oligomers, providing a mechanism for cooperatively regulating enzyme activity. Recent studies in tissues, cells, and in vitro have described a mode of regulation in which enzyme activity is modulated by polymerization into large-scale filaments1–5. Enzyme polymerization is often driven by binding to substrates, products, or allosteric regulators, and tunes enzyme activity by locking the enzyme in high or low activity states1–5. Here, we describe a unique, ultrasensitive form of polymerization-based regulation employed by human CTP synthase 2 (CTPS2). High-resolution cryoEM structures of active and inhibited CTPS2 filaments reveal the molecular basis of this regulation. Rather than selectively stabilizing a single conformational state, CTPS2 filaments dynamically switch between active and inactive filament forms in response to changes in substrate and product levels. Linking the conformational state of many CTPS2 subunits in a filament results in highly cooperative regulation, greatly exceeding the limits of cooperativity for the CTPS2 tetramer alone. The structures also reveal a link between conformational state and control of ammonia channeling between the enzyme’s two active sites. This filament-based mechanism of enhanced cooperativity demonstrates how the widespread phenomenon of enzyme polymerization can be adapted to achieve different regulatory outcomes.

scholarly journals Construction of a novel UDP-rhamnose regeneration system by a two-enzyme reaction system and application in glycosylation of flavonoid

2018 ◽  
Vol 139 ◽  
pp. 33-42 ◽  
Author(s):  
Jianjun Pei ◽  
Anna Chen ◽  
Qing Sun ◽  
Linguo Zhao ◽  
Fuliang Cao ◽  
...  
Keyword(s):  
Reaction System ◽  
Enzyme Reaction ◽  
Regeneration System

The Scalability of Wet Ball Milling for The Production of Nanosuspensions

2019 ◽  
Vol 7 (2) ◽  
pp. 147-161 ◽  
Author(s):  
Maria L.A.D. Lestari ◽  
Rainer H. Müller ◽  
Jan P. Möschwitzer
Keyword(s):  
Ball Milling ◽  
Large Scale ◽  
Milling Time ◽  
High Energy ◽  
Small Scale ◽  
Particle Sizes ◽  
Scale Production ◽  
Batch Mode ◽  
Pharmaceutical Ingredients ◽  
Large Scale Production

Background: Miniaturization of nanosuspensions preparation is a necessity in order to enable proper formulation screening before nanosizing can be performed on a large scale. Ideally, the information generated at small scale is predictive for large scale production. Objective: This study was aimed to investigate the scalability when producing nanosuspensions starting from a 10 g scale of nanosuspension using low energy wet ball milling up to production scales of 120 g nanosuspension and 2 kg nanosuspension by using a standard high energy wet ball milling operated in batch mode or recirculation mode, respectively. Methods: Two different active pharmaceutical ingredients, i.e. curcumin and hesperetin, have been used in this study. The investigated factors include the milling time, milling speed, and the type of mill. Results: Comparable particle sizes of about 151 nm to 190 nm were obtained for both active pharmaceutical ingredients at the same milling time and milling speed when the drugs were processed at 10 g using low energy wet ball milling or 120 g using high energy wet ball milling in batch mode, respectively. However, an adjustment of the milling speed was needed for the 2 kg scale produced using high energy wet ball milling in recirculation mode to obtain particle sizes comparable to the small scale process. Conclusion: These results confirm in general, the scalability of wet ball milling as well as the suitability of small scale processing in order to correctly identify the most suitable formulations for large scale production using high energy milling.

scholarly journals Immobilization of Isocitrate Dehydrogenase on Mesoporous Silica Foam for Carbon Dioxide Capture

2019 ◽  
Vol 93 ◽  
pp. 04001
Author(s):  
Shunxiang Xia ◽  
Laibao Zhang ◽  
Enjelia Veony
Keyword(s):  
Enzyme Activity ◽  
Mesoporous Silica ◽  
Isocitrate Dehydrogenase ◽  
Carbon Capture ◽  
Large Scale ◽  
Enzyme Stability ◽  
Environmental Parameters ◽  
Capture Process ◽  
Dehydrogenase Reaction ◽  
Improved Stability

Carbon capture can be realized effectively through isocitrate dehydrogenase reaction and the reaction rate was strongly affected by the environmental parameters such as pH and temperature. Enzyme immobilization was conducted to improve the enzyme stability during the capture process. By simply adsorbing enzyme on the surface of mesoporous silica foam, enzyme stability against temperature, pH and shear stress was improved. The immobilization process can be completed in 5 mins, and 0.87 U enzyme activity was kept for each gram of immobilization material. After 10 cycles, more than 50 percent of enzyme activity remained. The reusability and improved stability made immobilized ICDH a better candidate for large-scale application of carbon capture.

scholarly journals Micromixing Study of a Clustered Countercurrent-Flow Micro-Channel Reactor and Its Application in the Precipitation of Ultrafine Manganese Dioxide

Micromachines ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 549
Author(s):  
Kun-Peng Cheng ◽  
Bo Wu ◽  
Ren-Jie Gu ◽  
Li-Xiong Wen
Keyword(s):  
Manganese Dioxide ◽  
Ultrafine Particles ◽  
Large Scale ◽  
Reaction System ◽  
Major Effect ◽  
Operating Conditions ◽  
Countercurrent Flow ◽  
Micro Channel ◽  
Channel Reactor ◽  
Particle Structure

A clustered countercurrent-flow micro-channel reactor (C-CFMCR) has been assembled by the numbering-up of its single counterpart (S-CFMCR). Its micromixing performance was then studied experimentally using a competitive parallel reaction system, and the micromixing time was calculated as the micromixing performance index. It was found that the micromixing time of C-CFMCR was ranged from 0.34 to 10 ms according to its numbering-up times and the operating conditions of the reactor, and it was close to that of S-CFMCR under the same operating conditions, demonstrating a weak scaling-up effect from S-CFMCR to C-CFMCR. The C-CFMCR was then applied to prepare ultrafine manganese dioxide in a continuous manner at varying micromixing time. It showed that the micromixing time had a major effect on the particle structure. More uniform and smaller MnO2 particles were obtained with intensified micromixing. By building a typical three electrode system to characterize their performance as a supercapacitor material, the MnO2 particles prepared by both S-CFMCR and C-CFMCR under optimal conditions displayed a specific capacitance of ~175 F·g−1 at the current density of 1 A·g−1, with a decline of ~10% after 500 charge-discharge cycles. This work showed that C-CFMCR will have a great potential for the continuous and large-scale preparation of ultrafine particles.

Proximity Effect in Arene Pi-Complex Formation

1966 ◽  
Vol 21 (9) ◽  
pp. 823-827 ◽  
Author(s):  
Minoru Tsutsui ◽  
Morris N. Levy
Keyword(s):  
Complex Formation ◽  
Proximity Effect ◽  
Grignard Reagent ◽  
Reaction System ◽  
Coupling Reaction ◽  
Reaction Products ◽  
Hydrogen Elimination ◽  
Trans Stilbene ◽  
Π Complex ◽  
Aryl Grignard Reagent

A proximity effect in arene π-complex formation from the reaction system of an aryl Grignard reagent and anhydrous chromic chloride was investigated. The yields of arene π-complexes and any accompanying reaction products were compared by the systematic variation of the aryl Grignard reagent employed. Phenyl Grignard gave the best yield of π-complex followed by the benzyl, mesityl and β-ethyl phenyl analogues. The styryl and phenylacetylenyl analogues did not form any π-complexes.The coupling reaction of benzyl groups gave a new π-complex, π-bibenzyl-π-toluene chromium, along with toluene, bibenzyl and trans-stilbene.Trans-stilbene was found without forming a trace amount of cis-stilbene. A mechanism for this stereospecific and α-hydrogen elimination coupling reaction is proposed.

scholarly journals Large-Scale Production of Salt Fortified with Iodine and Iron

1996 ◽  
Vol 17 (1) ◽  
pp. 1-6 ◽  
Author(s):  
S. Ranganathan ◽  
Vinodini Reddy ◽  
P. Ramamoorthy
Keyword(s):  
Potassium Iodide ◽  
Large Scale ◽  
Ferrous Sulphate ◽  
Sodium Hexametaphosphate ◽  
Common Salt ◽  
Scale Production ◽  
Mixing Process ◽  
Potassium Iodate ◽  
Large Scale Production ◽  
Dry Mixing

A new dry-mixing process for producing iodine- and iron-fortified salt on a large scale (20 30 metric tons per shift) was developed in salt factories at Valinokkam and Hyderabad, India. Common salt is mixed with 1% sodium hexametaphosphate, 0.5% ferrous sulphate heptahydrate, and 0.0055% potassium iodide or 0.007% potassium iodate in a ribbon blender. Dry mixing is superior to spray mixing and is associated with no operational problems. The fortified salt produced by this method retains the original colour of the unfortified salt, and the distribution of iodine and iron is uniform. The acceptability of the fortified salt is satisfactory, as various food preparations using the product are indistinguishable in colour, taste, and flavour from those containing unfortified salt

Numerical Model of a Single Phase, Regenerative Fuel Cell

2004 ◽  
Author(s):  
A. Garrard ◽  
S. Beck ◽  
P. Styring
Keyword(s):  
Fuel Cell ◽  
Large Scale ◽  
Single Phase ◽  
Reaction System ◽  
Reduction Reaction ◽  
Dynamic Calculation ◽  
Species Concentration ◽  
Physical Interactions ◽  
Regenerative Fuel Cell ◽  
Future Work

A code for numerical simulating the fluid flow and electrochemistry of a single phase regenerative fuel cell is presented. Due to the potentially tiny geometries and complex multi-physical interactions, modeling presents a chance to obtain detailed quantitative data and much needed understanding about physics within the reactor. The Regenesys XL200 fuel cell has the industrial application of large scale energy storage and is the focus of this work. A two dimensional, binary reduction reaction system has been created to represent the XL200 and test the code. Commercially available CFD software Fluent was used to calculate the flow field and subroutines were used to create the dynamic calculation of electrochemistry at the reaction surface. The effect of changing the total applied potential across the domain on the potential and species concentration distribution within the domain was investigated. Results show that the code is producing qualitatively feasible results that represent the tight multi-physical coupling. The code is currently not validated against physical experimental results and this will be the focus of future work.

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