A novel approach for bioconjugation of Rhizomucor miehei lipase (RML) onto amine-functionalized supports; Application for enantioselective resolution of rac-ibuprofen

Purification and immobilization of β-glucosidase using surface modified mesoporous silica Santa Barbara Amorphous 15 for eco-friendly preparation of sagittatoside A

Functionalized mesoporous materials have become a promising carrier for enzyme immobilization. In this study, Santa Barbara Amorphous 15 (SBA-15) was modified by N-aminoethyl-γ-aminopropyl trimethoxy (R). R-SBA-15 was employed to purify and immobilize recombinant β-glucosidase from Terrabacter ginsenosidimutans (BgpA) in one step for the first time. Optimum pH of the constructed R-SBA-15@BgpA were 7.0, and it has 20 ℃ higher optimal temperature than free enzyme. Relative activity of R-SBA-15@BgpA still retained > 70% at 42 ℃ after 8-h incubation. The investigation on organic reagent resistance revealed that the immobilized enzyme can maintain strong stability in 15% DMSO. In leaching test and evaluation of storage stability, only trace amount of protein was detected in buffer of the immobilized enzyme after storage at 4 ℃ for 33 days, and the immobilized BgpA still maintained > 50% relative activity. It also demonstrated good reusability, with 76.1% relative activity remaining after fourteen successive enzymatic hydrolyses of epimedin A to sagittatoside A. The newly proposed strategy is an effective approach for the purification and immobilization of BgpA concurrently. In addition, R-SBA-15@BgpA was demonstrated to have high efficiency and stability in this application, suggesting its great feasibility and potential to produce bioactive compounds such as secondary glycosides or aglycones from natural products.

Adsorption-precipitation-cross-linking immobilization of GDSL-type esterase from Aspergillus niger GZUF36 by polydopamine-modified magnetic clarity tetroxide nanocouplings and its enzymatic characterization

Recombinant INANE1 (rINANE1), a recombinant intracellular GDSL-type esterase from Aspergillus niger GZUF36, has high acetate substrate specificity. Here, rINANE1 was successfully immobilized on polydopamine (PDA)-modified magnetic ferric oxide nanoparticles (Fe₃O₄NPs) by adsorption-precipitation-cross-linking to obtain cross-linked enzyme aggregate (CLEA)-rINANE1-Fe₃O₄@PDA. Fe₃O₄, Fe₃O₄@PDA, and CLEA-rINANE1-Fe₃O₄@PDA were characterized by scanning electron microscopy, X-ray diffraction, vibrating-sample magnetometry, Fourier transform infrared (FTIR) spectroscopy, and zeta potential analysis. Upon immobilization, CLEA-rINANE1-Fe₃O₄@PDA, with a protein loading of 72.72 ± 1.01 mg/g, reached optimal activity recovery of 104.40 % ± 1.14 %. FTIR analysis showed that immobilization increased the relative content of β-folding in rINANE1 by 12.25 % and reduced irregular curl by 4.16 %, rendering the structure more orderly. Specifically, under an alkaline condition (pH 10), CLEA-rINANE1-Fe₃O₄@PDA performed over 100 % of initial activity. The optimum temperature increased by 5 °C, and over 55 % of the initial activity was observed after 12 h at 55 °C. CLEA-rINANE1-Fe₃O₄@PDA showed over 40 % of its relative activity, whereas free rINANE1 showed <10 % in acetonitrile. In addition, the relative activity of CLEA-rINANE1-Fe₃O₄@PDA was retained at about 80 % after eight cycles and maintained at 109 % after 45 days. The PDA-modified magnetic ferrite nanoparticles exhibited excellent stability and recyclability, providing a new avenue for developing industrial biocatalysts.

Biocatalytic stereoselective synthesis of pyrrolidine-2,3-diones containing all-carbon quaternary stereocenters

Highly functionalized pyrrolidine-2,3-diones can be synthesized efficiently and stereoselectively under mild conditions using a biocatalytic approach. The reaction led to the formation of new all-carbon quaternary stereocenters from Myceliophthora thermophila laccase (Novozym 51003) catalyzed oxidation of catechols to ortho-quinones and subsequent 1,4-addition with 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones. The reaction was conducted with various substituents on both reactants, resulting in 13 products in moderate to good yields (42-91%). The same 15 reactions were also tested with K₃Fe(CN)₆ as a catalyst, but here only one reaction resulted in a product (60% yield).

Isocyanide-based multi-component reactions for carrier-free and carrier-bound covalent immobilization of enzymes

Strategies for the covalent immobilization of enzymes depend on the type of functional group selected to perform the coupling reaction, and on the relative importance of selectivity, loading capacity, immobilization time and activity/stability of the resulting immobilized preparation. However, no single strategy is applicable for all covalent immobilization methods or can meet all these criteria, exemplifying the challenge of introducing a versatile process broadly compatible with the residues on the surface of proteins and the functional groups of common linkers. Here, we describe the use of isocyanide-based multi-component reactions for the carrier-bound and carrier-free covalent immobilization of enzymes. Isocyanide-based multi-component reactions can accept a wide variety of functional groups such as epoxy, acid, amine and aldehyde, as well as many commercially available bi-functional linkers, and are therefore suitable for either covalent coupling of enzymes on a solid support or intermolecular cross-linking of enzymes. In this strategy, an isocyanide is directly added to the reaction medium, the enzyme supplies either the exposed amine or carboxylic acid groups, and the support (in carrier-bound immobilization) or the bi-functional cross-linking agent (in carrier-free immobilization) provides another reactive functional group. The protocol offers operational simplicity, high efficiency and a notable reduction in time over alternative strategies, and can be performed by users with expertise in chemistry or biology. The immobilization reactions typically require 1-24 h.

Polymer/Enzyme Composite Materials—Versatile Catalysts with Multiple Applications

A significant interest was granted lately to enzymes, which are versatile catalysts characterized by natural origin, with high specificity and selectivity for particular substrates. Additionally, some enzymes are involved in the production of high-valuable products, such as antibiotics, while others are known for their ability to transform emerging contaminates, such as dyes and pesticides, to simpler molecules with a lower environmental impact. Nevertheless, the use of enzymes in industrial applications is limited by their reduced stability in extreme conditions and by their difficult recovery and reusability. Rationally, enzyme immobilization on organic or inorganic matrices proved to be one of the most successful innovative approaches to increase the stability of enzymatic catalysts. By the immobilization of enzymes on support materials, composite biocatalysts are obtained that pose an improved stability, preserving the enzymatic activity and some of the support material’s properties. Of high interest are the polymer/enzyme composites, which are obtained by the chemical or physical attachment of enzymes on polymer matrices. This review highlights some of the latest findings in the field of polymer/enzyme composites, classified according to the morphology of the resulting materials, following their most important applications.

Sortase-mediated immobilization of Candida antarctica lipase B (CalB) on graphene oxide; comparison with chemical approach

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Sortase A was used for the oriented immobilization of CalB on graphene oxide nanosheets

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Random attachment of CalB on GO nanosheets were performed by chemical immobilization

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The immobilized CalB were used for the enrichment of omega-3 fatty acids in fish oil

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The derivative obtained from oriented immobilization showed improved selectivity

In this study, Candida antarctica lipase B (CalB) was covalently immobilized on the surface of graphene oxide (GO) nanoparticles by sortase-mediated immobilization as well as a chemical attachment approach. Sortase is a transpeptidase that provides one-step purification and targeted immobilization of CalB from one specific site, presenting oriented attachment of the enzyme to a solid support. Chemical immobilization, on the other hand, is considered as a random immobilization, in which the protein can bind to the support from different regions of the protein surface. In this approach, amine-functionalized GO was further modified with glutaraldehyde to facilitate the covalent binding of CalB via its amine residues. The applied methods produced 60% and 100% immobilization yields and presented 0.106 U/mg and 0.085 U/mg of specific activities for the oriented and random immobilization, respectively. The stabilized enzyme with the sortase-mediated approach retained approximately 80% of its initial activity at 50°C.

A multi-component reaction for covalent immobilization of lipases on amine-functionalized magnetic nanoparticles: production of biodiesel from waste cooking oil

A new approach was used for the immobilization of Thermomyces lanuginosus lipase (TLL), Candida antarctica lipase B (CALB), and Rhizomucor miehei lipase (RML) on amine-functionalized magnetic nanoparticles (Fe3O4@SiO2-NH2) via a multi-component reaction route (using cyclohexyl isocyanide). The used method offered a single-step and very fast process for covalent attachment of the lipases under extremely mild reaction conditions (25 °C, water, and pH 7.0). Rapid and simple immobilization of 20 mg of RML, TLL, and CALB on 1 g of the support produced 100%, 98.5%, and 99.2% immobilization yields, respectively, after 2 h of incubation. The immobilized derivatives were then used for biodiesel production from waste cooking oil. Response surface methodology (RSM) in combination with central composite rotatable design (CCRD) was employed to evaluate and optimize the biodiesel production. The effect of some parameters such as catalyst amount, reaction temperature, methanol concentration, water content for TLL or water-adsorbent for RML and CALB, and ratio of t-butanol (wt%) were investigated on the fatty acid methyl esters (FAME) yield.

Electrospun Magnetic Nanocellulose-Polyethersulfone-Conjugated Aspergillus oryzae Lipase for Synthesis of Ethyl Valerate

A novel greener MNC/PES membrane was developed through an electrospinning technique for lipase immobilization to catalyze the synthesis of ethyl valerate (EV). In this study, the covalent immobilization of Aspergillus oryzae lipase (AOL) onto an electrospun nanofibrous membrane consisting of magnetic nanocellulose (MNC) and polyethersulfone (PES) to produce EV was statistically optimized. Raman spectroscopy, Fourier-transform infrared spectroscopy: attenuated total reflection, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, thermal gravimetric analysis (TGA), and differential thermal gravimetric (DTG) of MNC/PES-AOL demonstrated that AOL was successfully immobilized onto the fibers. The Taguchi design-assisted immobilization of AOL onto MNC/PES fibers identified that 1.10 mg/mL protein loading, 4 mL reaction volume, 250 rpm stirring rate, and 50 °C were optimal to yield 72.09% of EV in 24 h. The thermal stability of MNC/PES-AOL was improved by ≈20% over the free AOL, with reusability for up to five consecutive esterification cycles while demonstrating an exceptional half-life of 120 h. Briefly, the electrospun MNC/PES fibers that immobilized AOL showed promising applicability in yielding relatively good EV levels. This study suggests that using MNC as fillers in a PES to improve AOL activity and durability for a longer catalytic process could be a viable option.

Different strategies for the lipase immobilization on the chitosan based supports and their applications

Immobilized enzymes have received incredible interests in industry, pharmaceuticals, chemistry and biochemistry sectors due to their various advantages such as ease of separation, multiple reusability, non-toxicity, biocompatibility, high activity and resistant to environmental changes. This review in between various immobilized enzymes focuses on lipase as one of the most practical enzyme and chitosan as a preferred biosupport for lipase immobilization and provides a broad range of studies of recent decade. We highlight several aspects of lipase immobilization on the surface of chitosan support containing various types of lipase and immobilization techniques from physical adsorption to covalent bonding and cross-linking with their benefits and drawbacks. The recent advances and future perspectives that can improve the present problems with lipase and chitosan such as high-price of lipase and low mechanical resistance of chitosan are also discussed. According to the literature, optimization of immobilization methods, combination of these methods with other techniques, physical and chemical modifications of chitosan, co-immobilization and protein engineering can be useful as a solution to overcome the mentioned limitations.

Improvement of biodiesel production from palm oil by co-immobilization of Thermomyces lanuginosa lipase and Candida antarctica lipase B: Optimization using response surface methodology

Candida antarctica lipase B (CALB) and Thermomyces lanuginose lipase (TLL) were co-immobilized on epoxy functionalized silica gel via an isocyanide-based multicomponent reaction. The immobilization process was carried out in water (pH 7) at 25 °C, rapidly (3 h) resulting in high immobilization yields (100%) with a loading of 10 mg enzyme/g support. The immobilized preparations were used to produce biodiesel by transesterification of palm oil. In an optimization study, response surface methodology (RSM) and central composite rotatable design (CCRD) methods were used to study the effect of five independent factors including temperature, methanol to oil ratio, t-butanol concentration and CALB:TLL ratio on the yield of biodiesel production. The optimum combinations for the reaction were CALB:TLL ratio (2.1:1), t-butanol (45 wt%), temperature (47 °C), methanol: oil ratio (2.3). This resulted in a FAME yield of 94%, very close to the predicted value of 98%.

Fine Modulation of the Catalytic Properties of Rhizomucor miehei Lipase Driven by Different Immobilization Strategies for the Selective Hydrolysis of Fish Oil

Functional properties of each enzyme strictly depend on immobilization protocol used for linking enzyme and carrier. Different strategies were applied to prepare the immobilized derivatives of Rhizomucor miehei lipase (RML) and chemically aminated RML (NH₂-RML). Both RML and NH₂-RML forms were covalently immobilized on glyoxyl sepharose (Gx-RML and Gx-NH₂-RML), glyoxyl sepharose dithiothreitol (Gx-DTT-RML and Gx-DTT-NH₂-RML), activated sepharose with cyanogen bromide (CNBr-RML and CNBr-NH₂-RML) and heterofunctional epoxy support partially modified with iminodiacetic acid (epoxy-IDA-RML and epoxy-IDA-NH₂-RML). Immobilization varied from 11% up to 88% yields producing specific activities ranging from 0.5 up to 1.9 UI/mg. Great improvement in thermal stability for Gx-DTT-NH₂-RML and epoxy-IDA-NH₂-RML derivatives was obtained by retaining 49% and 37% of their initial activities at 70 °C, respectively. The regioselectivity of each derivative was also examined in hydrolysis of fish oil at three different conditions. All the derivatives were selective between cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and cis-4,7,10,13,16,19-docosahexaenoic acid (DHA) in favor of EPA. The highest selectivity (32.9 folds) was observed for epoxy-IDA-NH₂-RML derivative in the hydrolysis reaction performed at pH 5 and 4 °C. Recyclability study showed good capability of the immobilized biocatalysts to be used repeatedly, retaining 50-91% of their initial activities after five cycles of the reaction.

Soluble enzyme cross-linking via multi-component reactions: a new generation of cross-linked enzymes

Production of CLEs using a multi-component reaction.

Biodiesel Production (FAEEs) by Heterogeneous Combi-Lipase Biocatalysts Using Wet Extracted Lipids from Microalgae

The production of fatty acids ethyl esters (FAEEs) to be used as biodiesel from oleaginous microalgae shows great opportunities as an attractive source for the production of renewable fuels without competing with human food. To ensure the economic viability and environmental sustainability of the microbial biomass as a raw material, the integration of its production and transformation into the biorefinery concept is required. In the present work, lipids from wet Isochrysis galbana microalga were extracted with ethyl acetate with and without drying the microalgal biomass (dry and wet extraction method, respectively). Then, FAEEs were produced by lipase-catalyzed transesterification and esterification of the extracted lipids with ethanol using lipase B from Candida antarctica (CALB) and Pseudomonas cepacia (PC) lipase supported on SBA-15 mesoporous silica functionalized with amino groups. The conversion to FAEEs with CALB (97 and 85.5 mol% for dry and wet extraction, respectively) and PC (91 and 87 mol%) biocatalysts reached higher values than those obtained with commercial Novozym 435 (75 and 69.5 mol%). Due to the heterogeneous nature of the composition of microalgae lipids, mixtures with different CALB:PC biocatalyst ratio were used to improve conversion of wet-extracted lipids. The results showed that a 25:75 combi-lipase produced a significantly higher conversion to FAEEs (97.2 mol%) than those produced by each biocatalyst independently from wet-extracted lipids and similar ones than those obtained by each lipase from the dry extraction method. Therefore, that optimized combi-lipase biocatalyst, along with achieving the highest conversion to FAEEs, would allow improving viability of a biorefinery since biodiesel production could be performed without the energy-intensive step of biomass drying.

Materials Functionalization with Multicomponent Reactions: State of the Art

The emergence of neoteric synthetic routes for materials functionalization is an interesting phenomenon in materials chemistry. In particular, the union of materials chemistry with multicomponent reactions (MCRs) opens a new avenue leading to the realm of highly innovative functionalized architectures with unique features. MCRs have recently been recognized as considerable part of the synthetic chemist's toolbox due to their great efficiency, inherent molecular diversity, atom and pot economy along with operational simplicity. Also, MCRs can improve E-factor and mass intensity as important green chemistry metrics. By rational tuning of the materials, as well as the MCRs, wide ranges of functionalized materials can be produced with tailorable properties that can play important roles in the plethora of applications. To date, there has not reported any exclusive review of a materials functionalization with MCRs. This critical review highlights the state-of-the-art on the one-pot functionalization of carbonaceous and siliceous materials, polysaccharides, proteins, enzymes, synthetic polymers, etc., via diverse kind of MCRs like Ugi, Passerini, Petasis, Khabachnik-Fields, Biginelli, and MALI reactions through covalent or noncovalent manners. Besides the complementary discussion of synthetic routes, superior properties and detailed applicability of each functionalized material in modern technologies are discussed. Our outlook also emphasizes future strategies for this unprecedented area and their use as materials for industrial implementation. With no doubt, MCRs-functionalization of materials bridges the gap between materials science domain and applied chemistry.