A model for interfacial activation in lipases from the structure of a fungal lipase-inhibitor complex

Selective production of functional sn-1,3-diacylglycerol by microbial lipases: A comprehensive review

Since early 1990s, diacylglycerol (DAG) has drawn a continuous trending interest among researchers and oil industries/markets as part of a reduced-energy diet due to its functions to prevent and manage obesity. With the accumulated knowledge, a stereoisomer of sn-1,3-DAG is regarded as the sole compound to contribute to DAG's functions. sn-1,3-DAG can be produced by direct esterification of free fatty acids and glycerol, partial hydrolysis of TAGs/edible oils, and glycerolysis of TAGs/edible oils with glycerol using the regioselective microbial lipases as the catalyst. However, the specific microbial lipases with high efficiency to produce sn-1,3-DAG and their catalytic mechanisms are still a mystery. Herein, we provide an overview of metabolic fates of three stereoisomers of DAGs including sn-1,3-DAG, sn-1,2-DAG and/or sn-2,3-DAG, and synthesis process for sn-1,3-DAG, and critically outline the microbial lipases to selectively produce sn-1,3-DAG, and their pathways and mechanisms, which hopefully presents a reasonable full picture of functions, synthesis schemes, and catalytic performance to improve regioselectivity and catalytic efficiency for sn-1,3-DAG production with high yield.

Enhancing cryo-enzymatic efficiency in cold-adapted lipase from Psychrobacter sp. C18 via site-directed mutagenesis

As industrial demands for cold-active enzymes have been increased, psychrophilic lipases present a promising solution with potential for innovation and growth in food, pharmaceutical, and detergent industries. Cold-adapted enzymes achieve high catalytic efficiency at low temperatures through their structural flexibility and conformational adaptability. Therefore, in this study, the lipase gene from Psychrobacter sp. C18 was cloned and subjected to site-directed mutagenesis based on computer aided predictions to enhance the enzyme's cold-adapted properties and flexibility. Mutations were strategically selected in loops of the active site to improve the enzyme's accessibility to the substrate under cold conditions. The P163G, L186G, and Q239W mutations were selected for further analysis. Enzyme activity, along with its stability and structural flexibility, was assessed using techniques including UV-Vis spectroscopy, fluorescence, and circular dichroism (CD) spectroscopy. The obtained data revealed that the optimal temperature for the wild-type lipase was 30 °C, which shifted to lower temperatures in the mutants: 15 °C for P163G and L186G, and 20 °C for Q239W. Additionally, the optimal pH of the mutant lipases shifted to more alkaline conditions compared to the wild-type enzyme. While the thermal and pH stability of the mutant enzymes slightly decreased, these findings can be attributed to their enhanced flexibility. Far-UV CD spectroscopy revealed a reduction in α-helical content of the mutant enzymes. Molecular dynamics simulations corroborated these findings, confirming increased structural flexibility in all three mutants compared to the wild-type enzyme. This research underlines the importance of applying engineered cold-adapted enzymes for industrial application.

Novel Immobilized Enzyme System Using Hydrophobic Dendritic Mesoporous Silica Nanospheres for Efficient Flavor Ester Production

Enzymatic synthesis of flavor esters is widely used in the food and flavor industries, but challenges remain in improving the catalytic efficiency and stability of biocatalysts. This study evaluates the performance of a novel biocatalyst, CALB@DMSN-C8, formed by immobilizing Candida antarctica lipase B (CALB) on hydrophobic dendritic mesoporous silica nanospheres (DMSN-C8), for synthesizing flavor esters. The CALB@DMSN-C8 catalyst achieves a caproic acid conversion rate of 98.5 ± 0.5% in just 30 min and demonstrates outstanding thermal stability, retaining a high conversion efficiency over 20 reuse cycles. To our knowledge, this study represents the most efficient synthesis of flavor esters, including ethyl valerate, ethyl caproate, ethyl heptanoate, and ethyl caprylate, compared to studies in the existing literature. Analysis of aroma characteristics and molecular docking simulations revealed the typical flavor profiles and synthesis mechanisms of various mellow esters. This study develops an innovative strategy by using self-made immobilized lipases to catalyze the production of flavor esters with potential applications in food and cosmetics.

A comprehensive review of lipase-catalyzed acidolysis as a method for producing structured glycerides

The production of structured lipids is a current trend in food technology in order to enhance the properties of fats and oils. Lipases have been utilized in many instances for this purpose, in most examples in an immobilized form. In this review, after discussing the different strategies to produce artificial lipids using lipases (esterification, transesterification, interesterification), we have focused on acidolysis. The reaction commences with hydrolysis at one position of the triglyceride molecule and is followed by the esterification between the released hydroxyl group and the target fatty acid (although other carboxylic acids can be used, such as phenolic acid derivatives). This means that water plays a double role, as substrate in the first step and as an undesired by-product in the second one. Therefore, the control of water activity becomes critical in these reactions. This review discusses the advantages, possibilities and drawbacks of this strategy to produce tailor-made designed lipids, summarizing many of the papers related to this strategy. The summarized results show the complexity of this reaction that can make the understanding and reproducibility of the reactions complex if there are no strict controls of all parameters determining the final yields.

Vinyl sulfone-amino-alkyl supports: heterofunctional matrixes to prevent enzyme release and stabilize lipases via covalent immobilization

New trifunctional supports were prepared (amino-octyl-vinyl sulfone (VS)- and amino-hexyl-VS-agarose) and compared to octyl-VS-agarose. They were utilized to immobilize the lipases A and B from Candida antarctica (CALA and CALB). After incubation to generate some enzyme-support bonds and blocking with different nucleophiles, SDS-PAGE analyses showed that all enzyme molecules become covalently immobilized on the support. In all VS biocatalysts, the blocking reagent presented a great effect in the properties of enzymes. The best blocking agents promoted a significant enzyme stabilization compared to the enzyme stability using the amino-alkyl-agarose supports, higher than that using octyl-VS-agarose supports, although these remained the most stable ones in most cases, as the octyl-biocatalysts were significantly more stable than the enzyme immobilized on amino-alkyl-support. Enzyme activities and specificities could be also greatly tuned by the immobilization in the new trifunctional supports, with enzyme activities in many instances enhancing that of the best non-covalently immobilized enzyme. That way, the results on this paper show that the properties of the enzymes when immobilized on these new trifunctional supports may be significantly tuned by the nature of the acyl chain in the support and the nature of the reagent used to block the reactivity of the remaining VS groups.

Lipase Activation by Poly(Methyl Methacrylate) in Dispersed Solution: Mechanistic Insights by Fluorescence Spectroscopy

We investigated the mechanisms of polymer-lipase interactions that govern the catalytic activity of lipases in the presence of polymers. Using a combination of fluorescence correlation spectroscopy (FCS), activity analysis, fluorescence spectroscopy, and computational surface analysis, three model lipases-Thermomyces lanuginosus lipase (TLL), Candida antarctica lipase B (CalB), and Bacillus subtilis lipase A (BSLA), with different degrees of hydrophobic active site exposure were studied. Low-molecular-weight poly(methyl methacrylate) (PMMA), synthesized via ARGET ATRP, was employed to study the effect of unstructured polymers in dispersed solution on lipase activity. PMMA significantly enhanced TLL and BSLA hydrolytic activity, while no CalB activation was observed. FCS analysis indicated that this activation was facilitated by polymer lipase binding, a phenomenon observed with TLL and BSLA but not with CalB. Computational analysis further revealed that the surface properties of the lipases were critical for the lipases' susceptibility to activation by PMMA. Although CalB exhibited the largest total hydrophobic surface area, its homogeneous distribution prevented activation, whereas strong, localized hydrophobic interactions allowed PMMA to bind and activate TLL and BSLA. Supported by the quantitative correlation between elevated 8-anilino-1-naphthalenesulfonic acid (ANS) fluorescence in the presence of PMMA and lipase activity, the activation was attributed to locally increased hydrophobicity of the lipases upon polymer binding. These findings provide critical insights into the role of polymer interactions in lipase activation and stabilization, highlighting the potential for designing tailored polymer carriers to optimize enzyme performance in industrial and biotechnological applications.

Enzyme loading in the support and medium composition during immobilization alter activity, specificity and stability of octyl agarose-immobilized Eversa Transform

Eversa Transform (ETL) was immobilized on octyl agarose beads at two different enzymes loadings (1 mg/g and 15 mg/g) under 18 different conditions, including different pH values, buffers, additives (different solvents, Ca2+, NaCl). Their activity was analyzed at pH 5 and 7 with p-nitrophenyl butyrate and at pH 5 with triacetin, determining also its stability at pH 5 and 7 (in different media). Ca2+ stabilized ETL biocatalysts while phosphate destabilized them. The overloaded biocatalysts were generally less stable and with a lower specific activity than the lowly loaded biocatalyst. Results show that enzyme activity (even by a 3 fold factor) and stability of the immobilized enzyme may be tailored by controlling the immobilization conditions, but the effects of the immobilization conditions on activity depend on the substrate and conditions of activity determination, the effects on stability depend on the inactivation conditions. Moreover, the enzyme loading of the biocatalysts defines the effects of the immobilization conditions, and there are clear interactions between immobilization conditions (e.g., immobilization pH determines the effect of the presence of NaCl). These suggest that the extrapolation of the results obtained with one substrate under one condition to other conditions can lead to wrong decisions.

Interplay of Monosaccharide Configurations on the Deacetylation with Candida antarctica Lipase-B

Configurational differences in monosaccharides determine the products and selectivity of the transesterification reaction with Candida antarctica lipase-B (CAL-B). The β-anomers of peresterified pyranose monosaccharides tend to yield anomeric deprotection products, while the α-anomers preferentially react at the sixth or fourth position. CAL-B differentiates between enantiomers, either reacting more rapidly with d-enantiomers of monosaccharides or having a different selectivity based on the enantiomer. Pivaloylated and benzoylated saccharides are the limits of the CAL-B transesterification reaction, while lower boiling point alcohols such as MeOH and EtOH can replace n-BuOH as the nucleophilic reagent. Finally, CAL-B can be successfully recycled in both long and short reaction time reactions.

AlphaFold 3.0 Prediction Reveals Stronger Interaction between Oleic Acid and Colipase than Palmitic Acid

The interaction between colipase and lipase is known to be crucial for lipid digestion, but the roles of other factors remain unclear. This study explores the dynamics of pancreatic lipase hydrolysis facilitated by colipase, with a focus on the regulatory roles of fatty acids and calcium ions. Using computational modeling, including insights from AlphaFold 3.0, we elucidate the structural interactions essential for hydrolysis activity. The prediction highlights the significant role of calcium ions in altering the interaction between fatty acids and the lipase-colipase complex, thereby changing catalytic efficiency. We further demonstrate that slower hydrolysis rates are associated with a stronger binding affinity between colipase and oleic acid, as well as the occupation of the lipase catalytic pocket by oleic acid in the presence of calcium ions. The AlphaFold predictions provide a robust framework for experimental validation and potential applications. These findings offer deeper insights into dietary lipid digestion and highlight potential avenues for interventions addressing lipid digestion in malnutrition.

Harnessing bio and (Photo)catalysts for microplastics degradation and remediation in soil environment

Soil pollution by microplastics (MPs) is an escalating environmental crisis with far-reaching consequences. However, current research on the degradation and/or remediation of MPs has mainly focused on water-simulated environments, with little attention given to soil MPs. Therefore, the review explores such terrestrial territory, exploring the potential of biodegradation and novel photocatalytic technologies for MPs degradation/remediation in soil. This review comprehensively investigates the potential of biological and photocatalytic approaches for soil MPs degradation and remediation. A temporal analysis of research from 2004 to 2024 highlights the increasing focus on this critical issue. The review explores the biocatalytic roles of diverse enzymes, including cutinase, PETase, MHETase, hydrolase, lipase, laccase, lignin peroxidase, and Mn-peroxidase, in MPs degradation. Strategies for enzyme engineering, such as protein engineering and immobilization, are explored to enhance catalytic efficiency. The potential for developing enzyme consortia for optimized MP degradation is also discussed. Photocatalytic remediation using TiO2, ZnO, clay, hydrogel, and other photocatalysts is examined, emphasizing their mechanisms and effectiveness. Computational modeling is proposed to deepen understanding of soil MPs-catalyst interactions, primarily aiming to develop novel catalysts tailored for soil environments for environmental safety and sustainable restoration. A comparative analysis of biological and photocatalytic approaches evaluates their environmental implications and the potential for synergistic combinations, with emphasis on soil quality protection, restoration and impact on soil ecosystems. Hence, this review accentuates the urgent need for innovative solutions to address MPs pollution in soil and provides a foundational understanding of the current knowledge gaps, as well as paves the way for future research and development.

Structures of BlEst2 from Bacillus licheniformis in its propeptide and mature forms reveal autoinhibitory effects of the C-terminal domain

Carboxylesterases comprise a major class of α/β-fold hydrolases responsible for the cleavage and formation of ester bonds. Found ubiquitously in nature, these enzymes are crucial for the metabolism of both endogenous and exogenous carboxyl esters in animals, plants and microorganisms. Beyond their essential physiological roles, carboxylesterases stand out as one of the important classes of biocatalysts for biotechnology. BlEst2, an enzyme previously classified as Bacillus licheniformis esterase, remains largely uncharacterized. In the present study, we elucidate the structural biology, molecular dynamics and biochemical features of BlEst2. Our findings reveal a canonical α/β-hydrolase fold similar to the ESTHER block L of lipases, further augmented by two additional accessory C-terminal domains. Notably, the catalytic domain demonstrates two insertions, which occupy conserved locations in α/β-hydrolase proteins and commonly form the lid domain in lipase structures. Intriguingly, our in vitro cleavage of C-terminal domains revealed the structure of the active form of BlEst2. Upon activation, BlEst2 showed a markedly elevated hydrolytic activity. This observation implies that the intramolecular C-terminal domain serves as a regulatory intramolecular inhibitor. Interestingly, despite exhibiting esterase-like activity, BlEst2 structural characteristics align more closely with lipases. This suggests that BlEst2 could potentially represent a previously unrecognized subgroup within the realm of carboxyl ester hydrolases.

In-situ stabilized lipase in calcium carbonate microparticles for activation in solvent-free transesterification for biodiesel production

Biodiesel serves as a crucial biofuel alternative to petroleum-based diesel fuels, achieved through enzymatic transesterification of oil substrates. This study aims to investigate stabilized lipase (LP) within calcium carbonate (CaCO3) microparticles as a catalyst for solvent-free transesterification in biodiesel synthesis. The specific hydrolysis activity of the in-situ immobilized LP was 66% of that of free LP. However, the specific transesterification activity of immobilized LP in the solvent-free phase for biodiesel production was 2.29 times higher than that of free LP. These results suggest that the interfacial activation of LP molecules is facilitated by the inorganic CaCO3 environment. The immobilized LP demonstrated higher biodiesel production levels with superior stability compared to free LP, particularly regarding methanol molar ratio and temperature. To the best of our knowledge, there are no previous reports on the in-situ immobilization of LP in a CaCO3 carrier without any crosslinker as an interfacial-activated biocatalyst for biodiesel production.

Advanced glycation end-product crosslinking activates a type VI secretion system phospholipase effector protein

Advanced glycation end-products (AGE) are a pervasive form of protein damage implicated in the pathogenesis of neurodegenerative disease, atherosclerosis and diabetes mellitus. Glycation is typically mediated by reactive dicarbonyl compounds that accumulate in all cells as toxic byproducts of glucose metabolism. Here, we show that AGE crosslinking is harnessed to activate an antibacterial phospholipase effector protein deployed by the type VI secretion system of Enterobacter cloacae. Endogenous methylglyoxal reacts with a specific arginine-lysine pair to tether the N- and C-terminal α-helices of the phospholipase domain. Substitutions at these positions abrogate both crosslinking and toxic phospholipase activity, but in vitro enzyme function can be restored with an engineered disulfide that covalently links the N- and C-termini. Thus, AGE crosslinking serves as a bona fide post-translation modification to stabilize phospholipase structure. Given the ubiquity of methylglyoxal in prokaryotic and eukaryotic cells, these findings suggest that glycation may be exploited more generally to stabilize other proteins. This alternative strategy to fortify tertiary structure could be particularly advantageous in the cytoplasm, where redox potentials preclude disulfide bond formation.

Substrate specificity of commercial lipases activated by a hydration-aggregation pretreatment in anhydrous esterification reactions

Substrate specificity in non-aqueous esterification catalyzed by commercial lipases activated by hydration-aggregation pretreatment was investigated. Four microbial lipases from Rhizopus japonicus, Burkholderia cepacia, Rhizomucor miehei, and Candida antarctica (fraction B) were used to study the effect of the carbon chain length of saturated fatty acid substrates on the esterification activity with methanol in n-hexane. Hydration-aggregation pretreatment had an activation effect on all lipases used, and different chain length dependencies of esterification activity for lipases from different origins were demonstrated. The effects of various acidic substrates with different degrees of unsaturation, aromatic rings, and alcohol substrates with different carbon chain lengths on esterification activity were examined using R. japonicus lipase, which demonstrated the most remarkable activity enhancement after hydration-aggregation pretreatment. Furthermore, in the esterification of myristic acid with methanol catalyzed by the hydrated-aggregated R. japonicus lipase, maximum reaction rate (5.43 × 10-5 mmol/(mg-biocat min)) and Michaelis constants for each substrate (48.5 mM for myristic acid, 24.7 mM for methanol) were determined by kinetic analysis based on the two-substrate Michaelis-Menten model.

Molecular simulations guide immobilization of lipase on nest-like ZIFs with regulatable hydrophilic/hydrophobic surface

The catalytic performance of immobilized lipase is greatly influenced by functional support, which attracts growing interest for designing supports to achieve their promotive catalytic activity. Many lipases bind strongly to hydrophobic surfaces where they undergo interfacial activation. Herein, the behavioral differences of lipases with distinct lid structures on interfaces of varying hydrophobicity levels were firstly investigated by molecular simulations. It was found that a reasonable hydrophilic/hydrophobic surface could facilitate the lipase to undergo interfacial activation. Building on these findings, a novel "nest"-like superhydrophobic ZIFs (ZIFN) composed of hydrophobic ligands was prepared for the first time and used to immobilize lipase from Aspergillus oryzae (AOL@ZIFN). The AOL@ZIFN exhibited 2.0-folds higher activity than free lipase in the hydrolysis of p-Nitrophenyl palmitate (p-NPP). Especially, the modification of superhydrophobic ZIFN with an appropriate amount of hydrophilic tannic acid can significantly improve the activity of the immobilized lipase (AOL@ZIFN-TA). The AOL@ZIFN-TA exhibited 30-folds higher activity than free lipase, and still maintained 82% of its initial activity after 5 consecutive cycles, indicating good reusability. These results demonstrated that nanomaterials with rational arrangement of the hydrophilic/hydrophobic surface could facilitate the lipase to undergo interfacial activation and improve its activity, displaying the potential of the extensive application.

Oleic Acid and Linoleic Acid Enhances the Biocontrol Potential of Metarhizium rileyi

Metarhizium rileyi is a wide spread insect fungi with a good biocontrol potentiality to various pests, particularly noctuid insects. However, it is characterized by its slow growth, its sensitivity to abiotic stress, and the slow speed of kill to pests, which hinder its use compared with other entomopathogenic fungi. In this study, the responses of M. rileyi to eight types of lipids were observed; among the lipids, oleic acid and linoleic acid significantly promoted the growth and development of M. rileyi and enhanced its stress tolerances and virulence. An additional mechanistic study demonstrated that exogenous oleic acid and linoleic acid significantly improved the conidial germination, appressorium formation, cuticle degradation, and cuticle infection, which appear to be largely dependent on the up-regulation of gene expression in growth, development, protective, and cuticle-degrading enzymes. In conclusion, exogenous oleic acid and linoleic acid enhanced the stress tolerances and virulence of M. rileyi via protecting conidial germination and promoting cuticle infection. These results provide new insights for the biopesticide development of M. rileyi.

An Alternative Approach to Plastic Recycling: Fabrication and Characterization of rPET/CA Nanofiber Carriers to Enhance Porcine Pancreatic Lipase Stability Properties

In response to the increasing demand for sustainable technologies, this study presents a novel approach to plastic recycling. In this study, a method was presented to produce nanofiber carriers by electrospinning using recycled poly(ethylene terephthalate) (rPET) obtained from wastewater bottles and cellulose acetate (CA). These carriers serve as a platform for immobilized porcine pancreatic lipase (PPL), aiming to enhance its stability. The production parameters for the rPET/CA nanofibers were found to be an rPET concentration of 15% (v/v), a CA concentration of 6% (v/v), an electrical voltage of 13 kV, a needle-collector distance of 18 cm, and an injection speed of 0.1 mL/h. The nanofiber structure and morphology were assessed by using attenuated total reflectance-infrared Fourier transform infrared (ATR-FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) analyses. Then, PPL was immobilized onto the nanofibers through adsorption and cross-linking methods. The optimum temperature for free PPL was determined to be 30 °C, and the optimum temperature for PPL immobilized on rPET/CA was determined to be 40 °C. It was observed that, especially under acidic conditions, after the immobilization process, PPL immobilized rPET/CA nanofibers became more resistant to pH changes than free PLL. Furthermore, the immobilized PPL exhibited improved pH stability, reusability, and thermal stability compared to its free counterpart. This innovative approach not only contributes to plastic waste reduction but also opens new avenues for enzyme immobilization with potential applications in biocatalysis and wastewater treatment.

A Whole-Process Visible Strategy for the Preparation of Rhizomucor miehei Lipase with Escherichia coli Secretion Expression System and the Immobilization

BACKGROUND

Rhizomucor miehei (RM) lipase is a regioselective lipase widely used in food, pharmaceutical and biofuel industries. However, the high cost and low purity of the commercial RM lipase limit its industrial applications. Therefore, it is necessary to develop cost-effective strategies for large-scale preparation of this lipase. The present study explored the high-level expression of RM lipase using superfolder green fluorescent protein (sfGFP)-mediated Escherichia coli secretion system.

RESULTS

The sfGFP(-15) mutant was fused to the C-terminus of RM lipase to mediate its secretion expression. The yield of the fusion protein reached approximately 5.1 g/L with high-density fermentation in 5-L fermentors. Unlike conventional secretion expression methods, only a small portion of the target protein was secreted into the cell culture while majority of the fusion protein was still remained in the cytoplasm. However, in contrast to intracellular expression, the target protein in the cytoplasm could be transported efficiently to the supernatant through a simple washing step with equal volume of phosphate saline (PBS), without causing cell disruption. Hence, the approach facilitated the downstream purification step of the recombinant RM lipase. Moreover, contamination or decline of the engineered strain and degradation or deactivation of the target enzyme can be detected efficiently because they exhibited bright green fluorescence. Next, the target protein was immobilized with anion-exchange and macropore resins. Diethylaminoethyl sepharose (DEAE), a weak-basic anion-exchange resin, exhibited the highest bind capacity but inhibited the activity of RM lipase dramatically. On the contrary, RM lipase fixed with macropore resin D101 demonstrated the highest specific activity. Although immobilization with D101 didn't improve the activity of the enzyme, the thermostability of the immobilized enzyme elevated significantly. The immobilized RM lipase retained approximately 90% of its activity after 3-h incubation at 80 °C. Therefore, D101 was chosen as the supporting material of the target protein.

CONCLUSION

The present study established a highly efficient strategy for large-scale preparation of RM lipase. This innovative technique not only provides high-purity RM lipase at a low cost but also has great potential as a platform for the preparation of lipases in the future.

Enzymatic interfacial conversion of acylglycerols in Pickering emulsions stabilized by hydrogel microparticles

HYPOTHESIS

A critical challenge in the enzymatic conversion of acylglycerols is the limited exposure of the enzyme dissolved in the aqueous solution to the hydrophobic substrate in the oil phase. Positioning the enzyme in a microenvironment with balanced hydrophobicity and hydrophilicity in Pickering emulsion will facilitate the acylglycerol-catalyzing reactions at the interface between the oil and liquid phases.

EXPERIMENTS

In this work, to overcome the challenge of biphasic catalysis, we report a method to immobilize enzymes in polyethylene glycol (PEG)-based hydrogel microparticles (HMPs) at the interface between the oil and water phases in Pickering emulsion to promote the enzymatic conversion of acylglycerols.

FINDINGS

3 wt% of HMPs can stabilize the oil-in-water Pickering emulsion for at least 14 days and increase the viscosity of emulsions. Lipase-HMP conjugates showed significantly higher hydrolytic activity in Pickering emulsion; HMP-immobilized lipase SMG1 showed an activity about three times that of free lipase SMG1. Co-immobilization of a lipase and a fatty acid photodecarboxylase from Chlorella variabilis (CvFAP) in Pickering emulsion enables light-driven cascade conversion of triacylglycerols to hydrocarbons, transforming waste oil to renewable biofuels in a green and sustainable approach. HMPs stabilize the Pickering emulsion and promote interfacial biocatalysis in converting acylglycerols to renewable biofuels.

Enhanced triolein and ethyl ferulate interesterification performance by CRL-AuNPs

This study established a Candida rugosa lipase (CRL) system to catalyze triolein and ethyl ferulate interesterification. The products were identified, and the binding mode between the substrates and CRL was predicted through molecular docking. Three methods for preparing CRL-AuNPs were proposed and characterized. It was found that the addition of 40 mL of 15 nm gold nanoparticles increased the CRL activity from 3.05 U/mg to 4.75 U/mg, but the hybridization efficiency was only 32.7 %. By using 4 mL of 0.1 mg/mL chloroauric acid, the hybridization efficiency was improved to 50.7 %, but the enzyme activity was sharply decreased. However, when the molar ratio of Mb to HAuCl4 was 0.2, the hybridization efficiency increased to 71.8 %, and the CRL activity was also enhanced to 5.98 U/mg. Under optimal conditions, the enzyme activity of CRL-AuNPs③ was maintained at 95 % after 6 repetitions and 85.6 % after 30 days at room temperature.

Characterization of a recombinant Aspergillus niger GZUF36 lipase immobilized by ionic liquid modification strategy

Enzyme immobilized on magnetic nanomaterials is a promising biocatalyst with efficient recovery under applied magnets. In this study, a recombinant extracellular lipase from Aspergillus niger GZUF36 (PEXANL1) expressed in Pichia pastoris GS115 was immobilized on ionic liquid-modified magnetic nano ferric oxide (Fe3O4@SiO2@ILs) via electrostatic and hydrophobic interaction. The morphology, structure, and properties of Fe3O4@SiO2@ILs and immobilized PEXANL1 were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, x-ray diffraction, vibration sample magnetometer, and zeta potential analysis. Under optimized conditions, the immobilization efficiency and activity recovery of immobilized PEXANL1 were 52 ± 2% and 122 ± 2%, respectively. The enzymatic properties of immobilized PEXANL1 were also investigated. The results showed that immobilized PEXANL1 achieved the maximum activity at pH 5.0 and 45 °C, and the lipolytic activity of immobilized PEXANL1 was more than twice that of PEXANL1. Compared to PEXANL1, immobilized PEXANL1 exhibited enhanced tolerance to temperature, metal ions, surfactants, and organic solvents. The operation stability experiments revealed that immobilized PEXANL1 maintained 86 ± 3% of its activity after 6 reaction cycles. The enhanced catalytic performance in enzyme immobilization on Fe3O4@SiO2@ILs made nanobiocatalysts a compelling choice for bio-industrial applications. Furthermore, Fe3O4@SiO2@ILs could also benefit various industrial enzymes and their practical uses. KEY POINTS: • Immobilized PEXANL1 was confirmed by SEM, FT-IR, and XRD. • The specific activity of immobilized PEXANL1 was more than twice that of PEXANL1. • Immobilized PEXANL1 had improved properties with good operational stability.

The effects of the chemical modification on immobilized lipase features are affected by the enzyme crowding in the support

In this article, we have analyzed the interactions between enzyme crowding on a given support and its chemical modification (ethylenediamine modification via the carbodiimide route and picryl sulfonic (TNBS) modification of the primary amino groups) on the enzyme activity and stability. Lipase from Thermomyces lanuginosus (TLL) and lipase B from Candida antarctica (CALB) were immobilized on octyl-agarose beads at two very different enzyme loadings, one of them exceeding the capacity of the support, one well under this capacity. Chemical modifications of the highly loaded and lowly loaded biocatalysts gave very different results in terms of activity and stability, which could increase or decrease enzyme activity depending on the enzyme support loading. For example, both lowly loaded biocatalysts increased their activity after modification while the effect was the opposite for the highly loaded biocatalysts. Additionally, the modification with TNBS of highly loaded CALB biocatalyst increased its stability while decrease the activity.

Structure elucidation of Staphylococcus capitis lipase. Molecular dynamics simulations to investigate the effects of calcium and zinc ions on the structural stability

Cold-adapted and organic solvent tolerant lipases have significant potential in a wide range of synthetic reactions in industry. But there are no sufficient studies on how these enzymes interacts with their substrates. Herein, the predicted structure and function of the Staphylococcus capitis lipase (SCL) are studied. Given the high amino acid sequence homology with the Staphylococcus simulans lipase (SSL), 3D structure models of closed and open forms of the S. capitis lipase were built using the structure of SSL as template. The models suggested the presence of a main lid and a second lid that may act with the former as a double door to control the access to the active site. The SCL models also allowed us to identify key residues involved in binding substrates, calcium or zinc ions. By following this model and utilizing molecular dynamics (MD) simulations, the stability of the S. capitis lipase at low temperatures could be explained in the presence and in the absence of calcium and zinc. Due to its thermolability, the SCL is extremely valuable for different biotechnological applications in a wide variety of industries from molecular biology to detergency to food and beverage preparation.Communicated by Ramaswamy H. Sarma.

From nature to industry: Harnessing enzymes for biocatalysis

Biocatalysis harnesses enzymes to make valuable products. This green technology is used in countless applications from bench scale to industrial production and allows practitioners to access complex organic molecules, often with fewer synthetic steps and reduced waste. The last decade has seen an explosion in the development of experimental and computational tools to tailor enzymatic properties, equipping enzyme engineers with the ability to create biocatalysts that perform reactions not present in nature. By using (chemo)-enzymatic synthesis routes or orchestrating intricate enzyme cascades, scientists can synthesize elaborate targets ranging from DNA and complex pharmaceuticals to starch made in vitro from CO2-derived methanol. In addition, new chemistries have emerged through the combination of biocatalysis with transition metal catalysis, photocatalysis, and electrocatalysis. This review highlights recent key developments, identifies current limitations, and provides a future prospect for this rapidly developing technology.

Biocatalytic production of biolubricants: Strategies, problems and future trends

The increasing worries by the inadequate use of energy and the preservation of nature are promoting an increasing interest in the production of biolubricants. After discussing the necessity of producing biolubricants, this review focuses on the production of these interesting molecules through the use of lipases, discussing the different possibilities (esterification of free fatty acids, hydroesterification or transesterification of oils and fats, transesterification of biodiesel with more adequate alcohols, estolides production, modification of fatty acids). The utilization of discarded substrates has special interest due to the double positive ecological impact (e.g., oil distillated, overused oils). Pros and cons of all these possibilities, together with general considerations to optimize the different processes will be outlined. Some possibilities to overcome some of the problems detected in the production of these interesting compounds will be also discussed.

Enhancing the Hydrolytic Activity of a Lipase towards Larger Triglycerides through Lid Domain Engineering

Lipases have valuable potential for industrial use, particularly those mostly active against water-insoluble substrates, such as triglycerides composed of long-carbon chain fatty acids. However, in most cases, engineered variants often need to be constructed to achieve optimal performance for such substrates. Protein engineering techniques have been reported as strategies for improving lipase characteristics by introducing specific mutations in the cap domain of esterases or in the lid domain of lipases or through lid domain swapping. Here, we improved the lipase activity of a lipase (WP_075743487.1, or LipMRD) retrieved from the Marine Metagenomics MarRef Database and assigned to the Actinoalloteichus genus. The improvement was achieved through site-directed mutagenesis and by substituting its lid domain (FRGTEITQIKDWLTDA) with that of Rhizopus delemar lipase (previously R. oryzae; UniProt accession number, I1BGQ3) (FRGTNSFRSAITDIVF). The results demonstrated that the redesigned mutants gain activity against bulkier triglycerides, such as glyceryl tridecanoate and tridodecanoate, olive oil, coconut oil, and palm oil. Residue W89 (LipMRD numbering) appears to be key to the increase in lipase activity, an increase that was also achieved with lid swapping. This study reinforces the importance of the lid domains and their amino acid compositions in determining the substrate specificity of lipases, but the generalization of the lid domain swapping between lipases or the introduction of specific mutations in the lid domain to improve lipase activity may require further investigation.

Glutaraldehyde modification of lipases immobilized on octyl agarose beads: Roles of the support enzyme loading and chemical amination of the enzyme on the final enzyme features

Lipase B from Candida antarctica (CALB) and lipase from Thermomyces lanuginosus (TLL) have been immobilized on octyl agarose at low loading and at a loading exceeding the maximum support capacity. Then, the enzymes have been treated with glutaraldehyde and inactivated at pH 7.0 in Tris-HCl, sodium phosphate and HEPES, giving different stabilities. Stabilization (depending on the buffer) of the highly loaded biocatalysts was found, very likely as a consequence of the detected intermolecular crosslinkings. This did not occur for the lowly loaded biocatalysts. Next, the enzymes were chemically aminated and then treated with glutaraldehyde. In the case of TLL, the intramolecular crosslinkings (visible by the apparent reduction of the protein size) increased enzyme stability of the lowly loaded biocatalysts, an effect that was further increased for the highly loaded biocatalysts due to intermolecular crosslinkings. Using CALB, the intramolecular crosslinkings were less intense, and the stabilization was lower, even though the intermolecular crosslinkings were quite intense for the highly loaded biocatalyst. The stabilization detected depended on the inactivation buffer. The interactions between enzyme loading and inactivating buffer on the effects of the chemical modifications suggest that the modification and inactivation studies must be performed under the target biocatalysts and conditions.

Interfacial adsorption behavior of the Aspergillus oryzae lipase-chitosan complex and stability evaluation of the resultant Pickering emulsion

To prompt the application of the chitosan (CS)-Aspergillus oryzae lipase (AOL) complex in the construction of novel biphasic catalysis medium, its Pickering emulsion stabilization ability as well as adsorption behavior in the oil-water interface were investigated and the stability of resultant emulsion was evaluated. The results indicated that the CS-AOL complex assembled in mass ratio 1:5 was an effective Pickering stabilizer and up to 90 % AOL could be retained in the emulsion interface. Quartz crystal microbalance with dissipation monitoring suggested that the CS-AOL complex spontaneously absorbed to oil-water interface; absorption dynamics analysis revealed that the adsorption was driven by diffusion accompanied by rapid structural rearrangement; while interfacial dilatational rheology demonstrated the formation of an elastic film in the oil-water interface. The Pickering emulsions were pseudoplastic and that in oil fraction 0.6 exhibited the elastic behavior in contrast to the viscous behavior in oil fractions 0.2 and 0.4. The Pickering emulsion exhibited excellent stability against storage for up to 28 d, pHs 2.0-12.0, heating at 25-90 °C, and up to 500 mmol/L NaCl, and the corresponding interfacial AOL retentions exceeded 80 % during exposure to these conditions. Hence, the CS-AOL complex could be used as a stabilizer to construct Pickering emulsion-based biphasic catalysis systems.

Single-Particle Tracking of Thermomyces lanuginosus Lipase Reveals How Mutations in the Lid Region Remodel Its Diffusion

The function of most lipases is controlled by the lid, which undergoes conformational changes at a water–lipid interface to expose the active site, thus activating catalysis. Understanding how lid mutations affect lipases’ function is important for designing improved variants. Lipases’ function has been found to correlate with their diffusion on the substrate surface. Here, we used single-particle tracking (SPT), a powerful tool for deciphering enzymes’ diffusional behavior, to study Thermomyces lanuginosus lipase (TLL) variants with different lid structures in a laundry-like application condition. Thousands of parallelized recorded trajectories and hidden Markov modeling (HMM) analysis allowed us to extract three interconverting diffusional states and quantify their abundance, microscopic transition rates, and the energy barriers for sampling them. Combining those findings with ensemble measurements, we determined that the overall activity variation in the application condition is dependent on surface binding and lipase mobility when bound. Specifically, the L4 variant with a TLL-like lid and wild-type (WT) TLL displayed similar ensemble activity, but WT bound stronger to the surface than L4, while L4 had a higher diffusion coefficient and thus activity when bound to the surface. These mechanistic elements can only be de-convoluted by our combined assays. Our findings offer fresh perspectives on the development of the next iteration of enzyme-based detergent.

Immobilization of Lipase B from Candida antarctica in Octyl-Vinyl Sulfone Agarose: Effect of the Enzyme-Support Interactions on Enzyme Activity, Specificity, Structure and Inactivation Pathway

Lipase B from Candida antarctica was immobilized on heterofunctional support octyl agarose activated with vinyl sulfone to prevent enzyme release under drastic conditions. Covalent attachment was established, but the blocking step using hexylamine, ethylenediamine or the amino acids glycine (Gly) and aspartic acid (Asp) altered the results. The activities were lower than those observed using the octyl biocatalyst, except when using ethylenediamine as blocking reagent and p-nitrophenol butyrate (pNPB) as substrate. The enzyme stability increased using these new biocatalysts at pH 7 and 9 using all blocking agents (much more significantly at pH 9), while it decreased at pH 5 except when using Gly as blocking agent. The stress inactivation of the biocatalysts decreased the enzyme activity versus three different substrates (pNPB, S-methyl mandelate and triacetin) in a relatively similar fashion. The tryptophane (Trp) fluorescence spectra were different for the biocatalysts, suggesting different enzyme conformations. However, the fluorescence spectra changes during the inactivation were not too different except for the biocatalyst blocked with Asp, suggesting that, except for this biocatalyst, the inactivation pathways may not be so different.

Lipase and Its Unique Selectivity: A Mini-Review

Contrary to other solid catalysts, enzymes facilitate more sophisticated chemical reactions because most enzymes specifically interact with substrates and release selective products. Lipases (triacylglycerol hydrolase, EC 3.1.1.3), which can catalyze the cleavage and formation of various acyl compounds, are one of the best examples of enzymes with a unique substrate selectivity. There are already several commercialized lipases that have become important tools for various lipid-related studies, although there is still a need to discover novel lipases with unique substrate selectivity to facilitate more innovative reactions in human applications such as household care, cosmetics, foods, and pharmaceuticals. In this mini-review, we focus on concisely demonstrating not only the general information of lipases but also their substate selectivities: typoselectivity, regioselectivity, and stereoselectivity. We highlight the essential studies on selective lipases in terms of enzymology. Furthermore, we introduce several examples of analysis methodology and experimental requirements to determine each selectivity of lipases. This work would stress the importance of integrating our understanding of lipase chemistry to make further advances in the relevant fields.

2-Arachidonoylglycerol Synthesis: Facile and Handy Enzymatic Method That Allows to Avoid Isomerization

A simple and practical synthesis of 2-arachidonoyl glycerol (2-AG), an endogenous agonist for cannabinoid receptors, based on a two-step enzymatic process and a chemical coupling, was achieved with a good yield and negligible amount of the isomerization product 1-AG. Commercial preparation of immobilized lipase from Mucor miehei (MML) was selected as the most suitable enzyme to catalyze the efficient protection of glycerol using vinyl benzoate as an acyl transfer reagent in tetrahydrofuran. The same enzyme was used to remove the protective groups in positions 1 and 3. Owing to the mild neutral conditions and easy suitability of the method, 2-AG was obtained without any isomerization to the more stable 1-AG and air oxidation of acid chain. The synthetic method proposed here allows us to easily obtain 2-AG from the protected precursor in a one-step reaction without purification requirement.

Opposing effects of MYZUS PERSICAE-INDUCED LIPASE 1 and jasmonic acid influence the outcome of Arabidopsis thaliana-Fusarium graminearum interaction

Fusarium graminearum (Fg) is an important fungal pathogen of small grain cereals that can also infect Arabidopsis thaliana. In Arabidopsis, jasmonic acid (JA) signalling involving JASMONATE RESISTANT 1 (JAR1), which synthesizes JA-isoleucine, a signalling form of JA, promotes susceptibility to Fg. Here we show that Arabidopsis MYZUS PERSICAE-INDUCED LIPASE 1 (MPL1), via its influence on limiting JA accumulation, restricts Fg infection. MPL1 expression was up-regulated in response to Fg infection, and MPL1-OE plants, which overexpress MPL1, exhibited enhanced resistance against Fg. In comparison, disease severity was higher on the mpl1 mutant than the wild type. JA content was lower in MPL1-OE and higher in mpl1 than in the wild type, indicating that MPL1 limits JA accumulation. Pharmacological experiments confirmed the importance of MPL1-determined restriction of JA accumulation on curtailment of Fg infection. Methyl-JA application attenuated the MPL1-OE-conferred resistance, while the JA biosynthesis inhibitor ibuprofen enhanced resistance in mpl1. Also, the JA biosynthesis-defective opr3 mutant was epistatic to mpl1, resulting in enhanced resistance in mpl1 opr3 plants. In comparison, JAR1 was not essential for the mpl1-conferred susceptibility to Fg. Considering that methyl-JA promotes Fg growth in culture, we suggest that in part MPL1 curtails disease by limiting the availability of a plant-derived Fg growth-promoting factor.

Immobilized Lipase in Resolution of Ketoprofen Enantiomers: Examination of Biocatalysts Properties and Process Characterization

In this study, lipase from Aspergillus niger immobilized by physical immobilization by the adsorption interactions and partially interfacial activation and mixed physical immobilization via interfacial activation and ion exchange was used in the kinetic resolution of the ketoprofen racemic mixture. The FTIR spectra of samples after immobilization of enzyme-characteristic signals can be seen, and an increase in particle size diameters upon immobilization is observed, indicating efficient immobilization. The immobilization yield was on the level of 93% and 86% for immobilization unmodified and modified support, respectively, whereas activity recovery reached around 90% for both systems. The highest activity of immobilized biocatalysts was observed at pH 7 and temperature 40 °C and pH 8 and 20 °C for lipase immobilized by physical immobilization by the adsorption interactions and partially interfacial activation and mixed physical immobilization via interfacial activation and ion exchange, respectively. It was also shown that over a wide range of pH (from 7 to 10) and temperature (from 20 to 60 °C) both immobilized lipases retained over 80% of their relative activity, indicating improvement of enzyme stability. The best solvent during kinetic resolution of enantiomers was found to be phosphate buffer at pH 7, which obtained the highest efficiency of racemic ketoprofen methyl ester resolution at the level of over 51%, followed by enantiomeric excess 99.85% in the presence of biocatalyst obtained by physical immobilization by the adsorption interactions and partially interfacial activation.

Lipase immobilization via cross-linked enzyme aggregates: Problems and prospects - A review

In this review we have focused on the preparation of cross-linked enzyme aggregates (CLEAs) from lipases, as these are among the most used enzyme in bioprocesses. This immobilization method is considered very attractive due to preparation simplicity, non-use of supports and the possibility of using crude enzyme extracts. CLEAs provide lipase stabilization under extreme temperature or pH conditions or in the presence of organic solvents, in addition to preventing enzyme leaching in aqueous medium. However, it presents some problems in the preparation and limitations in their use. The problems in preparation refer mainly to the crosslinking step, and may be solved using an aminated feeder. The problems in handling have been tackled designing magnetic-CLEAs or trapping the CLEAs in particles with better mechanical properties, the substrate diffusion problems has been reduced by producing more porous-CLEAs, etc. The enzyme co-immobilization using combi-CLEAs is also a new tendency. Therefore, this review explores the CLEAs methodology aimed at lipase immobilization and its applications.

Progress in enrichment of n-3 polyunsaturated fatty acid: a review

n-3 Polyunsaturated fatty acids (n-3 PUFA) has been widely used in foods, and pharmaceutical products due to its beneficial effects. The content of n-3 PUFA in natural oils is usually low, which decreases its added value. Thus, there is an increasing demand on the market for n-3 PUFA concentrates. This review firstly introduces the differences in bioavailability and oxidative stability between different types of PUFA concentrate (free fatty acid, ethyl ester and acylglycerol), and then provides a comprehensive discussion of different methods for enrichment of lipids with n-3 PUFA including physical-chemical methods and enzymatic methods. Lipases used for catalyzing esterification, transesterification and hydrolysis reactions play an important role in the production of highly enriched various types of n-3 PUFA concentrates. Lipase-catalyzed alcoholysis or hydrolysis reactions are the mostly employed method to prepare high-quality n-3 PUFA of structural acylglycerols. Although many important advantages offered by lipases in enrichment of n-3 PUFA, the high cost of enzyme limits its industrial-scale production. Further research should focus on looking for biological enzymes with extraordinary catalytic ability and clear selectivity. Other novel technologies such as protein engineering and immobilization may be needed to modify lipases to improve its selectivity, catalytic ability and reuse.

Influence of Carboxymethyl Cellulose on the Stability, Rheological Property, and in-vitro Digestion of Soy Protein Isolate (SPI)-Stabilized Rice Bran Oil Emulsion

In this study, carboxymethyl cellulose (CMC) was added to soybean protein isolate (SPI)-stabilized rice bran oil (RBO) emulsion to improve its physicochemical stability and free fatty acid (FFA) release characteristics. RBO emulsions stabilized by SPI and various contents of CMC were prepared and assessed by measuring zeta potential, particle size, transmission, and microstructure, the rheological properties were analyzed by dynamic shear rheometer. In addition, its chemical stability was characterized by a storage experiment, and the FFA release was explored by a simulated gastrointestinal tract (GIT) model. It showed that the negative charge of the droplets of RBO emulsion was increased with increasing CMC content. The decrease in transmission of SPI-stabilized RBO emulsion with increasing CMC content was due to the droplets not being free to move by the special network interaction and an increase in the viscosity. According to the determination of the reactive substances of lipid hydroperoxide and thiobarbituric acid during 30 days storage at 37°C, the chemical stability of the emulsion added with CMC was enhanced compared with the SPI-stabilized RBO emulsion. In-vitro digestion studies not only evaluated the structural changes of RBO emulsions at different stages, but also found that RBO emulsion with CMC showed a higher level of free fatty acids release in comparison with that without CMC. It indicated that the utilization of CMC can improve the bioavailability of RBO emulsions.

Two Extracellular Poly(ε-caprolactone)-Degrading Enzymes From Pseudomonas hydrolytica sp. DSWY01T: Purification, Characterization, and Gene Analysis

Poly(ε-caprolactone) (PCL) is an artificial polyester with commercially promising application. In this study, two novel PCL-degrading enzymes named PCLase I and PCLase II were purified to homogeneity from the culture supernatant of an effective polyester-degrading bacterium, Pseudomonas hydrolytica sp. DSWY01^T. The molecular masses of PCLase I and PCLase II were determined to be 27.5 and 30.0 kDa, respectively. The optimum temperatures for the enzyme activities were 50 and 40°C, and the optimum pH values were 9.0 and 10.0, respectively. The two enzymes exhibited different physical and chemical properties, but both enzymes could degrade PCL substrates into monomers and oligomers. Weight loss detection and scanning electron microscopy revealed that PCLase I had more effective degradation ability than PCLase II. The genes of the two enzymes were cloned on the basis of the peptide fingerprint analysis results. The sequence analysis and substrate specificity analysis results showed that PCLase I and PCLase II were cutinase and lipase, respectively. Interface activation experiment also confirmed this conclusion. Structural analysis and modeling were further performed to obtain possible insights on the mechanism.

Coimmobilization of lipases exhibiting three very different stability ranges. Reuse of the active enzymes and selective discarding of the inactivated ones

Lipase B from Candida antarctica (CALB) and lipases from Candida rugosa (CRL) and Rhizomucor miehei (RML) have been coimmobilized on octyl and octyl-Asp agarose beads. CALB was much more stable than CRL, that was significantly more stable than RML. This forces the user to discard immobilized CALB and CRL when only RML has been inactivated, or immobilized CALB when CRL have been inactivated. To solve this problem, a new strategy has been proposed using three different immobilization protocols. CALB was covalently immobilized on octyl-vinyl sulfone agarose and blocked with Asp. Then, CRL was immobilized via interfacial activation. After coating both immobilized enzymes with polyethylenimine, RML could be immobilized via ion exchange. That way, by incubating in ammonium sulfate solutions, inactivated RML could be released enabling the reuse of coimmobilized CRL and CALB to build a new combi-lipase. Incubating in triton and ammonium sulfate solutions, it was possible to release inactivated CRL and RML, enabling the reuse of immobilized CALB when CRL was inactivated. These cycles could be repeated for 3 full cycles, maintaining the activity of the active and immobilized enzymes.

Lipase-catalyzed esterification in water enabled by nanomicelles. Applications to 1-pot multi-step sequences

Esterification in an aqueous micellar medium is catalyzed by a commercially available lipase in the absence of any co-factors. The presence of only 2 wt% designer surfactant, TPGS-750-M, assists in a 100% selective enzymatic process in which only primary alcohols participate (in a 1 : 1 ratio with carboxylic acid). An unexpected finding is also disclosed where the simple additive, PhCF3 (1 equiv. vs. substrate), appears to significantly extend the scope of usable acid/alcohol combinations. Taken together, several chemo- and bio-catalyzed 1-pot, multi-step reactions can now be performed in water.

Stabilization of enzymes via immobilization: Multipoint covalent attachment and other stabilization strategies

The use of enzymes in industrial processes requires the improvement of their features in many instances. Enzyme immobilization, a requirement to facilitate the recovery and reuse of these water-soluble catalysts, is one of the tools that researchers may utilize to improve many of their properties. This review is focused on how enzyme immobilization may improve enzyme stability. Starting from the stabilization effects that an enzyme may experience by the mere fact of being inside a solid particle, we detail other possibilities to stabilize enzymes: generation of favorable enzyme environments, prevention of enzyme subunit dissociation in multimeric enzymes, generation of more stable enzyme conformations, or enzyme rigidification via multipoint covalent attachment. In this last point, we will discuss the features of an "ideal" immobilization protocol to maximize the intensity of the enzyme-support interactions. The most interesting active groups in the support (glutaraldehyde, epoxide, glyoxyl and vinyl sulfone) will be also presented, discussing their main properties and uses. Some instances in which the number of enzyme-support bonds is not directly related to a higher stabilization will be also presented. Finally, the possibility of coupling site-directed mutagenesis or chemical modification to get a more intense multipoint covalent immobilization will be discussed.

Enhanced enzymatic performance of immobilized lipase on metal organic frameworks with superhydrophobic coating for biodiesel production

Inspired by the interfacial catalysis of lipase, Herein, the hydrophobic ZIF-L coated with polydimethylsiloxane (PDMS) were prepared by chemical vapor deposition (CVD) and used to immobilize lipase from Aspergillus oryzae (AOL) for biodiesel production. The results showed that the PDMS coating enhanced the stability of ZIF-8 and ZIF-L in PBS. Immobilization efficiency of AOL on PDMS-modified ZIF-L was 96% under optimized conditions. The resultant immobilized lipase (AOL@PDMS-ZIF-L) exhibited higher activity recovery (430%) than AOL@ZIF-L. Meanwhile, compared with free lipase, the AOL@PDMS-ZIF-L exhibited better storage stability and thermal stability. After 150 days of storage, the free lipase retained only 20% of its original activity of hydrolyzing p-NPP, while the AOL@PDMS-ZIF-L still retained 90% of its original activity. The biodiesel yield catalyzed from soybean oil by free lipase was only 69%, However, the biodiesel yield by AOL@PDMS-ZIF-L reached 94%, and could still be maintained at 85% even after 5 consecutive cycles. It is believed that this convenient and versatile strategy has great promise in the important fields of immobilized lipase on MOF for biodiesel production.