scholarly journals Improvement of fucosylated oligosaccharides synthesis by α- L -fucosidase from Thermotoga maritima in water-organic cosolvent reaction system

2021 ◽  
Author(s):  
Mónica Robles-Arias ◽  
Mariano García-Garibay ◽  
Sergio Alatorre-Santamaría ◽  
Salvador R Tello-Solís ◽  
Francisco Guzmán-Rodriguez ◽  
...  
Keyword(s):  
Dimethyl Sulfoxide ◽  
Thermotoga Maritima ◽  
Reaction System ◽  
Hydrolysis Rate ◽  
Optimum Conditions ◽  
Reaction Systems ◽  
Transglycosylation Activity ◽  
Organic Cosolvent ◽  
Ph Range ◽  
Reaction Media

Abstract The effects of water activity (aw), pH, and temperature on transglycosylation activity of α-L-fucosidase from Thermotoga maritima in the synthesis of fucosylated oligosaccharides were evaluated using different water - organic cosolvent reaction systems. The optimum conditions of transglycosylation reaction were the pH range between 7 and 10, and temperature 90–95°C. The addition of organic cosolvent decreased α-L-fucosidase transglycosylation activity in the following order: acetone > dimethyl sulfoxide (DMSO) > acetonitrile (0.51 > 0.42 > 0.18 mM/h). However, the presence of DMSO and acetone enhanced enzyme-catalyzed transglycosylation over hydrolysis as demonstrated by the obtained transglycosylation/hydrolysis rate (rT/H) values of 1.21 and 1.43, respectively. The lowest rT/H was calculated for acetonitrile (0.59), though all cosolvents tested improved the transglycosylation rate in comparison to a control assay (0.39). Overall, the study allowed the production of fucosylated oligosaccharides in water-organic cosolvent reaction media using α-L-fucosidase from Thermotoga maritima as biocatalyst.

scholarly journals Improvement of Fucosylated Oligosaccharides Synthesis by α-L-Fucosidase from Thermotoga maritima in Water-Organic Cosolvent Reaction System

2021 ◽  
Author(s):  
Mónica A. Robles-Arias ◽  
Mariano García-Garibay ◽  
Sergio Alatorre-Santamaría ◽  
Salvador R. Tello-Solís ◽  
Francisco Guzmán-Rodriguez ◽  
...  
Keyword(s):  
Thermotoga Maritima ◽  
Reaction System ◽  
Organic Cosolvent

scholarly journals SiCaSMA: An Alternative Stochastic Description via Concatenation of Markov Processes for a Class of Catalytic Systems

Mathematics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1074
Author(s):  
Vincent Wagner ◽  
Nicole Erika Radde
Keyword(s):  
Reaction System ◽  
Stochastic Simulation Algorithm ◽  
Test Bed ◽  
Biochemical Reaction Networks ◽  
Full System ◽  
Catalytic Systems ◽  
Reaction Systems ◽  
Sample Paths ◽  
Alternative Description ◽  
Linear Differential

The Chemical Master Equation is a standard approach to model biochemical reaction networks. It consists of a system of linear differential equations, in which each state corresponds to a possible configuration of the reaction system, and the solution describes a time-dependent probability distribution over all configurations. The Stochastic Simulation Algorithm (SSA) is a method to simulate sample paths from this stochastic process. Both approaches are only applicable for small systems, characterized by few reactions and small numbers of molecules. For larger systems, the CME is computationally intractable due to a large number of possible configurations, and the SSA suffers from large reaction propensities. In our study, we focus on catalytic reaction systems, in which substrates are converted by catalytic molecules. We present an alternative description of these systems, called SiCaSMA, in which the full system is subdivided into smaller subsystems with one catalyst molecule each. These single catalyst subsystems can be analyzed individually, and their solutions are concatenated to give the solution of the full system. We show the validity of our approach by applying it to two test-bed reaction systems, a reversible switch of a molecule and methyltransferase-mediated DNA methylation.

Fenton-like reaction system with an analyte-activated catfish effect for enhanced colorimetric and photothermal dopamine bioassay

The Analyst ◽  
2020 ◽  
Author(s):  
Zhengrong Niu ◽  
Hong-Hong Rao ◽  
Xin Xue ◽  
Mingyue Luo ◽  
Xiuhui Liu ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Advanced Oxidation Processes ◽  
Reaction System ◽  
Reactive Oxygen ◽  
Advanced Oxidation ◽  
Oxygen Species ◽  
Reaction Systems ◽  
Oxidation Processes

Fenton-like reaction systems have been proven to be more efficient as the powerful promoters in advanced oxidation processes (AOPs) due to their resultantly generated reactive oxygen species (ROS) such as...

scholarly journals AmyA, an α-Amylase with β-Cyclodextrin-Forming Activity, and AmyB from the Thermoalkaliphilic Organism Anaerobranca gottschalkii: Two α-Amylases Adapted to Their Different Cellular Localizations†

2005 ◽  
Vol 71 (7) ◽  
pp. 3709-3715 ◽  
Author(s):  
Meike Ballschmiter ◽  
Martin Armbrecht ◽  
Krasimira Ivanova ◽  
Garabed Antranikian ◽  
Wolfgang Liebl
Keyword(s):  
Amino Acid ◽  
Half Life ◽  
Extracellular Enzyme ◽  
Amino Acid Sequences ◽  
Cyclodextrin Glycosyltransferase ◽  
High Similarity ◽  
Ph Optimum ◽  
Transglycosylation Activity ◽  
Optimum Ph ◽  
Ph Range

ABSTRACT Two α-amylase genes from the thermophilic alkaliphile Anaerobranca gottschalkii were cloned, and the corresponding enzymes, AmyA and AmyB, were investigated after purification of the recombinant proteins. Based on their amino acid sequences, AmyA is proposed to be a lipoprotein with extracellular localization and thus is exposed to the alkaline milieu, while AmyB apparently represents a cytoplasmic enzyme. The amino acid sequences of both enzymes bear high similarity to those of GHF13 proteins. The different cellular localizations of AmyA and AmyB are reflected in their physicochemical properties. The alkaline pH optimum (pH 8), as well as the broad pH range, of AmyA activity (more than 50% activity between pH 6 and pH 9.5) mirrors the conditions that are encountered by an extracellular enzyme exposed to the medium of A. gottschalkii, which grows between pH 6 and pH 10.5. AmyB, on the other hand, has a narrow pH range with a slightly acidic pH optimum at 6 to 6.5, which is presumably close to the pH in the cytoplasm. Also, the intracellular AmyB is less tolerant of high temperatures than the extracellular AmyA. While AmyA has a half-life of 48 h at 70°C, AmyB has a half-life of only about 10 min at that temperature, perhaps due to the lack of stabilizing constituents of the cytoplasm. AmyA and AmyB were very similar with respect to their substrate specificity profiles, clearly preferring amylose over amylopectin, pullulan, and glycogen. Both enzymes also hydrolyzed α-, β-, and γ-cyclodextrin. Very interestingly, AmyA, but not AmyB, displayed high transglycosylation activity on maltooligosaccharides and also had significant β-cyclodextrin glycosyltransferase (CGTase) activity. CGTase activity has not been reported for typical α-amylases before. The mechanism of cyclodextrin formation by AmyA is unknown.

scholarly journals Kinetics of Enzymatic Hydrolysis of Southeast Sulawesi Sago Starch

2020 ◽  
pp. 53-61
Author(s):  
Ansharullah Ansharullah ◽  
Muhammad Natsir
Keyword(s):  
Enzymatic Hydrolysis ◽  
Maximum Velocity ◽  
Enzyme Concentration ◽  
Hydrolysis Rate ◽  
Sago Starch ◽  
Optimum Conditions ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Substrate Concentrations ◽  
Menten Constant

The aims of this study were to characterize the kinetics of enzymatic hydrolysis of sago starch, obtained from Southeast Sulawesi Indonesia. The enzyme used for hydrolysis was bacterial ∝-amylase (Termamyl 120L from Bacillus licheniformis, E. C. 3.2.1.1).  The method to determine the initial velocity (Vo) of the hydrolysis was developed by differentiation a nonlinear equation (NLE).  The Vo of the hydrolysis was measured at various pH (6.0, 6.5,and 7.0), temperatures (40, 60, 75 and 95oC), enzyme concentrations (0.5, 1.0, 1.5 and 2.0 µg per mL) and in the presence of 70 ppm Ca++. The optimum conditions of this experiment were found to be at pH 6.5 – 7.0 and 75oC, and the Vo increased with increasing enzyme concentration. The Vo values at various substrate concentrations were also determined, which were then used to calculate the enzymes kinetics constant of the hydrolysis, including Michaelis-Menten constant (Km) and maximum velocity (Vmax) using a Hanes plot.  Km and Vmax values were found to be higher in the measurement at pH 7.0 and 75oC. The Km values  at four  different combinations of pH and temperatures (pH 6.5, 40oC; pH 6.5, 75oC; pH 7.0, 40oC; pH 7.0, 75oC) were found to be 0.86, 3.23, 0.77 and 3.83 mg/mL, respectively; and Vmax values were 17.5, 54.3, 20.3 and 57.1 µg/mL/min, respectively. The results obtained showed that hydrolysis rate of this starch was somewhat low.

Networks of Reaction Systems

2020 ◽  
Vol 31 (01) ◽  
pp. 53-71 ◽  
Author(s):  
Paolo Bottoni ◽  
Anna Labella ◽  
Grzegorz Rozenberg
Keyword(s):  
Reaction System ◽  
Reaction Systems

In this paper, we study the behavior (processes) of reaction systems where the context is not arbitrary, but it has its own structure. In particular, we consider a model where the context for a reaction system originates from a network of reaction systems. Such a network is formalized as a graph with reaction systems residing at its nodes, where each reaction system contributes to defining the context of all its neighbors. This paper provides a framework for investigating the behavior of reaction systems receiving contexts from networks of reaction systems, provides a characterisation of their state sequences, and considers different topologies of context networks.

scholarly journals Coarse-graining via EDP-convergence for linear fast-slow reaction systems

2020 ◽  
Vol 30 (09) ◽  
pp. 1765-1807 ◽  
Author(s):  
Alexander Mielke ◽  
Artur Stephan
Keyword(s):  
Detailed Balance ◽  
Reaction System ◽  
Gradient Flow ◽  
Coarse Graining ◽  
Reaction Rates ◽  
Coarse Grained ◽  
Gradient Structure ◽  
Reaction Systems ◽  
Fast Reactions ◽  
Finite State

We consider linear reaction systems with slow and fast reactions, which can be interpreted as master equations or Kolmogorov forward equations for Markov processes on a finite state space. We investigate their limit behavior if the fast reaction rates tend to infinity, which leads to a coarse-grained model where the fast reactions create microscopically equilibrated clusters, while the exchange mass between the clusters occurs on the slow time scale. Assuming detailed balance the reaction system can be written as a gradient flow with respect to the relative entropy. Focusing on the physically relevant cosh-type gradient structure we show how an effective limit gradient structure can be rigorously derived and that the coarse-grained equation again has a cosh-type gradient structure. We obtain the strongest version of convergence in the sense of the Energy-Dissipation Principle (EDP), namely EDP-convergence with tilting.

Buffer capacity in multiple chemical reaction systems involving solid phases

2006 ◽  
Vol 84 (8) ◽  
pp. 1036-1044 ◽  
Author(s):  
Ilie Fishtik ◽  
Igor Povar
Keyword(s):  
Chemical Reaction ◽  
Buffer Capacity ◽  
Reaction System ◽  
Chemical Species ◽  
Abundant Species ◽  
Stoichiometric Coefficient ◽  
Reaction Systems ◽  
Chemical Reaction Systems ◽  
Chemical Reaction System ◽  
Multiple Chemical

The buffer capacity of a chemical species in a multiple chemical reaction system is discussed in terms of a special class of stoichiometrically unique reactions referred to as response reactions (RERs). More specifically, it is shown that the buffer capacity may be partitioned into a sum of contributions associated with RERs. This finding provides a deeper understanding of the factors that determine the buffer capacity. In particular, the main contributions to the buffer capacity come from the RERs involving the most abundant species. Concomitantly, the RERs approach provides a simple stoichiometric algorithm for the derivation and analysis of the buffer capacity that may be easily implemented into a computer software.Key words: buffer capacity, response reaction, heterogeneous system, stoichiometric coefficient.

Hydrolysis of BNPP Catalyzed by the Dodecyliminodiacetate Nickel(II) and Copper(II) Complexes

2013 ◽  
Vol 749 ◽  
pp. 507-511
Author(s):  
Sheng Tian Huang ◽  
Shen Xin Li ◽  
Ying Wang ◽  
Song Wu ◽  
Wei Hu
Keyword(s):  
Kinetic Parameter ◽  
Temperature Effect ◽  
Absorption Spectra ◽  
Reaction System ◽  
Catalytic Hydrolysis ◽  
Specific Absorption ◽  
Reaction Systems ◽  
Nitrophenyl Phosphate ◽  
Hydrolytic Reaction ◽  
Hydrolysis Of

Two novel dodecyliminodiacetate nickel (II) and copper (II) complexes were synthesized and characterized, and these complexes were used as mimic hydrolytic in catalytic hydrolysis of bis (p-nitrophenyl) phosphate (BNPP). The analysis of specific absorption spectra of the hydrolytic reaction systems indicated that the catalytic hydrolysis involved the key intermediates formed by BNPP with nickel (II) complexes. The kinetic parameter of BNPP catalytic hydrolysis has been calculated and the temperature effect of reaction system and structure effect of the complexes on the rate of BNPP hydrolysis catalyzed by the complexes have been discussed.

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