Efficient hydrolysis of starch by α-amylase immobilized on cloisite 30B and modified forms of cloisite 30B by adsorption and covalent methods
TL;DR: In this paper, α-amylase from Bacillus subtilis was successfully immobilized on three supports, and their enzymatic activities were effectively tested in the starch hydrolysis.
About: This article is published in Food Chemistry.The article was published on 2022-03-30. It has received 37 citations till now. The article focuses on the topics: Epichlorohydrin & Amylase.
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TL;DR: A boosted photocatalytic activity was observed for the CdS-AgBr nanocomposite in the degradation of methylene blue (MB) and analysis of variance of the results confirmed a significant model for processing the data.
44 citations
TL;DR: In this article , a facile hydrothermal technique was used to prepare a novel quadripartite SnO2@TiO2/ZrTiO4/ZRO2 (STZZ) photocatalyst, and the photocatalytic activity of STZZ was successfully tested in the metronidazole (MNZ) photodegradation under UV irradiation in water.
19 citations
TL;DR: In this paper , the synergistic photocatalytic activity was obtained when CdS and BiVO4 nanoparticles (NPs) were coupled, and the experimental data was characterized by XRD, FTIR, SEM-EDX, and UV-DRS techniques, and their pHpzc was also estimated.
18 citations
TL;DR: In this article , a binary BiOI/(BiO) 2 CO 3 catalyst was prepared via the co-precipitation process as a typical bismuth-based photocatalyst.
16 citations
TL;DR: In this paper , a coupled CdS/BiVO4 coupled catalyst was prepared via mechanical mixing of the as-synthesized cdS and BiVO4 NPs, which achieved a boosted photocatalytic activity in the photodegradation of EBT (Eriochrome Black T).
13 citations
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TL;DR: This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr with little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose.
225,085 citations
TL;DR: In this article, the authors highlight several aspects of lipase-catalyzed biodiesel production and discuss the possible solutions to circumvent the well-known problems inherent in these systems, such as the low-stability and the pricing of biocatalysts.
153 citations
TL;DR: Bovine trypsin has been immobilized on glyoxyl-agarose and two different preparations have been produced, suggesting that the inactivation ways were different for each enzyme preparation and dependent on the in activation conditions.
Abstract: Bovine trypsin has been immobilized on glyoxyl-agarose and two different preparations have been produced. One was reduced just after immobilization, while the other was left to continue the enzyme-support reaction. This strategy is a guarantee of the identical orientation of the enzyme regarding the support surface and the identical physical properties of the support. Then, the two preparations were submitted to inactivations under different conditions: thermal and solvent inactivations under different pH values. After drying, the structures of the different enzymes preparations were analyzed by deconvolution of the amide I region, which provides information about the secondary structure of the protein in terms of α-helixes, β-sheets, β-turns and non-ordered or irregular structures. The results confirm that the structures of the different preparations were very different, suggesting that the inactivation ways were different for each enzyme preparation and dependent on the inactivation conditions. This information is very relevant for the design of strategies for enzyme stabilization, as shown by the fact that the inactivation may follow different conformational changes depending on the degree of enzyme rigidification and inactivation conditions.
138 citations
TL;DR: In this paper, a nanohybrid material was developed and used for the first time to the kinetic resolution of secondary alcohols as rac-indanol, rac-1-phenylethanol (rac-1), rac-3-bromophenyl)-1-ethanol(rac-2), and rac-4.
Abstract: In this work, a nanohybrid material was developed and used for the first time to the kinetic resolution of secondary alcohols as rac-indanol, rac-1-phenylethanol (rac-1), rac-1-(3-bromophenyl)-1-ethanol (rac-2) and rac-1-(3-methylphenyl)-1-ethanol (rac-3). Chiral indanol is used as a precursor intermediate for the synthesis of enantiomeric drugs, such as (+)-Indatraline, Irindalone, Indinavir, (+)-Sertraline and Rasagiline mesylate. Chiral 1-phenylethanol is used as an ophthalmic preservative, a solvatochromic dye and an inhibitor of cholesterol absorption and as a mild floral fragrance. For this purpose, the ultrasound irradiation was used to couple APTES on the superparamagnetic nanoparticles surface. Then, the system was activated with glutaraldehyde and used as a support for immobilization of lipase from Pseudomonas fluorescens. Thermal stability analysis was performed in buffer and hexane, showing an excellent stability in buffer solution at 60 °C, holding 72% of the initial activity, even after 7 h. In hexane (40 °C), the immobilized enzyme retained 100% of activity with 693 min of half-life time at 50 °C. The high thermal stability is mainly related to the covalent bonding between enzymes and support. Immobilized lipase on magnetic support proved to be a robust biocatalyst in the kinetic resolution, leading to (S)-indanol with high selectivity (e.e. > 99%, E > 200) in 1.75 h at 50 °C, being reused five times without significant loss of the activity and selectivity. The kinetic resolution of rac-1, via acetylation reaction, catalyzed by lipase from Pseudomonas fluorescens immobilized on magnetic support, led to (R)-acetate with enantiomeric excess > 99% and to the remaining (S)-alcohol with enantiomeric excess of 94%, conversion of 49% and E > 200, after 48 h of reaction at 40 °C. Under the same reactions conditions, rac-2 and rac-3 were slightly less reactive, since the corresponding (R)-acetates were obtained with conversion values of 44%, but with high enantioselectivity (enantiomeric excesses > 99% and E values > 200). These results correspond to an important step in heterogeneous catalysis due to the ability to obtain important precursors for the synthesis of enantiomerically pure chiral drugs and other bioactive substances.
130 citations
TL;DR: The CALB‐IB‐350 thermal and solvent stabilities were higher than that of the soluble enzyme and the enantiomeric excess of the product was 97%.
Abstract: Novozyme 435, which is a commercial immobilized lipase B from Candida antarctica (CALB), has been proven to be inadequate for the kinetic resolution of rac-indanyl acetate. As it has been previously described that different immobilization protocols may greatly alter lipase features, in this work, CALB was covalently immobilized on epoxy Immobead-350 (IB-350) and on glyoxyl-agarose to ascertain if better kinetic resolution would result. Afterwards, all CALB biocatalysts were utilized in the hydrolytic resolution of rac-indanyl acetate and rac-(chloromethyl)-2-(o-methoxyphenoxy) ethyl acetate. After optimization of the immobilization protocol on IB-350, its loading capacity was 150 mg protein/g dried support. Furthermore, the CALB-IB-350 thermal and solvent stabilities were higher than that of the soluble enzyme (e.g., by a 14-fold factor at pH 5-70°C and by a 11-fold factor in dioxane 30%-65°C) and that of the glyoxyl-agarose-CALB (e.g., by a 12-fold factor at pH 10-50°C and by a 21-fold factor in dioxane 30%-65°C). The CALB-IB-350 preparation (with 98% immobilization yield and activity versus p-nitrophenyl butyrate of 6.26 ± 0.2 U/g) was used in the hydrolysis of rac-indanyl acetate using a biocatalyst/substrate ratio of 2:1 and a pH value of 7.0 at 30°C for 24 h. The conversion obtained was 48% and the enantiomeric excess of the product (e.e.p ) was 97%. These values were much higher than the ones obtained with Novozyme 435, 13% and 26% of conversion and e.e.p, respectively. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:878-889, 2018.
106 citations