Interfacial Activation of Candida antarctica Lipase B: Combined Evidence from Experiment and Simulation

Effect of the support alkyl chain nature in the functional properties of the immobilized lipases

Supports coated with amino-hexyl and amino octyl have been prepared from glyoxyl agarose beads and compared in their performance with octyl-agarose to immobilize lipases A and B from Candida antarctica (CALA and CALB). Immobilization courses were similar using all supports, but enzyme release was more difficult using the amino-alkyl supports suggesting a mixed interfacial activation/ionic exchange immobilization. The enzyme activity and specificity (using p-nitrophenyl propionate, triacetin and both isomers of methyl mandelate) greatly depended on the support. In many instances the enzymes immobilized on the new supports offered higher activities and enantiospecificity in the hydrolysis of both enantiomers of methyl mandelate (mainly using CALB). This was coupled to a lower enzyme stability using the new supports, even in the presence of high ionic strength, suggesting that the amphipathic could be responsible of the enzyme lower stability. Using CALB, it was possible to detect a higher exposition of the enzyme Trp groups to the medium by florescence spectra after its immobilization on the amino-alkyl-supports, correlating to the higher activity and lower stability results.

Further Characterization of Lipase B from Ustilago maydis Expressed in Pichia pastoris: a Member of the Candida antarctica Lipase B-like Superfamily

Lipases from the basidiomycete fungus Ustilago maydis are promising but underexplored biocatalysts due to their high homology with Candida antarctica lipases. This study provides a comprehensive characterization of a recombinant CALB-like lipase from U. maydis, expressed in Pichia pastoris (rUMLB), and compares its properties with those of the well-studied recombinant lipase B from C. antarctica (rCALB). Biochemical analyses included evaluations of optimal pH, temperature, triglyceride (TG) preference for short- and medium-chain acyl groups, phospholipase and amidase activities, enantiopreference, thermostability, stability in organic solvents, and response to NaCl concentrations. rUMLB, a glycosylated enzyme with a molecular weight of 38.6 kDa, exhibited cold-active behavior at 0 °C and preferred hydrolysis of partially soluble short-chain fatty acid TGs, like rCALB. In addition, rUMLB was also capable of hydrolyzing insoluble long-chain triglycerides like rCALB. The half-life at 50 °C for rCALB was approximately 1.6 times greater than that of UMLB, which has fewer surface-exposed proline residues. Both enzymes displayed strong (R)-enantiopreference on (R)-glycidyl butyrate, (R)-ethyl hydroxy butyrate, and (R)-methyl hydroxy valerate enantiomers with increased activity in non-polar solvents. However, rUMLB was more sensitive to polar solvents. Notably, rUMLB was activated at high NaCl concentrations, as previously reported for rCALB. rUMLB showed amidase activity on capsaicinoids similar to rCALB; however, rUMLB uniquely demonstrated significant phospholipase activity toward natural phospholipids, a feature not observed in rCALB. The analysis of the cavity adjacent to the active site in the UMLB model and CALB structure revealed slightly larger area, volume, and hydrophobicity values for UMLB. These comparative insights highlight the functional diversity within the CALB-type lipase family, underscoring the potential of UMLB as a versatile biocatalyst and providing valuable information for biotechnological applications and for understanding enzyme structure-function relationships within the CALB superfamily.

The activity regulation of lipase from Aspergillus fumigatus by ligand through allosteric exploration

Lipase activity from Aspergillus fumigatus (AFL) were modulated by an effector (HMD) that was discovered for an allosteric site on the bioactive macromolecule. Experimental evaluation and computational modeling of allosteric effects revealed alterations in the structure of AFL. It was found that AFL's activity in HMD solution increased by approximately 46 % due to mainly enhanced lid flexibility. HMD-AFL interaction was driven by enthalpy and entropy. However, when AFL was coupled to HMD-modified microspheres (PS-HMD-p), its hydrolysis activity decreased by ∼14.3 % due to reduced lid flexibility. After immobilization, AFL's ester-synthesis activity also decreased, due to changes in the conformational dynamics and the geometric characteristics of active site. Investigating the structural dynamics of allosteric regulation of the lipase not only reveals its structural changes underlying the functional variation but also enhances the understanding of the allosteric property that is underappreciated in exoenzymes.

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.

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.

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.

Investigation on solvent-free esterification of oleic acid by hemp tea waste-immobilized Candida rugosa lipase

This study aimed at Candida rugosa lipase immobilization on a low-cost and readily available support. Among agro-industrial crops, hemp tea waste was chosen as the carrier because it provides higher immobilization performance than hemp flower and leaf wastes. Support characterization by ATR-FTIR, SEM and elemental analysis and the optimization of the adsorption immobilization process were performed. The lipase adsorption immobilization was obtained by soaking the support with hexane under mild agitation for 2 h and a successively incubating the enzyme for 1 h at room temperature without removing the solvent. The esterification of oleic acid with n-decanol was tested in a solvent-free system by studying some parameters that influence the reaction, such as the substrates molar ratio, the lipase activity/oleic acid ratio, reaction temperature and the presence/absence of molecular sieves. The biocatalyst showed the ability to bring the esterification reaction to equilibrium under 60 min and good reusability (maintaining 60 % of its original activity after three successive esterification reactions) but low conversion (21 %) at the optimized conditions (40 °C, 1:2 substrates molar ratio, 0.56 lipase/oleic acid ratio, without sieves). Comparing the results with those obtained by free lipase form at the same activity (1 U) and experimental conditions, slightly higher conversion (%) appeared for the free lipase. All this highlighted that probably the source of lipase for its carbohydrate-binding pocket and lid structure affected the esterification of oleic acid but certainly, the immobilization didn't induce any lipase conformational change also allowing the reuse of the catalytic material.

Hydrophobic Residues Promote Interfacial Activation of Candida rugosa Lipase: A Study of Rotational Dynamics

Microbial lipases constitute a class of biocatalysts with the ability to cleave ester linkages of long-chain triglycerides. This property makes them particularly attractive for industrial applications ranging from food processing to pharmaceutical preparation. Among such enzymes, Candida rugosa lipase (CRL) is one of the most frequently used in biotransformation. A notable feature of CRL, among many lipases, is its propensity for interfacial activation: these enzymes exhibit elevated catalytic rates when acting at the interface between aqueous and hydrophobic phases. Notably, this phenomenon can be attributed to the presence of a mobile lid domain, which in its closed state occludes the enzyme active site. To advance our understanding of interfacial activation, we explore the dynamics of CRL rotation at the octane-water interface in this work. To do so, we employ molecular dynamics and umbrella sampling to evaluate the free energy of rotation of the enzyme at the interface. We identify a global minimum in the rotational landscape that coincides with lid opening at the interface. Additionally, we investigate the role of surface residues outside the lid domain as they serve to instigate rotation of the lid toward the aqueous phase. In doing so, we identify a patch of leucine residues which when mutated to glycine impose a barrier to rotation that maintains the enzyme in the inactive (closed lid) state on the order of 1 μs. Importantly, this study presents a novel quantification of the rotational free energy corresponding to CRL lid opening at the octane-water interface. The accompanying mutagenesis study likewise clarifies the role of hydrophobic surface residues in the transition. As such, this work provides valuable insight into the phenomenon of interfacial activation that might open up new avenues for manipulating the microenvironment of industrially relevant lipases, affording enhanced control over the enzyme state.

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.

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.

Lipase B from Candida antarctica immobilized on amphiphilic Janus halloysite nanosheet and application in biphasic interface conversion

Lipase B from Candida antarctica (CALB) plays a prominent role as a biocatalyst in several industries, especially for biphasic conversion of functional lipids. Herein, an amphiphilic Janus halloysite nanosheet (JHNS) was fabricated and employed simultaneously as a solid surfactant for stabilizing Pickering emulsion and as a carrier for immobilizing CALB, with the aim to realize highly efficient biphasic bioconversion. The obtained JHNS could stabilize Pickering emulsion for at least 7 days. Immobilization of CALB on JHNS improved the substrate affinity, catalytic efficiency, thermal stability, and alkaline tolerance of the enzyme. Moreover, JHNS-based immobilized CALB was exploited as a biocatalytic platform for the conversion of retinyl acetate, with almost twice increase in conversion efficiency. Taken together, the JHNS-based immobilized CALB paves the way for the design of efficient biphasic conversion system for the production of added-value lipids.

Improved lipase performance by covalent immobilization of Candida antarctica lipase B on amino acid modified microcrystalline cellulose as green renewable support

Development of immobilized lipase with excellent catalytic performance and low cost is the major challenge for large-scale industrial applications. In this study, green renewable microcrystalline cellulose (MCC) that was hydrophobically modified with D-alanine (Ala) or L-lysine (Lys) was used for immobilizing Candida antarctica lipase B (CALB). The improved catalytic properties were investigated by experimental and computational methods. CALB immobilized on MCC-Ala with higher hydrophobicity showed better catalytic activity than CALB@MCC-Lys because the increased flexibility of the lid region of CALB@MCC-Ala favored the formation of open conformation. Additionally, the low root mean square deviation and the high β-sheet and α-helix contents of CALB@MCC-Ala indicated that the structure became more stable, leading to a significantly enhanced stability (54.80% and 90.90% relative activity at 70 °C and pH 9.0, respectively) and good reusability (48.92% activity after 5 cycles). This study provides a promising avenue to develop immobilized lipase with high catalytic properties for industry applications.

Structure-directed bioengineering the lid1 of cold-adapted Pseudomonas sp. TB11 esterase to boost catalytic capacity

Structure-guided bioengineering enzymes has been an efficient strategy to obtain biocatalyst with desirable properties. In this study, the cold-adapted esterase from Pseudomonas sp. (CPE) was optimized through bioinformatic-based structured-guided bioengineering on lid1 region. Substitutions of non-conserved Q55 led to noticeable increase in hydrolysis without sacrificing enzyme thermostability, activating effects of Ca2+ and organic solvents. Compared to the wild type, both of Q55V and Q55N among the constructed variants exhibited about a 2.0-fold and 6.5-fold higher hydrolytic activity toward short-chain and long-chain substrates, respectively. In contrast, lid swapping with the lid of Thermomyces lanuginosus lipase reduced the activity and thermostability of CPE. Catalytic kinetics revealed that substitution of Q55 with Y, V, N and R enhanced the substrate affinity of CPE. Hydrolysis by Q55V remarkedly enriched the characteristic flavor components of single cream. The study sheds light on structure-guided bioengineering of lid tailoring cold-adapted esterases with desired catalytic performance to meet the demand from biotechnological applications.

Alternative protein encapsulation with MOFs: overcoming the elusive mineralization of HKUST-1 in water

Protein encapsulation by in situ formation of MOFs is a valuable strategy to immobilise and protect these bioentities. However the required biocompatible conditions limits the scope of MOFs under investigation, particularly in the case of hydrolytically unstable MOFs such as HKUST-1. We report alternative synthetic procedures to obtain protein@HKUST-1 biocomposites from related Cu-BTC dense biocomposites. pH dependent dense phase precursors are first obtained and their transformations into HKUST-1 are characterized. Encapsulation efficiency is affected by the protein's nature, and can be modulated by the sequential or simultaneous addition of MOF precursors.

Enhanced activity of Candida antarctica lipase B in cholinium aminoate ionic liquids: a combined experimental and computational analysis

As a class of ionic liquids with higher biocompatibility, cholinium aminoates ([Cho][AA]) hold potential as solvation media for enzymatic bioprocessing. Herein, solvation effect of [Cho][AA] on structural stability and enzymatic activity of Candida antarctica lipase B (CALB) was evaluated using experimental and computational approaches. Influence of [Cho][AA] on CALB stability was investigated using amino acid anions ([AA]-) with varying hydrophobicity levels. Choline phenylalaninate ([Cho][Phe]) resulted in 109.1% and 110.4% of relative CALB activity to buffer medium at 25 °C and 50 °C, respectively. Simulation results revealed the improvement of CALB's enzymatic activities by [AA]- with a strong hydrophobic character. Shielding of CALB from water molecules by [AA]- was observed. The level of CALB activity was governed by accumulation level of [AA]- at CALB's first hydration layer. The stronger interaction between His224 and Asp187 was postulated to be driven by [Cho][AA], resulting in the activity enhancement of CALB. The slight improvement of CALB activity in 0.05 M [Cho][Phe] at 50 °C could be due to the larger size of entrance to the catalytic site and the stronger interaction between the catalytic residues. The promising effect of [Cho][Phe] on CALB activation may stimulate research efforts in designing a 'fully green' bioreaction for various industrial applications.Communicated by Ramaswamy H. Sarma.

Effects of kosmotropic, chaotropic, and neutral salts on Candida antarctica B lipase: An analysis of the secondary structure and its hydrolytic activity on triglycerides

The effects of different concentrations of Hofmeister salts on the hydrolytic activity on triglycerides and the secondary structure of lipase B from Candida antarctica (CALB) were investigated. Structural changes after short- and long-time incubation at high salt concentrations were determined using circular dichroism (CD), fluorescence, and RMSD-RMSF simulations. At 5.2 M NaCl, the hydrolytic activity of CALB on tributyrin (TC4) and trioctanoin (TC8) was enhanced by 1.5 (from 817 ± 3.9 to 1228 ± 4.3 U/mg)- and 8.7 (from 25 ± 0.3 to 218 ± 2.3 U/mg)-folds compared with 0.15 M NaCl, respectively at pH 7.0 and 40 °C. An activity activation was seen with other salts tested; however, long-time incubation (24 h) did not result in retention of the activation effect for any of the salts tested. Secondary structure CD and fluorescence spectra showed that long-time incubation with NaCl, KCl, and CsCl provokes a compact structure without loss of native conformation, whereas chaotropic LiCl and CaCl2 induced an increase in the α-helical content, and kosmotropic Na2SO4 provoked a molten globule state with rich β-sheet content. The RMSD-RMSF simulation agreed with the CD analysis, highlighting a principal salt-induced effect at the α-helix 5 region, promoting two different conformational states (open and closed) depending on the type and concentration of salt. Lastly, an increase in the interfacial tension occurred when high salt concentrations were added to the reaction media, affecting the catalytic properties. The results indicate that high-salt environments, such as 2-5.2 M NaCl, can be used to increase the lipolytic activity of CALB on TC4 and TC8.

Immobilization of Candida antarctica lipase B on ILs modified CNTs with different chain lengths: Regulation of substrate tunnel "Leucine gating"

Ionic liquids (ILs) have been widely used as chemical modifiers to modify the carriers and thus improve the efficiency, activity and stability of the enzymes. However, as thousands of ILs have been found up to date, it's a huge work for screening and designing suitable ILs for immobilization of enzymes. Moreover, the mechanism of improving enzymes catalytic performance is still remain ambiguous. Thus, this study investigated the impact of ILs with different chain lengths on the enzymatic properties of Candida antarctica lipase B (CALB). Molecular dynamics simulations were employed to examine the interaction between ILs modified CNTs and CALB, as well as their effects on CALB's structure. The results revealed that ILs with different chain lengths significantly influenced the absorption orientation of CALB. Tunnel analysis identified a key role for Leu278 in regulating the open or closed state of Tunnel 2 during CALB's catalytic cycle. The weak interaction analysis demonstrated that ILs with suitable chain lengths provided spatial freedom and formed strong interactions with CNTs and ILs (vdW and hbond). This led to a conformational flip of Leu278, stabilizing the open state of Tunnel 2 and improving the activity and stability of immobilized CALB. This study provides novel insights into the design of new green modifiers to modulate carrier performance and obtain immobilized enzymes with better performance, and establishes a theoretical basis for the design and selection of modifiers for ILs in future work.

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.

Effect of Oil Polarity on the Protein Adsorption at Oil-Water Interfaces

Protein adsorption at oil-water interfaces has received much attention in applications of food emulsion and biocatalysis. The protein activity is influenced by the protein orientation and conformation. The oil polarity is expected to influence the orientation and conformation of adsorbed proteins by modulating intermolecular interactions. Hence, it is possible to tune the protein emulsion stability and activity by varying the oil polarity. Martini v3.0-based coarse-grained molecular dynamics (CGMD) simulations were employed to investigate the effect of oil polarity on the orientation and conformation of hydrophobin (HFBI) and Candida antarctica lipase B (CALB) adsorbed at triolein-water, hexadecane-water, and octanol-water interfaces for the first time. The protein adsorption orientation was predicted through the hydrophobic dipole, indicating that protein adsorption exists in preferred orientations at hydrophobic oil interfaces. The conformation of the adsorbed HFBI is well conserved, whereas relatively larger conformational changes occur during the CALB adsorption as the oil hydrophobicity increases. Comparisons on the adsorption interaction energy of proteins with oils confirm the relationship between the oil polarity and the interaction strength of proteins with oils. In addition, CGMD simulations allow longer time scale simulations of the behaviors of protein adsorption at oil-water interfaces.

The Conformational Transitions and Dynamics of Burkholderia cepacia Lipase Regulated by Water-Oil Interfaces

Structural dynamics and conformational transitions are crucial for the activities of enzymes. As one of the most widely used industrial biocatalysts, lipase could be activated by the water-oil interfaces. The interface activations were believed to be dominated by the close-to-open transitions of the lid subdomains. However, the detailed mechanism and the roles of structure transitions are still under debate. In this study, the dynamic structures and conformational transitions of Burkholderia cepacia lipase (LipA) were investigated by combining all-atom molecular dynamics simulations, enhanced sampling simulation, and spectrophotometric assay experiments. The conformational transitions between the lid-open and lid-closed states of LipA in aqueous solution are directly observed by the computational simulation methods. The interactions between the hydrophobic residues on the two lid-subdomains are the driven forces for the LipA closing. Meanwhile, the hydrophobic environment provided by the oil interfaces would separate the interactions between the lid-subdomains and promote the structure opening of LipA. Moreover, our studies demonstrate the opening of the lids structure is insufficient to initiate the interfacial activation, providing explanations for the inability of interfacial activation of many lipases with lid structures.

Heterologous expression, purification, and characterization of a recombinant Cordyceps militaris lipase from Candida rugosa-like family in Pichia pastoris

Multiple sequence alignments of three lipase isoforms from the filamentous fungus, Cordyceps militaris, have revealed that the deduced protein from their common sequence belongs to the Candida rugosa lipase-like group. To express the protein in its active form, recombinant lipase from C. militaris (rCML) was extra cellularly expressed in Pichia pastoris X-33 after removing its signal peptide. Purified rCML was a stable monomeric protein with a molecular mass of 90 kDa, and was highly N-mannosylated compared to the native protein (69 kDa). The catalytic efficiency (k_cat/K_m) of rCML was greater than the native protein (1244.35 ± 50.88 and 1067.17 ± 29.07 mM^-1·min^-1, respectively), yet they had similar optimal pH values and temperatures (40 °C and pH 7.0-7.5), and showed preferences for Tween esters and short-chain triacylglycerols. Despite its monomeric conformation, interfacial activation was not observed for rCML, unlike the classical lipases. From the structural model of rCML, the binding pocket of rCML was predicted as a funnel-like structure consisting of a hollow space and an intramolecular tunnel, which is typical of C. rugosa lipase-like lipases. However, a blockage shortened the tunnel to 12-15 Å, which endows strict short-chain selectivity towards triacylglycerols and a perfect match for tricaproin (C6:0). The limited depth of the tunnel may enable accommodation of triacylglycerols with medium-to-long-chain fatty acids, which differentiates rCML from other C. rugosa lipase-like lipases with broad substrate specificities.

Pharmacological Activities and Chemical Stability of Natural and Enzymatically Acylated Anthocyanins: A Comparative Review

Anthocyanins (ANCs) are naturally occurring water-soluble pigments responsible for conferring red, blue, and purple colors to fruits, vegetables, flowers, and grains. Due to their chemical structure, they are highly susceptible to degradation by external factors, such as pH, light, temperature, and oxygen. Naturally acylated anthocyanins have proven to be more stable in response to external factors and exhibit superior biological effects as compared with their non-acylated analogues. Therefore, synthetic acylation represents a viable alternative to make the application of these compounds more suitable for use. Enzyme-mediated synthetic acylation produces derivatives that are highly similar to those obtained through the natural acylation process, with the main difference between these two pathways being the catalytic site of the enzymes involved in the synthesis; acyltransferases catalyze natural acylation, while lipases catalyze synthetic acylation. In both cases, their active sites perform the addition of carbon chains to the hydroxyl groups of anthocyanin glycosyl moieties. Currently, there is no comparative information regarding natural and enzymatically acylated anthocyanins. In this sense, the aim of this review is to compare natural and enzyme-mediated synthetic acylated anthocyanins in terms of chemical stability and pharmacological activity with a focus on inflammation and diabetes.

Climatic Chamber Stability Tests of Lipase-Catalytic Octyl-Sepharose Systems

The application of the climatic chamber presented in this paper to assess the storage stability of immobilized lipases is a new approach characterized by the potential of unifying the study conditions of biocatalysts created in various laboratories. The data achieved from storing lipases in the climatic chambers may be crucial for the chemical and pharmaceutical industry. Our paper describes the developed protocols for immobilization via interfacial activation of lipase B from Candida antarctica (CALB) and lipase OF from Candida rugosa (CRL-OF) on the Octyl-Sepharose CL-4B support. Optimization included buffers with different pH values of 4–9 and a wide range of ionic strength from 5 mM to 700 mM. It has been shown that the optimal medium for the CALB immobilization process on the tested support is a citrate buffer at pH 4 and high ionic strength of 500 mM. Implementing new optimal procedures enabled the hyperactivation of immobilized CALB (recovery activity 116.10 ± 1.70%) under the applicable reaction conditions using olive oil as a substrate. Importantly, CALB storage stability tests performed in a climatic chamber under drastic temperature and humidity conditions proved good stability of the developed biocatalyst (residual activity 218 ± 7.3% of dry form, after 7 days). At the same time, the low storage stability of CRL OF in a climatic chamber was demonstrated. It should be emphasized that the use of a climatic chamber to test the storage stability of a dry form of the studied lipases immobilized on Octyl-Sepharose CL-4B is, to our knowledge, described for the first time in the literature.

Improved catalytic properties of Candida antarctica lipase B immobilized on cetyl chloroformate-modified cellulose nanocrystals

The catalytic activity of Candida antarctica lipase B (CALB) immobilized on modified cellulose nanocrystals (CNC) with different hydrophobicity was investigated using experimental and theoretical approaches. Firstly, the modified CNC were characterized by multi-spectroscopic methods, water contact angle, scanning electron microscopy and thermogravimetric analysis. Moderately hydrophobic CNC were found to be an optimal support for CALB immobilization. Secondly, model systems contained a CALB molecule and different numbers of modified CNC molecules (CALB@3CNC-C16, CALB@10CNC-C16 and CALB@15CNC-C16) were prepared for molecular dynamics (MD) simulation. Root-mean-square fluctuation values (0.61-2.61 Å) of lid region were relatively high in CALB@10CNC-C16, indicating that modified CNC with moderate hydrophobicity favored forming a lid-open conformation of CALB. Finally, the esterification of oleic acid catalyzed by the immobilized CALB showed higher conversion (54.68 %) than free CALB (12.98 %). Insights into modified CNC with tunable properties provided by this study may be a potential support for improving the catalytic performance of lipases.

The High ‘Lipolytic Jump’ of Immobilized Amano A Lipase from Aspergillus niger in Developed ‘ESS Catalytic Triangles’ Containing Natural Origin Substrates

Lipase Amano A from Aspergillus niger (AA-ANL) is among the most commonly applied enzymes in biocatalysis processes, making it a significant scientific subject in the pharmaceutical and medical disciplines. In this study, we investigated the lipolytic activity of AA-ANL immobilized onto polyacrylic support IB-150A in 23 oils of natural origin containing various amounts of polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs). The created systems were expressed as an ‘ESS catalytic triangle’. A distinct ‘jump’ (up to 2400%) of lipolytic activity of immobilized AA-ANL compared to free lipase and hyperactivation in mostly tested substrates was observed. There was a ‘cutoff limit’ in a quantitative mutual ratio of ω-PUFAs/MUFAs, for which there was an increase or decrease in the activity of the immobilized AA-ANL. In addition, we observed the beneficial effect of immobilization using three polyacrylic supports (IB-150A, IB-D152, and IB-EC1) characterized by different intramolecular interactions. The developed substrate systems demonstrated considerable hyperactivation of immobilized AA-ANL. Moreover, a ‘lipolytic jump’ in the full range of tested temperature and pH was also observed. The considerable activity of AA-ANL-IB-150A after four reuse cycles was demonstrated. On the other hand, we observed an essential decrease in stability of immobilized lipase after 168 h of storage in a climate chamber. The tested kinetic profile of immobilized AA-ANL confirmed the increased affinity to the substrate relative to lipase in the free form.

Cutinase ACut2 from Blastobotrysraffinosifermentans for the Selective Desymmetrization of the Symmetric Diester Diethyl Adipate to the Monoester Monoethyl Adipate

Monoethyl adipate (MEA) is a highly valuable monoester for activating resistance mechanisms and improving protective effects in pathogen-attacked plants. The cutinase ACut2 from the non-conventional yeast Blastobotrys (Arxula) raffinosifermentans (adeninivorans) was used for its synthesis by the desymmetrization of dicarboxylic acid diester diethyl adipate (DEA). Up to 78% MEA with 19% diacid adipic acid (AA) as by-product could be synthesized by the unpurified ACut2 culture supernatant from the B. raffinosifermentans overexpression strain. By adjusting pH and enzyme concentration, the selectivity of the free ACut2 culture supernatant was increased, yielding 95% MEA with 5% AA. Selectivity of the carrier immobilized ACut2 culture supernatant was also improved by pH adjustment during immobilization, as well as carrier enzyme loading, ultimately yielding 93% MEA with an even lower AA concentration of 3-4%. Thus, optimizations enabled the selective hydrolysis of DEA into MEA with only a minor AA impurity. In the up-scaling, a maximum of 98% chemical and 87.8% isolated MEA yield were obtained by the adsorbed enzyme preparation with a space time yield of 2.6 g L-1 h-1. The high monoester yields establish the ACut2-catalyzed biosynthesis as an alternative to existing methods.

Green synthesis of polydopamine functionalized magnetic mesoporous biochar for lipase immobilization and its application in interesterification for novel structured lipids production

In this study, the polydopamine functionalized magnetic mesoporous biochar (MPCB-DA) was prepared for immobilization of Bacillus licheniformis lipase via covalent immobilization. Under optimized immobilization conditions, the maximum immobilization yield, efficiency and immobilized lipase amount were found to be 45%, 54% and 36.9 mg/g, respectively. The immobilized lipase, MPCB-DA-Lipase showed good thermal stability and alkali resistance. The MPCB-DA-Lipase retained 56% initial activity after 10 reuse cycles, with more than 85% relative activity after 70 days' storage at 4 or 25 °C. The MPCB-DA-Lipase was efficiently applied in the interesterification of Cinnamomum camphora seed kernel oil and perilla seed oil, with maximum interesterification efficiency of 46%. The produced structured lipids belong to the S₂U and U₂S triacylglycerols, a novel medium-and long-chain triacylglycerol. These results demonstrated that the MPCB-DA-Lipase may be used as an efficient biocatalyst in lipid processing applications of food industries.

Rebuilding the lid region from conformational and dynamic features to engineering applications of lipase in foods: Current status and future prospects

The applications of lipases in esterification, amidation, and transesterification have broadened their potential in the production of fine compounds with high cumulative values. Mostly, the catalytic triad of lipases is covered by either one or two mobile peptides called the "lid" that control the substrate channel to the catalytic center. The lid holds unique conformational allostery via interfacial activation to regulate the dynamics and catalytic functions of lipases, thereby highlighting its importance in redesigning these enzymes for industrial applications. The structural characteristic of lipase, the dynamics of lids, and the roles of lid in lipase catalysis were summarized, providing opportunities for rebuilding lid region by biotechniques (e.g., metagenomic technology and protein engineering) and enzyme immobilization. The review focused on the advantages and disadvantages of strategies rebuilding the lid region. The main shortcomings of biotechnologies on lid rebuilding were discussed such as negative effects on lipase (e.g., a decrease of activity). Additionally, the main shortcomings (e.g., enzyme desorption at high temperatre) in immobilization on hydrophobic supports via interfacial action were presented. Solutions to the mentioned problems were proposed by combinations of computational design with biotechnologies, and improvements of lipase immobilization (e.g., immobilization protocols and support design). Finally, the review provides future perspectives about designing hyperfunctional lipases as biocatalysts in the food industry based on lid conformation and dynamics.

Enzymatic Poly(octamethylene suberate) Synthesis by a Two-Step Polymerization Method Based on the New Greener Polymer-5B Technology

Here, we report a new two-step enzymatic polymerization strategy for the synthesis of poly(octamethylene suberate) (POS) using an immobilized Pseudozyma antarctica lipase B (IMM-PBLI). The strategy overcomes the lack of enzymatic POS synthesis in solvent-free systems and increases the final polymer molecular weight. In the first step, the direct polycondensation of suberic acid and 1,8-octanediol was catalyzed by IMM-PBLI at 45 °C, leading to the production of prepolymers with molecular weights (MWs) of 2800, 3400, and 4900 g mol−1 after 8 h in miniemulsion, water, and an organic solvent (cyclohexane: tetrahydrofuran 5:1 v/v), respectively. In the second polymerization step, wet prepolymers were incubated at 60 or 80 °C, at atmospheric pressure, in the presence of IMM-PBLI, and without stirring. The final POS polymers showed a significant increase in MW to 5000, 5800, and 19,800 g mol−1 (previously synthesized in miniemulsion, water, or organic solvent, respectively). FTIR analysis of the final polymers confirmed the successful POS synthesis and a high degree of monomer conversion. This innovative two-step polymerization strategy opens up a new opportunity for implementing greener and more environmentally friendly processes for synthesizing biodegradable polyesters.

Deep eutectic solvents – a new additive in the encapsulation of lipase B from Candida antarctica: biocatalytic applications

An efficient, active and stable biocatalyst was prepared by sol–gel CaL-B encapsulation in the presence of a choline–fructose DES, and is able to transform efficiently ten alcohols relevant for various industries.

Activation and Stabilization of Lipase B from Candida antarctica by Immobilization on Polymer Brushes with Optimized Surface Structure

A reusable support system for the immobilization of lipases is developed using hybrid polymer-inorganic core shell nanoparticles. The biocatalyst core consists of a silica nanoparticle. PMMA is grafted from the nanoparticle as polymer brush via ARGET ATRP (activator regenerated by electron transfer atom transfer radical polymerization), which allows defining the surface properties by chemical synthesis conditions. Lipase B from Candida antarctica is immobilized on the hybrid particles. The activity and stability of the biocatalyst are analyzed by spectroscopic activity analysis. It is shown that the hydrophobic PMMA brushes provide an activating surface for the lipase giving a higher specific activity than the enzyme in solution. Varying the surface structure from disordered to ordered polymer brushes reveals that the reusability of the biocatalyst is more effectively optimized by the surface structure than by the introduction of crosslinking with glutaraldehyde (GDA). The developed immobilization system is highly suitable for biocatalysis in non-native media which is shown by a transesterification assay in isopropyl alcohol and an esterification reaction in n-heptane.

Capillary electrophoresis for enzyme-based studies: Applications to lipases and kinases

Capillary electrophoresis (CE) is a powerful technique continuously expanding into new application fields. One of these applications involves the study of enzymes, their catalytic activities and the alteration of this activity by specific ligands. In this review, two model enzymes, lipases and kinases, will be used since they differ substantially in their modes of action, reaction requirements and applications making them perfect subjects to demonstrate the advantages and limitations of CE-based enzymatic assays. Indeed, the ability to run CE in various operation modes and hyphenation to different detectors is essential for lipase-based studies. Additionally, the low sample consumption provided by CE promotes it as a promising technique to assay human and viral nucleoside kinases. Undeniably, these are rarely commercially available enzymes and must be frequently produced in the laboratory, a process which requires special sets of skills. CE-based lipase and kinase reactions can be performed outside the capillary (pre-capillary) where the reactants are mixed in a vial prior to their separation or, inside the capillary (in-capillary) where the reactants are mixed before the electrophoretic analysis. These enzyme-based applications of CE will be compared to those of liquid chromatography-based applications in terms of advantages and limitations. Binding assays based on affinity CE and the compelling microscale thermophoresis (MST) will be briefly presented as they allow a broad understanding of the molecular mechanism behind ligand binding and of the resulting modulation in activity.

Effect of Triton X-100 on the Activity and Selectivity of Lipase Immobilized on Chemically Reduced Graphene Oxides

The effect of support hydrophobicity on lipase activity and substrate selectivity was investigated with and without Triton X-100 (TX-100). Lipases from Thermomyces lanuginosa (TL) and Alcaligenes sp. (QLM) were immobilized on graphene oxide (GO) and a range of chemically reduced graphene oxides (CRGOs) with different levels of surface hydrophobicity. Activity assays using 4-hydroxy-N-propyl-1,8-naphthalimide (NAP) esters of varying chain lengths (NAP-butyrate (NAP-B), NAP-octanoate (NAP-O), and NAP-palmitate (NAP-P)) showed that the activity of immobilized QLM and TL decreased by more than 60% on GO and 80% on CRGO (2 h), with activity decreasing further as surface hydrophobicity of the CRGOs increased. Across the hydrophobicity range of GO/CRGOs, the substrate selectivity of QLM shifted from more readily hydrolyzing NAP-P to NAP-B, while TL retained its substrate selectivity for NAP-O. Lipase TL was also shown to desorb from GO and 2 h CRGO when mixed with NAP-O and NAP-P, whereas QLM did not. Circular dichroism analyses of the lipase α-helix content correlate to the observed activity data, with decreases in the α-helical content (40% in TL and 20% in QLM relative to free lipase) consistent with decreases in activity after immobilization on GO. α-Helical content decreased even further as the surface hydrophobicity of CRGOs increased. Attenuated total reflectance-Fourier transform infrared spectroscopy also showed significant changes to the lipase secondary structure upon immobilization. The addition of TX-100 into the activity assay modified the substrate selectivity of immobilized QLM, improving the activity against NAP-O (90%) and NAP-P (67%) compared to the activity measured without TX-100. It was shown that TX-100 primarily affected the activity of QLM by interacting with the ester substrate and the lipase itself. This study provides an improved understanding of how support hydrophobicity and the presence of TX-100 can affect activity/selectivity of lipases immobilized on hydrophobic supports.

Oxidation of 2,5-diformfylfuran to 2,5-furandicarboxylic acid catalyzed by Candida antarctica Lipase B immobilized in a cyclodextrin-templated mesoporous silica. The critical role of pore characteristics on the catalytic performance

HYPOTHESIS

Porous silica has been extensively used as suitable carrier for the immobilization of various enzymes. Randomly Methylated β-Cyclodextrin (RaMeβCD) has surface active properties and very high solubility in water and could therefore be used as template in the fabrication of silica particles with tunable pore size.

EXPERIMENTS

Silica particles were prepared by sol-gel process in alkaline medium with and without use of RaMeβCD. Lipase Bfrom Candida antarctica (CALB) was either incorporated within the pores of RaMeβCD-derived support or covalently attached on the surface of CD-free silica particles and its catalytic performance was assayed in the oxidation of 2,5-diformylfuran (DFF) to 2,5-furandicarboxylic acid (FDCA). Enzymatic reactors were characterized by N₂-adsorption analysis, small angle XRD, TG/DSC experiments, ATR-FTIR spectroscopy, HR-TEM and LSCM, while reaction products were determined based on ¹H NMR spectroscopy combined with HPLC.

FINDINGS

Results showed that the use of RaMeβCD as structure directing agent led to mesoporous silica composed of uniform 8 nm-sized particles with 11 nm-sized mesopores compatible with the dimensions of CALB (3.0 nm × 4.0 nm × 5.0 nm). Incorporation of CALB within the pores of RaMeβCD-derived silica caused almost a two-fold increase in specific activity after 7 h at 40 °C when compared to lipase immobilized on the surface of CD-free silica particles (33.2 μmol g^-1 min^-1vs. 14.4 μmol g^-1 min^-1). Moreover, the RaMeβCD-derived biocatalyst demonstrated enhanced operational stability during the recycling experiments, retaining more than 90% of its initial activity after five 24 h-reaction cycles. These findings open up new avenues for future research on the use of cyclodextrins in the development of enzyme-based nanoreactors.

Biodegradable Polyester Synthesis in Renewed Aqueous Polycondensation Media: The Core of the New Greener Polymer-5B Technology

An innovative enzymatic polycondensation of dicarboxylic acids and dialcohols in aqueous polymerization media using free and immobilized lipases was developed. Various parameters (type of lipases, temperature, pH, stirring type and rate, and monomer carbon chain length) of the polycondensation in an oil-in-water (o/w) miniemulsion (>80% in water) were evaluated. The best results for polycondensation were achieved with an equimolar monomer concentration (0.5 M) of octanedioic acid and 1,8-octanediol in the miniemulsion and water, both at initial pH 5.0 with immobilized Pseudozyma antarctica lipase B (PBLI). The synthesized poly(octamethylene suberate) (POS) in the miniemulsion is characterized by a molecular weight of 7800 g mol−1 and a conversion of 98% at 45 °C after 48 h of polycondensation in batch operation mode. A comparative study of polycondensation using different operation modes (batch and fed-batch), stirring type, and biocatalyst reutilization in the miniemulsion, water, and an organic solvent (cyclohexane:tetrahydrofuran 5:1 v/v) was performed. Regarding the polymer molecular weight and conversion (%), batch operation mode was more appropriate for the synthesis of POS in the miniemulsion and water, and fed-batch operation mode showed better results for polycondensation in the organic solvent. The miniemulsion and water used as polymerization media showed promising potential for enzymatic polycondensation since they presented no enzyme inhibition for high monomer concentrations and excellent POS synthesis reproducibility. The PBLI biocatalyst presented high reutilization capability over seven cycles (conversion > 90%) and high stability equivalent to 72 h at 60 °C on polycondensation in the miniemulsion and water. The benefits of polycondensation in aqueous media using an o/w miniemulsion or water are the origin of the new concept strategy of the green process with a green product that constitutes the core of the new greener polymer-5B technology.

Biochemical and Structural Characterization of a novel thermophilic esterase EstD11 provide catalytic insights for the HSL family

A novel esterase, EstD11, has been discovered in a hot spring metagenomic library. It is a thermophilic and thermostable esterase with an optimum temperature of 60°C. A detailed substrate preference analysis of EstD11 was done using a library of chromogenic ester substrate that revealed the broad substrate specificity of EstD11 with significant measurable activity against 16 substrates with varied chain length, steric hindrance, aromaticity and flexibility of the linker between the carboxyl and the alcohol moiety of the ester. The tridimensional structures of EstD11 and the inactive mutant have been determined at atomic resolutions. Structural and bioinformatic analysis, confirm that EstD11 belongs to the family IV, the hormone-sensitive lipase (HSL) family, from the α/β-hydrolase superfamily. The canonical α/β-hydrolase domain is completed by a cap domain, composed by two subdomains that can unmask of the active site to allow the substrate to enter. Eight crystallographic complexes were solved with different substrates and reaction products that allowed identification of the hot-spots in the active site underlying the specificity of the protein. Crystallization and/or incubation of EstD11 at high temperature provided unique information on cap dynamics and a first glimpse of enzymatic activity in vivo. Very interestingly, we have discovered a unique Met zipper lining the active site and the cap domains that could be essential in pivotal aspects as thermo-stability and substrate promiscuity in EstD11.

Enzyme/Nanocopper Hybrid Nanozymes: Modulating Enzyme-like Activity by the Protein Structure for Biosensing and Tumor Catalytic Therapy

Artificial enzymes with modulated enzyme-mimicking activities of natural systems represent a challenge in catalytic applications. Here, we show the creation of artificial Cu metalloenzymes based on the generation of Cu nanoparticles in an enzyme matrix. Different enzymes were used, and the structural differences between the enzymes especially influenced the controlled the size of the nanoparticles and the environment that surrounds them. Herein, we demonstrated that the oxidase-like catalytic activity of these copper nanozymes was rationally modulated by enzyme used as a scaffold, with a special role in the nanoparticle size and their environment. In this sense, these nanocopper hybrids have confirmed the ability to mimic a unique enzymatic activity completely different from the natural activity of the enzyme used as a scaffold, such as tyrosinase-like activity or as Fenton catalyst, which has extremely higher stability than natural mushroom tyrosinase. More interestingly, the oxidoreductase-like activity of nanocopper hybrids was cooperatively modulated with the synergistic effect between the enzyme and the nanoparticles improving the catalase activity (no peroxidase activity). Additionally, a novel dual (metallic and enzymatic activity) of the nanozyme made the highly improved catechol-like activity interesting for the design of 3,4-dihydroxy-l-phenylalanine (l-DOPA) biosensor for detection of tyrosinase. These hybrids also showed cytotoxic activity against different tumor cells, interesting in biocatalytic tumor therapy.

Combining technology with liquid-formulated lipases for in-spec biodiesel production

Enzymatic biodiesel production has been at the forefront of biofuels research in recent decades because of the significant environmental advantages it offers, while having the potential to be as effective as conventional chemically catalyzed biodiesel production. However, the higher capital cost, longer reaction time, and sensitivity of enzyme processes have restricted their widespread industrial adoption so far. It is also posited that the lack of research to bring the biodiesel product into final specification has scuppered industrial confidence in the viability of the enzymatic process. Furthermore, the vast majority of literature has focused on the development of immobilized enzyme processes, which seem too costly (and risky) to be used industrially. There has been little focus on liquid lipase formulations such as the Eversa Transform 2.0, which is in fact already used commercially for triglyceride transesterification. It is the objective of this review to highlight new research that focuses on bringing enzymatically produced biodiesel into specification via a liquid lipase polishing process, and the process considerations that come with it.

Immobilized Phospholipase A1-Catalyzed Preparation of l-α-Glycerylphosphorylcholine from Phosphatidylcholine

This study sought to prepare a cognitive enhancer l-α-glycerylphosphorylcholine (l-α-GPC) using an immobilized Lecitase Ultra (LU, phospholipase A₁) to catalyze the hydrolysis of soy phosphatidylcholine (PC). Immobilization of LU on Lewatit VP OC 1600 provided the highest fixation level (83.1 g/100 g) and greatest catalytic activity achieving 100 g/100 g l-α-GPC within 20 h and was therefore selected as the optimal system for biocatalysis. Immobilization of LU increased its positional specificity compared to free LU, as shown by a decrease in the production of the phosphocholine byproduct. Under the optimal conditions determined by response surface methodology, PC was completely hydrolyzed to l-α-GPC and required a simple purification via phase separation of the biphasic media to obtain a yield of ∼26.4 g l-α-GPC from 100 g PC, with a purity of 98.5 g/100 g. Our findings suggest a possibility of using the immobilized LU as a new biocatalyst for the l-α-GPC production.

Immobilisation of Candida rugosa lipase on a highly hydrophobic support: A stable immobilised lipase suitable for non-aqueous synthesis

Lipase from Candida rugosa (CrL) was immobilised on highly hydrophobic, octadecyl methacrylate resin (Lifetech™ ECR8806M) via interfacial adsorption. The aim was to produce a stable biocatalyst suitable for use in a range of lipid-modifying reactions. Immobilisation was carried out in 10 mM phosphate buffer (pH 6.0) over 24 h at 21 °C. High protein binding of 58.7 ± 4.9 mg/g dry support accounted for ∼53 % of the applied protein. The activity recovery against tributyrin was 74.0 ± 1.1 %. The specific activity of immobilised CrL against tributyrin was considerably higher than that of Novozym® 435, at 1.79 ± 0.05 and 1.08 ± 0.04 U/mg bound protein, respectively. Incubation with high concentrations (10 % w/v) of both Triton X-100 and SDS resulted in only a small reduction in immobilised lipase activity. Solvent-free synthesis of glycerides by the FFA-saturated immobilised CrL was successful over 6 reaction cycles, with no apparent loss of activity.

Chemoenzymatic Synthesis of the New 3-((2,3-Diacetoxypropanoyl)oxy)propane-1,2-diyl Diacetate Using Immobilized Lipase B from Candida antarctica and Pyridinium Chlorochromate as an Oxidizing Agent

To exploit the hydrolytic activity and high selectivity of immobilized lipase B from Candida antarctica on octyl agarose (CALB-OC) in the hydrolysis of triacetin and also to produce new value-added compounds from glycerol, this work describes a chemoenzymatic methodology for the synthesis of the new dimeric glycerol ester 3-((2,3-diacetoxypropanoyl)oxy)propane-1,2-diyl diacetate. According to this approach, triacetin was regioselectively hydrolyzed to 1,2-diacetin with CALB-OC. The diglyceride product was subsequently oxidized with pyridinium chlorochromate (PCC) and a dimeric ester was isolated as the only product. It was found that the medium acidity during the PCC treatment and a high 1,2-diacetin concentration favored the formation of the ester. The synthesized compounds were characterized using IR, MS, HR-MS, and NMR techniques. The obtained dimeric ester was evaluated at 100 ppm against seven bacterial strains and two Candida species to identify its antimicrobial activity. The compound has no inhibitory activity against the bacterial strains used but decreased C. albicans and C. parapsilosis growth by 49% and 68%, respectively. Hemolytic activity was evaluated, and the results obtained support the use of the dimeric ester to control C. albicans and C. parapsilosis growth in non-intravenous applications because the compound shows hemolytic activity.

Evaluation of Designed Immobilized Catalytic Systems: Activity Enhancement of Lipase B from Candida antarctica

Immobilized enzymatic catalysts are widely used in the chemical and pharmaceutical industries. As Candida antarctica lipase B (CALB) is one of the more commonly used biocatalysts, we attempted to design an optimal lipase-catalytic system. In order to do that, we investigated the enantioselectivity and lipolytic activity of CALB immobilized on 12 different supports. Immobilization of lipase on IB-D152 allowed us to achieve hyperactivation (178%) in lipolytic activity tests. Moreover, the conversion in enantioselective esterification increased 43-fold, when proceeding with lipase-immobilized on IB-S861. The immobilized form exhibited a constant high catalytic activity in the temperature range of 25 to 55 °C. Additionally, the lipase immobilized on IB-D152 exhibited a higher lipolytic activity in the pH range of 6 to 9 compared with the native form. Interestingly, our investigations showed that IB-S500 and IB-S60S offered a possibility of application in catalysis in both organic and aqueous solvents. A significant link between the reaction media, the substrates, the supports and the lipase was confirmed. In our enzymatic investigations, high-performance liquid chromatography (HPLC) and the titrimetric method, as well as the Bradford method were employed.