Efficient method of synthesizing sn-2 eicosapentaenoic acid (EPA) monoacylglycerols using circular ethanolysis and glycerolysis

The sn-2 monoacylglycerol (MAG) of eicosapentaenoic acid (EPA) can be used as a health-promoting ingredient in functional foods. However, the lack of a good recovery method to prepare high-purity 2-EPA MAGs has limited their application. In this study, circular ethanolysis and glycerolysis were repeated three times to synthesize 2-EPA MAGs and obtain a high recovery of EPA in them. Ethanolysis was carried out using 12 % of Lipozyme 435 and an ethanol-to-triacylglycerol (TAG) ratio of 60, which led to a TAG conversion rate of 97.3 %. Glycerolysis was then carried out using 16 % of CL "Amano" IM and a substrate-to-glycerol ratio of 9 (under vacuum), which led to a conversion rate of ethyl ester to TAGs of 96.8 %. After three ethanolysis-glycerolysis cycles, a relatively high recovery of EPA in the 2-MAG (72.1 %) was obtained. After purification, a high purity 2-EPA MAG product (EPA: 92.2 ± 1.8 %; 2-MAG: 91.50 ± 0.14 %) was obtained.

Lipase-catalyzed esterification for efficient acylglycerols synthesis in a solvent-free system: Process optimization, mass transfer insights and kinetic modeling

Acylglycerols are widely used in the food industry due to their antimicrobial, emulsifying and nutritional properties. This study investigated the key reaction parameters, mass transfer mechanisms, and kinetic features of lipase-catalyzed esterification in a solvent-free system. Taguchi method was further employed to explore the relationship between "reaction parameter - yield composition". The results revealed that the maximum selectivity were achieved fror MAG (57.72 %), DAG (82.67 %) and TAG (79.29 %) under different enzymatic conditions. Fatty acid-to-glycerol molar ratio had the greatest impact on DAG selectivity, contributing 38.08 % of total impact level. Mass transfer analysis showed that external mass transfer limitation could be effectively overcome at stirring speeds above 600 rpm. Kinetic analysis confirmed that the reaction followed the Ping-Pong BiBi mechanism with alcohol and acid inhibition (SSE = 0.000643). This work provided a theoretical basis for developing more efficient and selective catalytic processes, aiding in quality control, reactor design, and industrial scale-up.

The key structure and self-stabilization mechanism of water-soluble interfacial squalene-hopene cyclase

The water insolubility and structural instability of squalene-hopene cyclase (SHC), a membrane-bound interfacial enzyme, pose significant challenges for their use in industrial applications. The membrane-bound nature results in low enzyme yield, cumbersome processes and increased costs. Here, a novel water-soluble catalyst, SaSHC (EC: 5.4.99.17), was discovered from Streptomyces albolongus. This study clearly elucidates its water-soluble structural basis and develop a model for enhancing the water solubility of SHC. The key region, motif 2, contains poly-positively charged amino acids and outward self-anchored structure. The former enhances the electrostatic interaction with the phospholipid head, which makes SaSHC easily dissociated from the cell membrane. And the later ensures the open conformation of the membrane-bound domain. Base on the that, the "outward self-anchored structure dominated-high electrostatic interaction and hydrophobic interaction" (OSA-HELH) model is proposed and applied to optimization SaSHC and AaSHC (from Alicyclobacillus acidocaldarius, tightly bound to the cell membrane). Excitingly, the catalytic efficiency of the SaSHC-L274K was increased by 34.18 %, and mutant AaSHCm2 (AaSHC's motif 2 is replaced by the SaSHC's motif 2) turned into a water-soluble enzyme. In the 100 mL scale-up experiment, the SaSHC-L274K required only 0.04 % Tween 80 to convert 87.82 % squalene, which is an environment-friendly hopene production mode.

A Comprehensive Guide to Enzyme Immobilization: All You Need to Know

Enzyme immobilization plays a critical role in enhancing the efficiency and sustainability of biocatalysis, addressing key challenges such as limited enzyme stability, short shelf life, and difficulties in recovery and recycling, which are pivotal for green chemistry and industrial applications. Classical approaches, including adsorption, entrapment, encapsulation, and covalent bonding, as well as advanced site-specific methods that integrate enzyme engineering and bio-orthogonal chemistry, were discussed. These techniques enable precise control over enzyme orientation and interaction with carriers, optimizing catalytic activity and reusability. Key findings highlight the impact of immobilization on improving enzyme performance under various operational conditions and its role in reducing process costs through enhanced stability and recyclability. The review presents numerous practical applications of immobilized enzymes, including their use in the pharmaceutical industry for drug synthesis, in the food sector for dairy processing, and in environmental biotechnology for wastewater treatment and dye degradation. Despite the significant advantages, challenges such as activity loss due to conformational changes and mass transfer limitations remain, necessitating tailored immobilization protocols for specific applications. The integration of immobilization with modern biotechnological advancements, such as site-directed mutagenesis and recombinant DNA technology, offers a promising pathway for developing robust, efficient, and sustainable biocatalytic systems. This comprehensive guide aims to support researchers and industries in selecting and optimizing immobilization techniques for diverse applications in pharmaceuticals, food processing, and fine chemicals.

Bis-pyrrolidone structures as versatile building blocks for the synthesis of bio-based polyesters and for the preparation of additives

In this work, three bis-pyrrolidone-based structures (BP) were synthesized combining dimethyl itaconate (DMI), the dimethyl ester derivative of itaconic acid, with various aliphatic diamines having a C4 to C12 carbon chain length with the aim of developing novel bio-based building blocks. All three BPs were obtained with a purity >93% and could further be used without performing any tedious purification step, therefore allowing an easy scalability of the synthesis on a 10 g scale. Their potential application was demonstrated in two key areas of modern polymer science: (1) the enzymatic synthesis of polyesters and (2) their use as poly(lactic acid) (PLA) additives. Firstly, the possibility of obtaining oligoesters by reacting the BP monomers with various aliphatic diols in a solventless reaction system and under mild conditions (T < 90 °C) was demonstrated thanks to the use of enzymatic catalysis. Linear oligoesters having mean average molecular weights between 1000 g mol-1 and 6100 g mol-1 and dispersity values <2 were successfully obtained. When applying the BP structures as PLA additives, the incorporation of a 10% w w-1 BP in the polyester matrix resulted in systems with an 8× increased elongation at break and a decrease in the glass transition temperature compared to the neat polymer matrix.

Selective synthesis of triacylglycerols by the ADS-17-supported Candida antarctica lipase B through esterification of oleic acid and glycerol

BACKGROUND

Immobilized enzyme possessing both high activity and good selectivity is important in practice. In this study, Candida antarctica lipase B (CALB) was immobilized onto the macroporous resin ADS-17 for triacylglycerol (TAG) synthesis through esterification of oleic acid and glycerol. The reaction conditions were optimized by single-factor study and orthogonal test, and the reusability of the immobilized CALB (CALB@ADS-17) was evaluated. In addition, the mechanism of lipase immobilization was studied and the catalytic mechanism of CALB@ADS-17 was investigated.

RESULTS

Oleic acid conversion up to 99.20% and TAG content at 91.58 wt% could be obtained under optimal conditions. In addition, the CALB@ADS-17 retained 84.28% of its initial activity after 11 cycles of reuse. The mechanism of lipase immobilization was through hydrophobic adsorption. The relationship between temperature and oleic acid conversion was lnV0 = 6.3316 - 4.3321/T, and the activation energy (Ea) was 36.02 kJ mol-1. CALB@ADS-17 did not exhibit an obvious interfacial activation phenomenon. Its kinetic behavior can be described by the Michaelis-Menten model, whose kinetic parameters of vmax, kcat, Km, Ki, and kcat/Km were 0.01265 μmol L-1 s-1, 9310.72 s-1, 0.4907 mmol L-1, 3.997 mmol L-1, and 1.90 × 104 L mmol-1 s-1, respectively.

CONCLUSION

CALB@ADS-17 showed good esterification performance and exhibited good selectivity towards TAG generation. In addition, CALB@ADS-17 exhibited good reusability in esterification reactions and has potential in practical applications. © 2025 Society of Chemical Industry.

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.

Active Site Studies to Explain Kinetics of Lipases in Organic Solvents Using Molecular Dynamics Simulations

This study investigates the intricate dynamics underlying lipase performance in organic solvents using comprehensive molecular dynamics (MD) simulations, supported by enzyme kinetics data. The study reveals that a single criterion can neither predict nor explain lipase activity in organic solvents, indicating the need for a comprehensive approach. Three lipases were included in this study: Candida antarctica lipase B (CALB), Rhizomucor miehei lipase (RML), and Thermomyces lanuginosus lipase (TLL). The lipases were investigated in acetonitrile, methyl tert-butyl ether, and hexane with increasing water activity. Computational investigations reveal that CALB's activity is negatively correlated to water cluster formations on its surface. In contrast, TLL's and RML's activity profiles show no negative effects of high water activity. However, TLL's and RML's activities are highly correlated to the conformation and stability of their active site regions. This study may pave the way for tailored applications of lipases, highlighting some of the factors that should be considered when lipase-catalyzed reactions are designed.

Recent insight into the advances and prospects of microbial lipases and their potential applications in industry

Enzymes play a crucial role in various industrial sectors. These biocatalysts not only ensure sustainability and safety but also enhance process efficiency through their unique specificity. Lipases possess versatility as biocatalysts and find utilization in diverse bioconversion reactions. Presently, microbial lipases are gaining significant focus owing to the rapid progress in enzyme technology and their widespread implementation in multiple industrial procedures. This updated review presents new knowledge about various origins of microbial lipases, such as fungi, bacteria, and yeast. It highlights both the traditional and modern purification methods, including precipitation and chromatographic separation, the immunopurification technique, the reversed micellar system, the aqueous two-phase system (ATPS), and aqueous two-phase flotation (ATPF), moreover, delves into the diverse applications of microbial lipases across several industries, such as food, vitamin esters, textile, detergent, biodiesel, and bioremediation. Furthermore, the present research unveils the obstacles encountered in employing lipase, the patterns observed in lipase engineering, and the application of CRISPR/Cas genome editing technology for altering the genes responsible for lipase production. Additionally, the immobilization of microorganisms' lipases onto various carriers also contributes to enhancing the effectiveness and efficiencies of lipases in terms of their catalytic activities. This is achieved by boosting their resilience to heat and ionic conditions (such as inorganic solvents, high-level pH, and temperature). The process also facilitates the ease of recycling them and enables a more concentrated deposition of the enzyme onto the supporting material. Consequently, these characteristics have demonstrated their suitability for application as biocatalysts in diverse industries.

Unveiling six novel CALB-like lipases using genome-centric and patent-driven prospection

Lipases present biotechnological applications in various industrial sectors due to their ability to perform multiple biochemical reactions. However, the high cost sometimes discourages their potential uses, besides the extensive number of patents involving them. One of the most utilized and researched lipases is Candida antarctica lipase B (CALB), known for its versatility, encompassing enantioselectivity, thermostability, and a wide range of substrates. Therefore, finding new CALB-like lipases is an interesting strategy to enable the implementation of biocatalysts, especially if intellectual property analysis is included. The present study identified and produced six CALB-like enzymes without patent protection, with differences in pocket amino acids and substrate specificity. We conducted genomic searches in almost 7000 Fungal genomes, identifying over 1500 unique CALB homolog candidates. The phylogenetic and intellectual property analysis filtered those results into a few sequences without protection that were very similar to CALB. One cloned lipase had a lower hydrophobicity at the pocket entrance and preferred the C4 p-nitrophenyl ester as substrate. Another had a wider opening and more polar pocket, showing no preference. These results identified new patent-free lipases with conserved essential catalytic elements and diverse substrate specificity due to variations in the catalytic pocket. These enzymes can be the starting point for biocatalyst innovation with potential applications in diverse biotechnological areas.

PVP-assisted in situ immobilizing lipase on covalent organic framework for enhanced catalytic activity and stability in bioconversions

Covalent organic frameworks (COFs) are crystalline, porous organic materials that have significant potential as supports for enzyme immobilization. Nevertheless, the in situ preparation of biocatalysts during the COF formation process remains a considerable challenge. Herein, we developed a one-pot in situ preparation strategy. The immobilized lipase PS@TPB-TFPB COF-I was fabricated by mixing the polyvinylpyrrolidone (PVP)-lipase PS complex with precursors 1,3,5-tris(4-aminophenyl)benzene (TPB) and 1,3,5-tris(4-formylphenyl)benzene (TFPB) in acetonitrile catalyzed by acetic acid at room temperature for 48 h. The formation mechanism was systematically investigated using time-dependent microscopy techniques. PVP acts as a guiding reagent, controlling the morphological changes that occur during this process. Furthermore, the biocatalyst was employed in the kinetic resolution of racemic 1-phenylethanol, resulting in a significant enhancement in the conversion rate, with a range of 2.1 to 10.6 times higher compared to free PS at the same reaction time. The robust biocatalyst maintained high catalytic activity and enantioselectivity even after 10 cycles. The strategy described here is promising for lipase immobilization and expands the range of applications for COFs in biomanufacturing.

Candida antartica lipase-catalyzed esterification for efficient partial acylglycerol synthesis in solvent-free system: Substrate selectivity, molecular modelling and optimization

Partial acylglycerols are valued for their emulsifying and stabilizing properties, yet precise green synthesis remains challenging due to low yield and selectivity. This study aimed to elucidate the "lipase selectivity-substrate structure-product composition" relationship to enhance the yield of targeted partial acylglycerol. The results showed that lipase exhibited a greater selectivity towards fatty acids with shorter chain lengths and higher unsaturation. Hydroxyl donors also affected the esterification process, with the enzyme-acyl complex exhibiting selectivity towards hydroxyl donors as follows: glycerol > monoacylglycerol > diacylglycerol. Substrate ratio significantly influenced enzymatic reactions; a 10:1 ratio favored triacylglycerol formation (>80 %), while a 1:1 ratio produced > 90 % partial acylglycerols. Molecular docking simulations revealed that substrates primarily interacted with lipase through hydrogen bonding and hydrophobic interactions. A comprehensive understanding of lipase selectivity patterns could facilitate the design of more efficient reaction systems, enabling the conversion of basic lipid resources into desired high value-added products.

Preparation of esculin acetates through transesterification reaction catalyzed by Novozyme 435® and their Purification followed by NMR characterization

In this study, biocatalytic transesterification reaction using Novozyme 435® (N435) lipase was employed to enhance the hydrophobicity of esculin, aiming to improve its solubility for commercial applications and enhance its bioactivity and oral viability. The acylation reaction of esculin with vinyl acetate was conducted at 60 °C and 200 rpm for 24 h. After chromatographic and spectroscopic analysis, two products were identified: the first one was monoacylated at the 6'-OH position of the glucosyl moiety of esculin (TR: 10.3 min and m/z 382.93 [M + H]+), and the second one was diacylated at the 6'-OH and 3'-OH positions (TR: 13.0 min and m/z 424.93 [M + H]+). The latter was the major product, with a conversion rate of 53.550 ± 0.368%, while the monoacetylated one showed 8.715 ± 0.064%. Both products were isolated by high-speed counter-current chromatography (HSCCC) using a two-phase system HEMWat 1:9:1:9 and characterized by NMR. In this way, these results improve the practical application of esculin, through the obtention of esculin mono and diacetates by fast and efficient biocatalysis reaction.

Efficient biotransformation of biobased raw materials into novel polyesters/polyesteramides; comparative investigation of enzymatic synthesis of block and random copolymers and terpolymers

Within the context of paving the way for a sustainable bioeconomy, there is a strong emphasis on utilizing bio-based raw materials as substitutes for fossil fuels in the production of polymers. When designing the synthesis of novel polymeric materials from bio-based building blocks, a promising green approach consists in utilizing enzymes as biocatalysts. This aspect is particularly important when aiming to obtain products from the class of polyesters and polyesteramides with biocompatible and biodegradable properties, as enzymes facilitate the synthesis of polymers that align closely with biological systems. Lipases have been proven to be very effective in the synthesis of polymers, particularly in the ring-opening polymerization of ε-caprolactone. Considering the possibility of performing the copolymerization of ε-caprolactone for obtaining random and block structures, this is the first comparative study of the enzymatic polymer synthesis utilizing an innovative approach of combining ring-opening polymerization with polycondensation. Terpolymers derived from ε-caprolactone and dimethyl itaconate or dimethyl adipate with either 1,8-octanediol or 1,8-octanediamine were obtained at 85 °C in a solventless systems, yielding products with a copolymer content of >85 % and weight-average molecular weight (Mw) up to 40,000 Da. The thermal properties and biodegradation behavior of the synthetized terpolymers were assessed.

Preparation of highly stable immobilized Candida antarctica lipase B (CALB) through adjusting the surface properties of carrier: Preparation, characterization and performance evaluation

The stability of the immobilized lipase is the key factor that determines the economy and feasibility of its industrial application. Here, two robust immobilized Candida antarctica lipase B (CALB) were prepared through adjusting the surface properties of ECR1030 resin. Silane coupling agent (SCA) and dialdehyde cellulose (DAC) were employed to modify the carrier surface. Contact angle measurement showed that the hydrophobicity of the modified carrier increased first, and then decreased with the increase of the chain length of SCA. FTIR results showed that Si-O-Si bond and aldehyde group were attached to ECR1030, respectively, indicating that the ECR1030 resin was successfully modified. Meanwhile, the NH and CN bond were observed in the corresponding immobilized CALB, suggesting CALB was immobilized onto the modified carriers. The effects of immobilization conditions on CALB immobilization was further investigated, and the C8-ECR1030-CALB and DAC-ECR1030-CALB with the activity of 12,736 U/g and 11,962 U/g were obtained. Moreover, the stability of the immobilized lipases was evaluated and compared with the commercial Novozym 435. The C8-ECR1030-CALB and DAC-ECR1030-CALB exhibited comparable or superior stability to Novozym 435 and showed better deacidification effect than Novozym 435. This study paves road for further study involving preparation of highly stable immobilized lipase.

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.

Enzymatic Methoxycarbonylation of Tyrosol and Hydroxytyrosol

Tyrosol and hydroxytyrosol are powerful phenolic antioxidants occurring in olive oil and in by-products from olive processing. Due to their high polarity, esterification or other lipophilization is necessary to make them compatible with lipid matrices. Hydroxytyrosol methyl carbonate is a more effective antioxidant than dibutylhydroxytoluene or α-tocopherol and together with tyrosol methyl carbonate exerts interesting pharmacological properties. The purpose of this work was the enzymatic preparation of alkyl carbonates of tyrosol and hydroxytyrosol. A set of 17 hydrolases was tested in the catalysis of tyrosol methoxycarbonylation in neat dimethyl carbonate to find an economically feasible alternative to the recently reported synthesis of methyl carbonates catalyzed by Novozym 435. Novozym 435 was, however, found to be the best performing catalyst, while Novozym 735, pig pancreatic lipase, lipase F-AK and Lipex 100T exhibited limited reactivity. No enzyme accepted 1,2-propylene carbonate as the acylation donor. Under optimized reaction conditions, Novozym 435 was used in the batch preparation of tyrosol methyl carbonate and hydroxytyrosol methyl carbonate in quantitative yields. The enzymatic methoxycarbonylation of tyrosol and hydroxytyrosol can also be used as a method for their selective protection in enzymatic syntheses of phenylethanoid glycosides catalyzed with enzymes comprising high levels of acetyl esterase side activity.

Accessing Active Fragments for Drug Discovery Utilising Nitroreductase Biocatalysis

Biocatalysis has played a limited role in the early stages of drug discovery. This is often attributed to the limited substrate scope of enzymes not affording access to vast areas of novel chemical space. Here, we have shown a promiscuous nitroreductase enzyme (NR-55) can be used to produce a panel of functionalised anilines from a diverse panel of aryl nitro starting materials. After screening on analytical scale, we show that sixteen substrates could be scaled to 1 mmol scale, with several poly-functional anilines afforded with ease under the standard conditions. The aniline products were also screened for activity against several cell lines of interest, with modest activity observed for one compound. This study demonstrates the potential for nitroreductase biocatalysis to provide access to functional fragments under benign conditions.

Elucidating solvent effects on lipase-catalyzed peroxyacid synthesis through activity-based kinetics and molecular dynamics

Peroxyacid synthesis is the first step in Prilezhaev epoxidation, which is an industrial method to form epoxides. Motivated by the development of a kinetic model as a tool for solvent selection, the effect of solvent type and acid chain length on the lipase-catalyzed peroxyacid synthesis was studied. A thermodynamic activity-based ping-pong kinetic expression was successfully applied to predict the effect of the reagent loadings in hexane. The activity-based reaction quotients provided a prediction of solvent-independent equilibrium constants. However, this strategy did not achieve satisfactory estimations of initial rates in solvents of higher polarity. The lack of compliance with some assumptions of this methodology could be confirmed through molecular dynamics calculations i.e. independent solvation energies and lack of solvent interaction with the active site. A novel approach is proposed combining the activity-based kinetic expression and the free binding energy of the solvent with the active site to predict kinetics upon solvent change. Di-isopropyl ether generated a strong interaction with the enzyme's active site, which was detrimental to kinetics. On the other hand, toluene or limonene gave moderate interaction with the active site rendering improved catalytic yield compared with less polar solvents, a finding sharpened when peroctanoic acid was produced.

Enzymatic Deacidification and Aroma Characteristics Analysis of Rapeseed Oil Using Self-Made Immobilized Lipase CALB@MCM-41-C8

Rapeseed oil is a widely consumed edible oil that contains varieties of beneficial micronutrients such as tocopherols and phytosterols; however, the high acid value due to increased free fatty acid can imperil the oil quality and safety. This paper proposed the enzymatic deacidification for high-acid rapeseed oil and simultaneous production of functional diacylglycerols (DAGs) catalyzed by self-made immobilized lipase CALB@MCM-41-C8. The results indicate that the carrier of molecular sieve MCM-41 exhibited a sufficient surface area of 1439.9 m2/g and a proper pore size of 3.5 nm, promoting the immobilization of lipase CLAB. Under the optimal reaction conditions, the acid value of rapeseed oil was largely decreased from 15.3 mg KOH/g to 1.7 mg KOH/g within 3 h, while DAG content was increased from 1.2% to 40.2%. The antioxidant stability of rapeseed oil was also increased from 4.3 h to 7.6 h after enzymatic deacidification. Besides, the deacidified rapeseed oil exhibited fatty, bitter almond aromas, compared to the picked-vegetable, spicy, and pungent aromas for high-acid oil. Finally, the catalytic stability and applicability of CALB@MCM-41-C8 was validated, thus demonstrating the great potential of CALB@MCM-41-C8 in green refining of edible oils and sustainable synthesis of functional lipids.

Regiocontrol of the Bulk Polymerization of Lysine Ethyl Ester by the Selection of Suitable Immobilized Enzyme Catalysts

The development of a green and facile method for the controlled synthesis of functional polypeptides is desired for sustainable material applications. In this study, the regioselective synthesis of poly(l-lysine) (polyLys) via enzyme-catalyzed aminolysis was achieved by bulk polymerization of l-lysine ethyl ester (Lys-OEt) using immobilized Candida antarctica lipase Novozym 435 (IM-lipase) or trypsin (IM-trypsin). Structural characterization of the obtained polyLys revealed that IM-lipase resulted solely in ε-linked amide bond formation, whereas IM-trypsin predominantly provided α-linked polyLys. Optimization of the conditions for the bulk polymerization using immobilized enzymes resulted in high monomer conversion and a high degree of polymerization, with excellent regioselectivity. Molecular docking simulations revealed different binding conformations of Lys-OEt to the catalytic pockets of lipase and trypsin, which putatively resulted in different amino moieties being used for amide bond formation. The immobilized enzymes were recovered and recycled for bulk polymerization, and the initial activity was maintained in the case of IM-trypsin. The obtained α- and ε-linked polyLys products exhibited different degradability against proteolysis, demonstrating the possibility of versatile applications as sustainable materials. This enzymatic regioregular control enabled the synthesis of well-defined polypeptide-based materials with a diverging structural variety.

Computational studies on the catalytic potential of the double active site for enzyme engineering

Proteins possessing double active sites have the potential to revolutionise enzyme design strategies. This study extensively explored an enzyme that contains both a natural active site (NAS) and an engineered active site (EAS), focusing on understanding its structural and functional properties. Metadynamics simulations were employed to investigate how substrates interacted with their respective active sites. The results revealed that both the NAS and EAS exhibited similar minimum energy states, indicating comparable binding affinities. However, it became apparent that the EAS had a weaker binding site for the substrate due to its smaller pocket and constrained conformation. Interestingly, the EAS also displayed dynamic behaviour, with the substrate observed to move outside the pocket, suggesting the possibility of substrate translocation. To gain further insights, steered molecular dynamics (SMD) simulations were conducted to study the conformational changes of the substrate and its interactions with catalytic residues. Notably, the substrate adopted distinct conformations, including near-attack conformations, in both the EAS and NAS. Nevertheless, the NAS demonstrated superior binding minima for the substrate compared to the EAS, reinforcing the observation that the engineered active site was less favourable for substrate binding due to its limitations. The QM/MM (Quantum mechanics and molecular mechanics) analyses highlight the energy disparity between NAS and EAS. Specifically, EAS exhibited elevated energy levels due to its engineered active site being located on the surface. This positioning exposes the substrate to solvents and water molecules, adding to the energy challenge. Consequently, the engineered enzyme did not provide a significant advantage in substrate binding over the single active site protein. Further, the investigation of internal channels and tunnels within the protein shed light on the pathways facilitating transport between the two active sites. By unravelling the complex dynamics and functional characteristics of this double-active site protein, this study offers valuable insights into novel strategies of enzyme engineering. These findings establish a solid foundation for future research endeavours aimed at harnessing the potential of double-active site proteins in diverse biotechnological applications.

Enzymatic synthesis of pyridine heterocyclic compounds and their thermal stability

An efficient method was discovered for catalyzing the esterification under air using Novozym 435 to obtain pyridine esters. The following conditions were found to be optimal: 60 mg of Novozyme 435, 5.0 mL of n-hexane, a molar ratio of 2:1 for nicotinic acids (0.4 mmol) to alcohols (0.2 mmol), 0.25 g of molecular sieve 3A, a revolution speed of 150 rpm, a reaction temperature of 50 °C, and reaction time of 48 h. Under nine cycles of Novozym 435, the 80 % yield was consistently obtained. Optimum conditions were used to synthesize 23 pyridine esters, including five novel compounds. Among them, gas chromatography-mass spectrometry-olfactometry (GC-MS-O) showed phenethyl nicotinate (3g), (E)-hex-4-en-1-yl nicotinate (3m), and octyl nicotinate (3n) possessed strong aromas. Thermogravimetric analysis (TG) revealed that the compounds 3g, 3m and 3n exhibited stability at the specified temperature. This finding provides theoretical support for adding pyridine esters fragrance to high-temperature processed food.

Efficient regioselective enzymatic acylation of troxerutin: difference characterization of in vitro cellular uptake and cytotoxicity

In this study, we developed a multi-site acylation strategy to improve the lipophilicity and cellular uptake of troxerutin, a natural flavonoid with many health-promoting bioactivities. By clarifying the acylation properties of troxerutin catalyzed by lipases from different sources, a series of troxerutin ester derivatives acylated at different sites was synthesized, including troxerutin dipropyl (TDP), tripropyl (TTP), tetrapropyl (TEP), dibutyl (TDB), monohexyl (TMH), monooctyl (TMO) and monodecyl (TMD) esters. Interestingly, the troxerutin esters acylated at multiple sites with shorter fatty chains (TDP, TTP and TEP) had similar lipophilicity to the mono-acylated esters bearing longer fatty chains (TMH, TMO and TMD, respectively) and meanwhile demonstrated surprisingly lower cytotoxicity than that of the long fatty-chain mono-esters. In particular, the multi-acylated esters with shorter fatty chains showed remarkably higher cellular uptake than the mono-esters with long fatty chains. In vitro gastrointestinal digestion suggested that the multi-acylated esters of troxerutin were more resistant to gastrointestinal degradation than the mono-esters. These results indicated that multi-site acylation with short fatty chains could be an effective alternative to introducing one-site mono-acylation for the modification of troxerutin and other flavonoid compounds.

Microwave-assisted enzymatic synthesis of geraniol esters in solvent-free systems: optimization of the reaction parameters, purification and characterization of the products, and biocatalyst reuse

Various geraniol esters act as insect pheromones and display pharmacological activities, especially as neuroprotective agents. Therefore, the search for synthetic strategies alternative to traditional chemical synthesis could help designing ecofriendly routes for the preparation of such bioactive compounds. Hence, this work aims at the microwave-assisted enzymatic synthesis of geranyl esters in solvent-free systems. The process variables were optimized for the synthesis of geranyl acetoacetate, achieving 85% conversion after 60 min using a 1:5 substrates molar ratio (ester to geraniol), 80 °C and 8.4% of Lipozyme 435 lipase without removal of the co-produced methanol. On the other hand, a 95% conversion was reached after 30 min using 1:6 substrates molar ratio, 70 °C and 7% lipase in the presence of 5Å molecular sieves for the methanol capture. In addition, the lipase showed good reusability, maintaining the same activity for five reaction cycles. Finally, under the above optimized conditions, other geraniol esters were successfully synthetized such as the geranyl butyrate (98%), geranyl hexanoate (99%), geranyl octanoate (98%), and geranyl (R)-3-hydroxybutyrate (56%). These results demonstrate the microwave-assisted lipase-catalyzed transesterification in a solvent-free system as an excellent and sustainable catalytic methodology to produce geraniol esters.

Lipase-catalyzed solvent-free synthesis of monoglycerides from biodiesel-derived crude glycerol: Optimized using response surface methodology

The growth of the biodiesel industry has resulted in significant quantity of crude glycerol. It is necessary to explore the synthesis of high-value-added products from crude glycerol. In this study, the enzymatic synthesis of monoglycerides under solvent-free conditions, employing crude glycerol as the primary feedstock, had been investigated. The analysis showed that the highest yield of monoglycerides was obtained after 12 h, and Novozym 435 showed the highest monoglyceride yield of 18.41 % among the three lipases tested, followed by Lipozyme TL IM and Lipozyme RM IM. Monoglycerides were synthesized from biodiesel-derived crude glycerol using Novozym 435 as the catalyst under solvent-free conditions at different parameters, which were catalyst concentration, substrate molar ratio, and temperature. The yield of monoglycerides was examined in single-factor experiments. Response surface methodology (RSM) was subsequently employed to optimize the synthesis conditions based on the single-factor experimental results. The optimal conditions were at an enzyme concentration of 12.7 wt% and a molar ratio of crude glycerol:oil of 5.7:1 at a reaction temperature of 65.2 °C. The experimental yield of monoglycerides under the optimal conditions was 28.93 %, which is close to the value predicted from the RSM model (29.02 %).

A New Approach in Lipase-Octyl-Agarose Biocatalysis of 2-Arylpropionic Acid Derivatives

The use of lipase immobilized on an octyl-agarose support to obtain the optically pure enantiomers of chiral drugs in reactions carried out in organic solvents is a great challenge for chemical and pharmaceutical sciences. Therefore, it is extremely important to develop optimal procedures to achieve a high enantioselectivity of the biocatalysts in the organic medium. Our paper describes a new approach to biocatalysis performed in an organic solvent with the use of CALB-octyl-agarose support including the application of a polypropylene reactor, an appropriate buffer for immobilization (Tris base-pH 9, 100 mM), a drying step, and then the storage of immobilized lipases in a climatic chamber or a refrigerator. An immobilized lipase B from Candida antarctica (CALB) was used in the kinetic resolution of (R,S)-flurbiprofen by enantioselective esterification with methanol, reaching a high enantiomeric excess (eep = 89.6 ± 2.0%). As part of the immobilization optimization, the influence of different buffers was investigated. The effect of the reactor material and the reaction medium on the lipase activity was also studied. Moreover, the stability of the immobilized lipases: lipase from Candida rugosa (CRL) and CALB during storage in various temperature and humidity conditions (climatic chamber and refrigerator) was tested. The application of the immobilized CALB in a polypropylene reactor allowed for receiving over 9-fold higher conversion values compared to the results achieved when conducting the reaction in a glass reactor, as well as approximately 30-fold higher conversion values in comparison with free lipase. The good stability of the CALB-octyl-agarose support was demonstrated. After 7 days of storage in a climatic chamber or refrigerator (with protection from humidity) approximately 60% higher conversion values were obtained compared to the results observed for the immobilized form that had not been stored. The new approach involving the application of the CALB-octyl-agarose support for reactions performed in organic solvents indicates a significant role of the polymer reactor material being used in achieving high catalytic activity.

Improving the Performance of Photoactive Terpene-Based Resin Formulations for Light-Based Additive Manufacturing

Photocurable liquid formulations have been a key research focus for the preparation of mechanically robust and thermally stable networks. However, the development of renewable resins to replace petroleum-based commodities presents a great challenge in the field. From this perspective, we disclose the design of photoactive resins based on terpenes and itaconic acid, both potentially naturally sourced, to prepare photosets with adjustable thermomechanical properties. Biobased perillyl itaconate (PerIt) was synthesized from renewable perillyl alcohol and itaconic anhydride via a scalable solvent-free method. Photoirradiation of PerIt in the presence of a multiarm thiol and photoinitiator led to the formation of networks over a range of compositions. Addition of nonmodified terpenes (perillyl alcohol, linalool, or limonene) as reactive diluents allowed for more facile preparation of photocured networks. Photosets within a wide range of properties were accessed, and these could be adjusted by varying diluent type and thiol stoichiometry. The resins showed rapid photocuring kinetics and the ability to form either brittle or elastic materials, with Young's modulus and strain at break ranging from 3.6 to 358 MPa and 15 to 367%, respectively, depending on the chemical composition of the resin. Glass transition temperatures (Tg) were influenced by thioether content, with temperatures ranging from 5 to 43 °C, and all photosets displayed good thermal resistance with Td,5% > 190 °C. Selected formulations containing PerIt and limonene demonstrated suitability for additive manufacturing technologies and high-resolution objects were printed via digital light processing (DLP). Overall, this work presents a simple and straightforward route to prepare renewable resins for rapid prototyping applications.

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.

Intensification of Enzymatic Sorbityl Laurate Production in Dissolved and Neat Systems under Conventional and Microwave Heating

Glycolipids such as sugar alcohol esters have been demonstrated to be relevant for numerous applications across various domains of specialty. The use of organic solvents and, more recently, deep eutectic solvents (DESs) to mediate lipase-supported bioconversions is gaining potential for industrial application. However, many challenges and limitations remain such as extensive time of production and relatively low productivities among others, which must be solved to strengthen such a biocatalytic process in industry. In this context, this study focuses on the intensification of sorbityl laurate production, as a model biocatalyzed reaction using Novozym 435, investigating the relevance of temperature, heating method, and solvent system. By increasing the reaction temperature from 50 to 90 °C, the space-time yield and product yield were considerably enhanced for reactions in DES and the organic solvent 2M2B, irrespective of the heating method (conventional or microwave heating). However, positive effects in 2M2B were more pronounced with conventional heating as 98% conversion yield was reached within 90 min at 90 °C, equating thus to a nearly 4-fold increase in performance yielding 118.0 ± 3.6 g/(L·h) productivity. With DES, the overall yield and space-time yield were lower with both heating methods. However, microwave heating enabled a 2-fold increase in both performance parameters when the reaction temperature was increased from 50 to 90 °C. Compared to conventional heating, a 7-fold increase in space-time yield at 50 °C and a 16-fold increase at 90 °C were achieved in DES by microwave heating. Furthermore, microwave irradiation enabled the usage of a neat, solvent-free system, representing an initial proof of concept with productivities of up to 13.3 ± 2.3 g/(L·h).

Enhancing biocatalyst performance through immobilization of lipase (Eversa® Transform 2.0) on hybrid amine-epoxy core-shell magnetic nanoparticles

Magnetic nanoparticles were functionalized with polyethylenimine (PEI) and activated with epoxy. This support was used to immobilize Lipase (Eversa® Transform 2.0) (EVS), optimization using the Taguchi method. XRF, SEM, TEM, XRD, FTIR, TGA, and VSM performed the characterizations. The optimal conditions were immobilization yield (I.Y.) of 95.04 ± 0.79 %, time of 15 h, ionic load of 95 mM, protein load of 5 mg/g, and temperature of 25 °C. The maximum loading capacity was 25 mg/g, and its stability in 60 days of storage showed a negligible loss of only 9.53 % of its activity. The biocatalyst demonstrated better stability at varying temperatures than free EVS, maintaining 28 % of its activity at 70 °C. It was feasible to esterify free fatty acids (FFA) from babassu oil with the best reaction of 97.91 % and ten cycles having an efficiency above 50 %. The esterification of produced biolubricant was confirmed by NMR, and it displayed kinematic viscosity and density of 6.052 mm2/s and 0.832 g/cm3, respectively, at 40 °C. The in-silico study showed a binding affinity of -5.8 kcal/mol between EVS and oleic acid, suggesting a stable substrate-lipase combination suitable for esterification.

Improved biocatalytic activity of steapsin lipase in supercritical carbon dioxide medium for the synthesis of benzyl butyrate: A commercially important flavour compound

Enzymatic synthesis of flavours, fragrances and food additives compounds have great demand and market value. Benzyl butyrate is commercially important flavour and food additive compound having global use around 100 metric tons/year and widely used in various industrial sectors. However, industrial synthesis of food additive benzyl butyrate is carried out by conventional chemical process which demands for the green biobased sustainable synthetic process. The present work reports steapsin catalyzed synthesis of benzyl butyrate for the first time in supercritical carbon dioxide (Sc-CO2) reaction medium. All reaction variables are optimized in details to obtain competent conversion of 99% in Sc-CO2 reaction medium. The developed steapsin catalyzed synthesis in Sc-CO2 medium offered almost four-fold higher conversion to benzyl butyrate than organic (conventional) solvent. The steapsin biocatalyst was effectually recycled up to five reaction cycles in Sc-CO2 medium. Moreover, the developed steapsin catalyzed protocol in Sc-CO2 medium was extended to synthesize different ten industrially significant flavour fragrance compounds that offers 99% conversion and three to five-folds higher conversion than organic medium. Thus, the present steapsin catalyzed protocol offered improved synthesis of various commercially significant flavour compounds in Sc-CO2. medium.

Biocatalytic Regioselective O-acylation of Sesquiterpene Lactones from Chicory: A Pathway to Novel Ester Derivatives

We report the first biocatalytic modification of sesquiterpene lactones (STLs) found in the chicory plants, specifically lactucin (Lc), 11β,13-dihydrolactucin (DHLc), lactucopicrin (Lp), and 11β,13-dihydrolactucopicrin (DHLp). The selective O-acylation of their primary alcohol group was carried out by the lipase B from Candida antarctica (CAL-B) using various aliphatic vinyl esters as acyl donors. Perillyl alcohol, a simpler monoterpenoid, served as a model to set up the desired O-acetylation reaction by comparing the use of acetic acid and vinyl acetate as acyl donors. Similar conditions were then applied to DHLc, where five novel ester chains were selectively introduced onto the primary alcohol group, with conversions going from >99 % (acetate and propionate) to 69 % (octanoate). The synthesis of the corresponding O-acetyl esters of Lc, Lp, and DHLp was also successfully achieved with near-quantitative conversion. Molecular docking simulations were then performed to elucidate the preferred enzyme-substrate binding modes in the acylation reactions with STLs, as well as to understand their interactions with crucial amino acid residues at the active site. Our methodology enables the selective O-acylation of the primary alcohol group in four different STLs, offering possibilities for synthesizing novel derivatives with significant potential applications in pharmaceuticals or as biocontrol agents.

Enzymes in "Green" Synthetic Chemistry: Laccase and Lipase

Enzymes play an important role in numerous natural processes and are increasingly being utilized as environmentally friendly substitutes and alternatives to many common catalysts. Their essential advantages are high catalytic efficiency, substrate specificity, minimal formation of byproducts, and low energy demand. All of these benefits make enzymes highly desirable targets of academic research and industrial development. This review has the modest aim of briefly overviewing the classification, mechanism of action, basic kinetics and reaction condition effects that are common across all six enzyme classes. Special attention is devoted to immobilization strategies as the main tools to improve the resistance to environmental stress factors (temperature, pH and solvents) and prolong the catalytic lifecycle of these biocatalysts. The advantages and drawbacks of methods such as macromolecular crosslinking, solid scaffold carriers, entrapment, and surface modification (covalent and physical) are discussed and illustrated using numerous examples. Among the hundreds and possibly thousands of known and recently discovered enzymes, hydrolases and oxidoreductases are distinguished by their relative availability, stability, and wide use in synthetic applications, which include pharmaceutics, food and beverage treatments, environmental clean-up, and polymerizations. Two representatives of those groups-laccase (an oxidoreductase) and lipase (a hydrolase)-are discussed at length, including their structure, catalytic mechanism, and diverse usage. Objective representation of the current status and emerging trends are provided in the main conclusions.

Recent advances on erythorbyl fatty acid esters as multi-functional food emulsifiers

Over the past few decades, food scientists have investigated a wide range of emulsifiers to manufacture stable and safe emulsion-based food products. More recently, the development of emulsifiers with multi-functionality, which is the ability to have more than two functions, has been considered as a promising strategy for resolving rancidification and microbial contamination in emulsions. Erythorbyl fatty acid esters (EFEs) synthesized by enzymatic esterification of hydrophilic erythorbic acid and hydrophobic fatty acid have been proposed as multi-functional emulsifiers since they simultaneously exhibit amphiphilic, antioxidative, and antibacterial properties in both aqueous and emulsion systems. This review provides current knowledge about EFEs in terms of enzymatic synthesis and multi-functionality. All processes for synthesizing and identifying EFEs are discussed. Each functionality of EFEs and the proposed mechanism are described with analytical methodologies and experimental details. It would provide valuable insights into the development and application of a multi-functional emulsifier in food emulsion chemistry.

Excellence in Acrylation - Scope and Limitation of Glucosyl Imidazolium-coated Novozym 435 Catalyzed (Meth)acryl Ester Synthesis

The incorporation of carbohydrate based ionic liquids as a support for Novozym 435 was previously studied by the authors for the acrylation of n-butanol as the target substrate, which was used as the foundation for the design of experiments. The combination of carbohydrate based ionic liquids and Novozym 435 remains a key aspect of this work. Building upon this, the reaction parameters were optimized for the Novozym catalyst. Substrate screening was performed to explore the scope and limitations of room temperature acrylation reactions. Herein, different alcohols and reaction conditions were screened extensively for the different acrylate products with yields of up to 99.9 % determined via gas chromatography (GC). Standard straight chain alcohols, 2-functionalized ethanol derivatives with electron donating and withdrawing groups, and more sterically challenging substrates were investigated over a broad concentration region. To further underline the applicability of the modified biocatalyst, two alcohols were converted with methacrylic acid. The presented method offers a greener pathway for acrylate synthesis, which eliminates the need for high reaction temperatures, strongly acidic catalysts and/or polymerization inhibitors as used in non-biocatalytic acrylate synthesis.

Enzyme-linked carbon nanotubes as biocatalytic tools to degrade and mitigate environmental pollutants

A wide array of organic compounds have been recognized as pollutants of high concern due to their controlled or uncontrolled presence in environmental matrices. The persistent prevalence of diverse organic pollutants, including pharmaceutical compounds, phenolic compounds, synthetic dyes, and other hazardous substances, necessitates robust measures for their practical and sustainable removal from water bodies. Several bioremediation and biodegradation methods have been invented and deployed, with a wide range of materials well-suited for diverse environments. Enzyme-linked carbon-based materials have been considered efficient biocatalytic platforms for the remediation of complex organic pollutants, mostly showing over 80% removal efficiency of micropollutants. The advantages of enzyme-linked carbon nanotubes (CNTs) in enzyme immobilization and improved catalytic potential may thus be advantageous for environmental research considering the current need for pollutant removal. This review outlines the perspective of current remediation approaches and highlights the advantageous features of enzyme-linked CNTs in the removal of pollutants, emphasizing their reusability and stability aspects. Furthermore, different applications of enzyme-linked CNTs in environmental research with concluding remarks and future outlooks have been highlighted. Enzyme-linked CNTs serve as a robust biocatalytic platform for the sustainability agenda with the aim of keeping the environment clean and safe from a variety of organic pollutants.

Esters in the Food and Cosmetic Industries: An Overview of the Reactors Used in Their Biocatalytic Synthesis

Esters are versatile compounds with a wide range of applications in various industries due to their unique properties and pleasant aromas. Conventionally, the manufacture of these compounds has relied on the chemical route. Nevertheless, this technique employs high temperatures and inorganic catalysts, resulting in undesired additional steps to purify the final product by removing solvent residues, which decreases environmental sustainability and energy efficiency. In accordance with the principles of "Green Chemistry" and the search for more environmentally friendly methods, a new alternative, the enzymatic route, has been introduced. This technique uses low temperatures and does not require the use of solvents, resulting in more environmentally friendly final products. Despite the large number of studies published on the biocatalytic synthesis of esters, little attention has been paid to the reactors used for it. Therefore, it is convenient to gather the scattered information regarding the type of reactor employed in these synthesis reactions, considering the industrial field in which the process is carried out. A comparison between the performance of the different reactor configurations will allow us to draw the appropriate conclusions regarding their suitability for each specific industrial application. This review addresses, for the first time, the above aspects, which will undoubtedly help with the correct industrial implementation of these processes.

Regiospecificity of Immobilized Candida antarctica Lipase B (CAL-B) towards 2,3-Diacyl-1-O-alkyl Glyceryl Ether in Ethanol

Highly pure 2,3-dioleoyl-1-O-alkyl glyceryl ether (DOGE), whose 1-position is a lipase-tolerant ether bond, was chemically synthesized and its detailed regioselectivity and acyl transfer were confirmed. During ethanolysis using immobilized Candida antarctica lipase B (CAL-B) with DOGE as the substrate, monooleoyl-1-O-alkyl glyceryl ethers (MOGEs) and a few 1-alkyl glyceryl ethers were formed upon consumption of the substrate. The structure of MOGE was confirmed using nuclear magnetic resonance spectroscopy and only the isomer of 2-MOGE was formed, indicating that CAL-B has complete α- regiospecificity. During ethanolysis, 3-MOGE was formed via acyl migration. These results indicate that the formation of 1-alkyl glyceryl ethers is not due to the imperfect regiospecificity of CAL-B, but rather due to ethanolysis of the formed 3-MOGE. The ethanolysis rate at the 3-α-position of DOGE was faster and the rate of acyl transfer was slightly slower for chain lengths greater than 14. These results show for the first time that both deacylation at the 3-position and acyl migration from the 2- to 3-position are affected by the structure of 1-position.

Biocatalysts Based on Immobilized Lipases for the Production of Fatty Acid Ethyl Esters: Enhancement of Activity through Ionic Additives and Ion Exchange Supports

Ionic additives affect the structure, activity and stability of lipases, which allow for solving common application challenges, such as preventing the formation of protein aggregates or strengthening enzyme-support binding, preventing their desorption in organic media. This work aimed to design a biocatalyst, based on lipase improved by the addition of ionic additives, applicable in the production of ethyl esters of fatty acids (EE). Industrial enzymes from Thermomyces lanuginosus (TLL), Rhizomucor miehei (RML), Candida antárctica B (CALB) and Lecitase®, immobilized in commercial supports like Lewatit®, Purolite® and Q-Sepharose®, were tested. The best combination was achieved by immobilizing lipase TLL onto Q-Sepharose® as it surpassed, in terms of %EE (70.1%), the commercial biocatalyst Novozyme® 435 (52.7%) and was similar to that of Lipozyme TL IM (71.3%). Hence, the impact of ionic additives like polymers and surfactants on both free and immobilized TLL on Q-Sepharose® was assessed. It was observed that, when immobilized, in the presence of sodium dodecyl sulfate (SDS), the TLL derivative exhibited a significantly higher activity, with a 93-fold increase (1.02 IU), compared to the free enzyme under identical conditions (0.011 IU). In fatty acids ethyl esters synthesis, Q-SDS-TLL novel derivatives achieved results similar to commercial biocatalysts using up to ~82 times less enzyme (1 mg/g). This creates an opportunity to develop biocatalysts with reduced enzyme consumption, a factor often associated with higher production costs. Such advancements would ease their integration into the biodiesel industry, fostering a greener production approach compared to conventional methods.

An expeditive and green chemo-enzymatic route to diester sinapoyl-l-malate analogues: sustainable bioinspired and biosourced UV filters and molecular heaters

Sinapoyl malate, naturally present in plants, has proved to be an exceptional UV filter and molecular heater for plants. Although there are nowadays industrially relevant sustainable synthetic routes to sinapoyl malate, its incorporation into certain cosmetic formulations, as well as its adsorption on plant leaves, is limited by its hydrophilicity. To overcome these obstacles, it is important to find a way to effectively control the hydrophilic-lipophilic balance of sinapoyl malate to make it readily compatible with the cosmetic formulations and stick on the waxy cuticle of leaves. To this end, herein, we describe a highly regioselective chemo-enzymatic synthesis of sinapoyl malate analogues possessing fatty aliphatic chains of variable length, enabling the lipophilicity of the compounds to be modulated. The potential toxicity (i.e., mutagenicity, carcinogenicity, endocrine disruption, acute and repeated-dose toxicity), bioaccumulation, persistence and biodegradability potential of these new analogues were evaluated in silico, along with the study of their transient absorption spectroscopy, their photostability as well as their photodegradation products.

Do they make a good match? Molecular dynamics studies on CALB-catalyzed esterification of 3-phenylpropionic and cinnamic acids

Lipases are versatile catalysts widely used in industrial biotransformations and laboratory-scale developed reactions with industrial potential. Despite the fact that lipase B from Candida antarctica (CALB) is one of the most widely used lipolytic enzymes, its substrate specificity is still poorly understood. One observed trend is that reactions carried out with carboxylic acids containing a double bond are less efficient on average. Here, we have utilized a combination of in vitro and in silico techniques, to better understand the negative impact of a double bond on CALB-mediated esterification. Then through extensive molecular dynamics (MD) simulations, we were able to map the entry pathway of cinnamic acid and its derivative into the CALB active site, and their interactions with catalytic residues. We observed a 2 step binding mechanism of studied compounds, where they first penetrate the enzyme pocket in a conformation where their carboxylic groups are extended towards the solvent. This is followed by further penetration of the acid into the enzymatic active pocket, and a full rotation within the active site, which orients the acid in a conformation that allows further steps of the esterification reaction. As acids containing a double bond are more rigid, their mobility and thus ability to rotate in the narrow CALB active site is hampered, which provides a structural explanation for the decreased efficiency of such acids. Our data provide insight into the substrate specificity of CALB-mediated esterification, providing important structural guidelines to better understand and potentially improve the efficiency of such reactions.

Isolation of Fatty Acids from the Enzymatic Hydrolysis of Capsaicinoids and Their Use in Enzymatic Acidolysis of Coconut Oil

Herein we report the optimization of enzymatic hydrolysis of a mixture of capsaicinoids, capsaicin and dihydrocapsaicin obtained from chili peppers, and the utilization of the isolated fatty acids for the modification of coconut oil using enzyme catalyzed acidolysis. This work was carried out as the fatty acids that can be isolated from capsaicinoid hydrolysis have been shown to possess interesting biological properties. These biological properties could be better exploited by incorporating the fatty acids into a suitable delivery vehicle. The enzymatic hydrolysis of the mixture of capsaicin and dihydrocapsaicin was carried out using Novozym® 435 in phosphate buffer (pH 7.0) at 50℃. The enzyme catalyst could be reused in multiple cycles of the hydrolysis reaction. The desired 8-methyl-6-trans-nonenoic acid and 8-methylnonanoic acid were isolated from the hydrolysis reaction mixture using a simple extraction procedure with a 47.8% yield. This was carried out by first extracting the reaction mixture at pH 10 with ethyl acetate to remove any dissolved capsaicinoids and vanillyl amine side product. The fatty acids were isolated after adjustment of the pH of the reaction mixture to 5 and second extraction with ethyl acetate. The acidolysis of coconut oil with the obtained fatty acids was performed using Lipozyme® TL IM. The performance of the acidolysis reaction was evaluated using 1H-NMR spectroscopy and verified in selected cases using gas chromatography. The best performing conditions involved carrying out the acidolysis reaction at 60℃ with a 1.2 w/w ratio of the fatty acids to coconut oil and 10% enzyme loading for 72 h. This resulted in the incorporation of 26.61% and 9.86% of 8-methyl-6-trans-nonenoic acid and 8-methylnonanoic acid, respectively, into the modified coconut oil product. This product can act as a potential delivery vehicle for these interesting compounds.

Chemo- and regio-selective enzymatic lipophilisation of rutin, and physicochemical and antioxidant properties of rutin ester derivatives

Enzymes are one of the most powerful tools in organic Green Chemistry and enzymatic reactions offer numerous advantages like regio- and enantio-selectivity along with their eco-friendly and sustainable nature. More specifically, lipases can catalyse both ester hydrolysis and formation depending on the nature of the substrate and water content. Herein, the focus is on the development of an enzymatically catalysed lipophilisation of natural compounds using lipases of microbial origin and the investigation of the optimal reaction conditions, aiming ultimately to ameliorate the compounds' properties. The flavonoid disaccharide rutin (quercetin-3-O-rutinoside) was the model compound on which the acylation protocol was built, allowing an efficient procedure to be established, while simultaneously offering the possibility of developing rapid, clear and robust methodologies, using state-of-the-art techniques, for analysis and purification of the synthesized compounds. An optimal 72 h reaction at 55 °C, using Candida antarctica lipase B immobilized on acrylic resin, combined with silicon dioxide as dehydrating agent, followed by product purification, achieved conversion ratios up to 50%. Full characterization and evaluation of the physicochemical and antioxidant properties of the esterified compounds was obtained. The lipophilicity of the rutin esters produced increased with increasing alkyl chain length, yet antioxidant properties were unaffected in comparison with the parent compound. A preparatively useful acylation protocol was established, allowing full investigation into the properties of the acylated compounds. It is also applicable for use on mixtures of compounds as most natural products are found in nature in mixtures and such a development greatly enhances the potential of this method for future commercial applications.

Lipase catalysis: an environmentally friendly production for polyol esters (biolubricant) from microalgae oil

ABSTRACTThis study aims to investigate the optimized lipase-catalysed esterification reaction from novel feedstock microalgae (Chlorella protothecoides) oil-free fatty acids (FFAs) for biolubricant (Trimethylolpropane (TMP)-triesters) synthesis. FFAs were obtained from microalgae oil by enzymatic hydrolysis. Response surface methodology (RSM) with the central composite design was performed to investigate the effect of experimental factors (lipase amount, TMP/FFAs molar ratio, reaction temperature) on the FFAs conversion and also investigated to resolve the optimum design points. After the experimental studies, the highest FFAs conversion of 93% with 92% triester and 8% mono, di esters contents were found when the lipase amount was 5.5%. TMP/FFAs molar ratio was 0.33 and the reaction temperature value was 60°C. The model fitted with the experimental values with R2 = 0.97. It was also supported by gas chromatography and FTIR analyses that the product obtained was a lubricant.

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.

Total Syntheses of Polycyclic Diterpenes Phomopsene, Methyl Phomopsenonate, and iso-Phomopsene via Reorganization of C-C Single Bonds

The first total syntheses of polycyclic diterpenes phomopsene (1), methyl phomopsenonate (2), and iso-phomopsene (3) have been accomplished through the unusual cascade reorganization of C-C single bonds. This approach features: (i) a synergistic Nazarov cyclization/double ring expansions in one-step, developed by authors, to rapid and stereospecific construction of the 5/5/5/5 tetraquinane scaffold bearing contiguous quaternary centers and (ii) a one-pot strategic ring expansion through Beckmann fragmentation/recombination to efficiently assemble the requisite 5/5/6/5 tetracyclic skeleton of the target molecules 1-3. This work enables us to determine that the correct structure of iso-phomopsene is, in fact, the C7 epimer of the originally assigned structure. Finally, the absolute configurations of three target molecules were confirmed through enantioselective synthesis.

Energetic and Kinetic Origins of CALB Interfacial Activation Revealed by PaCS-MD/MSM

The conformational dynamics of Candida antarctica lipase B (CALB) was investigated by molecular dynamics (MD) simulation, parallel cascade selection MD (PaCS-MD), and the Markov state model (MSM) and mainly focused on the lid-opening motion closely related to substrate binding. All-atom MD simulation of CALB was conducted in water and on the interface of water and tricaprylin. CALB initially situated in water and separated by layers of water from the interface is spontaneously adsorbed onto the tricaprylin surface during MD simulation. The opening and closing motions of the lid are simulated by PaCS-MD, and subsequent MSM analysis provided the free-energy landscape and time scale of the conformational transitions among the closed, semiopen, and open states. The closed state is the most stable in the water system, but the stable conformation in the interface system shifts to the semiopen state. These effects could explain the energetics and kinetics origin of the previously reported interfacial activation of CALB. These findings could help expand the application of CALB toward a wide variety of substrates.

Non-Native Site-Selective Enzyme Catalysis

The ability to site-selectively modify equivalent functional groups in a molecule has the potential to streamline syntheses and increase product yields by lowering step counts. Enzymes catalyze site-selective transformations throughout primary and secondary metabolism, but leveraging this capability for non-native substrates and reactions requires a detailed understanding of the potential and limitations of enzyme catalysis and how these bounds can be extended by protein engineering. In this review, we discuss representative examples of site-selective enzyme catalysis involving functional group manipulation and C-H bond functionalization. We include illustrative examples of native catalysis, but our focus is on cases involving non-native substrates and reactions often using engineered enzymes. We then discuss the use of these enzymes for chemoenzymatic transformations and target-oriented synthesis and conclude with a survey of tools and techniques that could expand the scope of non-native site-selective enzyme catalysis.