scholarly journals Ability of Ectoine to Stabilize Lipase against Elevated Temperatures and Methanol Concentrations

2021 ◽  
Vol 21 (2) ◽  
pp. 494
Author(s):  
I Putu Parwata ◽  
Deana Wahyuningrum ◽  
Sony Suhandono ◽  
Rukman Hertadi
Keyword(s):  
Catalytic Activity ◽  
Lipase Activity ◽  
Organic Molecules ◽  
Elevated Temperatures ◽  
Residual Activity ◽  
Final Concentration ◽  
Methanol Treatment ◽  
Highly Effective

Ectoine is one of the compatible organic molecules that can protect the protein from heating, freezing, and chemicals contact. This study aims to investigate the ability of ectoine to stabilize lipase on heating and in methanol treatments as an effort to provide a stable biocatalyst for the production of biodiesel. Various ectoine concentrations were added to lipase solutions, then the mixture was heated, and the residual activity of the lipase was determined. Similar steps were also conducted for methanol treatment. The results showed that ectoine maintained and even improved the catalytic activity of lipase after treatment with either heat or methanol. The addition of ectoine to a final concentration of 110 to 150 mM could maintain lipase activity up to 80% when heating to approximately 95 °C. Additionally, more than 20% of lipase activity increased on heating to temperatures below 75 °C in the presence of ectoine at a final concentration of 25 to 120 mM. Meanwhile, after incubation in methanol at a level of around 84% (v/v), the activity of lipase containing 40–90 mM ectoine was maintained. These results demonstrated that ectoine was highly effective in protecting lipase from heat and methanol.

scholarly journals Computational Design of Nitrile Hydratase from Pseudonocardia thermophila JCM3095 for Improved Thermostability

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4806
Author(s):  
Zhongyi Cheng ◽  
Yao Lan ◽  
Junling Guo ◽  
Dong Ma ◽  
Shijin Jiang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Rational Design ◽  
Nitrile Hydratase ◽  
Elevated Temperatures ◽  
Residual Activity ◽  
Fold Increase ◽  
Computational Design ◽  
Site Directed Mutagenesis ◽  
Multiple Point ◽  
Substrate Affinity

High thermostability and catalytic activity are key properties for nitrile hydratase (NHase, EC 4.2.1.84) as a well-industrialized catalyst. In this study, rational design was applied to tailor the thermostability of NHase from Pseudonocardia thermophila JCM3095 (PtNHase) by combining FireProt server prediction and molecular dynamics (MD) simulation. Site-directed mutagenesis of non-catalytic residues provided by the rational design was subsequentially performed. The positive multiple-point mutant, namely, M10 (αI5P/αT18Y/αQ31L/αD92H/βA20P/βP38L/βF118W/βS130Y/βC189N/βC218V), was obtained and further analyzed. The Melting temperature (Tm) of the M10 mutant showed an increase by 3.2 °C and a substantial increase in residual activity of the enzyme at elevated temperatures was also observed. Moreover, the M10 mutant also showed a 2.1-fold increase in catalytic activity compared with the wild-type PtNHase. Molecular docking and MD simulations demonstrated better substrate affinity and improved thermostability for the mutant.

Development of an integrated thermal and enzymatic hydrolysis for lignocellulosic biomass in fixed-bed reactors

Holzforschung ◽  
2011 ◽  
Vol 65 (4) ◽  
Author(s):  
Christian Kirsch ◽  
Carsten Zetzl ◽  
Irina Smirnova
Keyword(s):  
Enzyme Activity ◽  
Enzymatic Hydrolysis ◽  
Lignocellulosic Biomass ◽  
Elevated Temperatures ◽  
Enzyme Stability ◽  
Fixed Bed ◽  
Residual Activity ◽  
Fixed Bed Reactor ◽  
Shear Forces ◽  
Glucose Yield

Abstract The limitations of the current biorefinery process utilizing stirred-tank reactors for the enzymatic step include poor mixing in the case of high biomass loadings, additional steps for the product separation, and a long reaction time. In this study the hydrothermal pretreatment and the enzymatic hydrolysis of the lignocellulosic biomass were combined in one fixed-bed reactor. The influence of the shear forces during recirculation and enzyme stability at elevated temperatures were investigated. It has been shown that the shear forces resulting from pumping have a negligible effect on enzyme activity. However, large pressure drops reduce the enzyme activity significantly. Furthermore, the enzyme stability was significantly increased at elevated temperatures (60°C) by applying static pressures up to 200 bar (56% residual activity at 60°C after 24 h). This is beneficial for the process as a higher temperature accelerates the reaction. Further improvement of the overall process efficiency was achieved by increasing the solid-to-water ratio and circulation of the enzyme solution. At a biomass content of 7%, a glucose concentration of 61 g l-1 and a yield of 85% was achieved. The integrated process was first done on a laboratory scale (50 ml). At 100 bar, 60°C and 10% biomass loading an increased initial reaction rate was observed. However, this effect was followed by the stagnation of the glucose yield as one of the enzymes, Novozyme 188, showed no remarkable stabilization with pressure. Nevertheless, an overall glucose yield of 40% was achieved after 5.5 h, compared to 14 h under normal pressure and 50°C.

A Potentially Polymerizable Heterodinuclear FeIIIZnII Purple Acid Phosphatase Mimic. Synthesis, Characterization, and Phosphate Ester Hydrolysis Studies

2011 ◽  
Vol 64 (3) ◽  
pp. 258 ◽  
Author(s):  
Yoke Leng Michelle Zee ◽  
Lawrence R. Gahan ◽  
Gerhard Schenk
Keyword(s):  
Mass Spectrometry ◽  
Catalytic Activity ◽  
Acid Phosphatase ◽  
Residual Activity ◽  
Purple Acid Phosphatase ◽  
Phosphate Ester ◽  
Ir Spectrometry ◽  
Pka Values ◽  
Phosphate Ester Hydrolysis ◽  
Rate Profile

An analogue of the purple acid phosphatase biomimetic 2-((bis(pyridin-2-ylmethyl)amino)methyl)-6-(((2-hydroxybenzyl)(pyridin-2-ylmethyl)amino)methyl)-4-methylphenol has been synthesized. The analogue, 2-((bis(pyridin-2-ylmethyl)amino)methyl)-6-(((2-hydroxy-4-(4-vinylbenzyloxy)benzyl)(pyridin-2-ylmethyl)amino)methyl)-4-methylphenol (H2BPBPMPV) possesses a pendant olefin suitable for copolymerization. Complexation with FeIII/ZnII resulted in the complex [FeIIIZnII(BPBPMPV)(CH3COO)2](ClO4), characterized with mass spectrometry, microanalysis, UV/vis, and IR spectrometry. The catalytic activity of the complex toward bis-(2,4-dinitrophenyl) phosphate was determined, resulting in Km of 4.1 ± 0.6 mM, with kcat 3.8 ± 0.2 × 10–3 s–1 and a bell-shaped pH–rate profile with pKa values of 4.31, 5.66, 8.96, the profile exhibiting residual activity above pH 9.5.

scholarly journals Poly(catechol) modified Fe3O4 magnetic nanocomposites with continuous high Fenton activity for organic degradation at neutral pH

2021 ◽  
Author(s):  
Yani Hua ◽  
Chuan Wang ◽  
Sha Wang ◽  
Juan Xiao
Keyword(s):  
Catalytic Activity ◽  
Fenton Reaction ◽  
Organic Molecules ◽  
Precipitation Method ◽  
Organic Degradation ◽  
Redox Pair ◽  
Iron Leaching ◽  
Acidic Conditions ◽  
Ph Range ◽  
Co Precipitation

Abstract Fe3O4 magnetic nanoparticles (MNPs) have been widely used as a recyclable catalyst in Fenton reaction for organic degradation. However, the pristine MNPs suffer from the drawbacks of iron leaching in acidic conditions as well as the decreasing catalytic activity of organic degradation at a pH higher than 3.0. To solve the problems, Fe3O4 MNPs were modified by poly(catechol) (Fe3O4/PCC MNPs) using a facile chemical co-precipitation method. The poly(catechol) modification improved both the dispersity and the surface negative charges of Fe3O4/PCC MNPs, which are beneficial to the catalytic activity of MNPs for organics degradation. Moreover, the poly(catechol) modification enhanced the efficiency of Fe(II) regeneration during Fenton reaction due to the acceleration of Fe(III) reduction by the phenolic/quinonoid redox pair. As a result, the Fenton reaction with Fe3O4/PCC MNPs could efficiently degrade organic molecules, exampled by methylene blue (MB), in an expanded pH range between 3.0 and 10.0. In addition, Fe3O4/PCC MNPs could be reused up to 8 cycles for the MB degradation with negligible iron leaching of lower than 1.5 mg L-1. This study demonstrated Fe3O4/PCC MNPs are a promising heterogeneous Fenton catalysts for organic degradation.

scholarly journals Graphene oxide as a catalyst for the diastereoselective transfer hydrogenation in the synthesis of prostaglandin derivatives

2017 ◽  
Vol 53 (74) ◽  
pp. 10271-10274 ◽  
Author(s):  
Simona M. Coman ◽  
Iunia Podolean ◽  
Madalina Tudorache ◽  
Bogdan Cojocaru ◽  
Vasile I. Parvulescu ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Catalytic Activity ◽  
Allyl Alcohol ◽  
Hydrogen Transfer ◽  
Organic Molecules ◽  
Transfer Hydrogenation

Modification of GO by organic molecules changes its catalytic activity in the hydrogen transfer from i-propanol to enones, affecting the selectivity to allyl alcohol and diastereoselectivity to the resulting stereoisomers.

scholarly journals Improved Performance of D-Psicose 3-Epimerase by Immobilisation on Amino-Epoxide Support with Intense Multipoint Attachment

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 831
Author(s):  
Yifan Bu ◽  
Tao Zhang ◽  
Bo Jiang ◽  
Jingjing Chen
Keyword(s):  
Catalytic Activity ◽  
Ion Exchange ◽  
Substrate Specificity ◽  
Covalent Binding ◽  
Residual Activity ◽  
Free Form ◽  
High Catalytic Activity ◽  
Low Calorie ◽  
Reaction Solution ◽  
Improved Performance

D-allulose is an epimer of D-fructose at the C-3 position. With similar sweetness to sucrose and a low-calorie profile, D-allulose has been considered a promising functional sweetener. D-psicose 3-epimerase (DPEase; EC 5.1.3.30) catalyses the synthesis of D-allulose from D-fructose. Immobilised enzymes are becoming increasingly popular because of their better stability and reusability. However, immobilised DPEase generally exhibits less activity or poses difficulty in separation. This study aimed to obtain immobilised DPEase with high catalytic activity, stability, and ease of separation from the reaction solution. In this study, DPEase was immobilised on an amino-epoxide support, ReliZyme HFA403/M (HFA), in four steps (ion exchange, covalent binding, glutaraldehyde crosslinking, and blocking). Glycine-blocked (four-step immobilisation) and unblocked (three-step immobilisation) immobilised DPEase exhibited activities of 103.5 and 138.8 U/g support, respectively, but contained equal amounts of protein. After incubation at 60 °C for 2 h, the residual activity of free enzyme decreased to 12.5%, but the activities of unblocked and blocked DPEase remained at 40.9% and 52.3%, respectively. Immobilisation also altered the substrate specificity of the enzyme, catalysing L-sorbose to L-tagatose and D-tagatose to D-sorbose. Overall, the immobilised DPEase with intense multipoint attachment, especially glycine-blocked DPEase, showed better properties than the free form, providing a superior potential for D-allulose biosynthesis.

Synthesis and Catalytic Evaluation of Ferrierite-Related Materials Synthesized in the Presence of co-Structure Directing Agents

2008 ◽  
Vol 73 (8-9) ◽  
pp. 1089-1104 ◽  
Author(s):  
Raquel García ◽  
Ana Belén Pinar ◽  
Carlos Márquez-Alvarez ◽  
Enrique Sastre ◽  
Joaquín Pérez-Pariente
Keyword(s):  
Catalytic Activity ◽  
Organic Molecules ◽  
Organic Cation ◽  
Zeolite Synthesis ◽  
Structure Directing Agent ◽  
Sodium Cations ◽  
Systematic Exploration ◽  
Structure Directing Agents

We report on the systematic exploration of zeolite synthesis using a combination of organic molecules of different size. The effect of changing the co-structure directing agent, co-SDA, (tetramethylammonium or quinuclidine) and its replacement by sodium cations, when used together with the bulky organic cation 1-benzyl-1-methylpyrrolidinium (bmp) is analyzed and compared with preparations where bmp is replaced by the related cation (S)-1-benzyl-2-hydroxymethyl-1-methylpyrrolidinium (bmprol). The tendency to direct the synthesis to ferrierite or ferrierite-like materials depending on the particular combination of bulky organic cation and co-SDA is discussed. The catalytic activity of some of the materials synthesized was tested in the isomerization of m-xylene.

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