Exploring the specific features of interfacial enzymology based on lipase studies

Prospective identification of extracellular triacylglycerol hydrolase with conserved amino acids in Amycolatopsis tolypomycina's high G+C genomic dataset

Extracellular triacylglycerol hydrolases (ETH) play a critical role for microorganisms, acting as essential tools for lipid breakdown and survival in challenging environments. The pursuit of more effective ETH genes and enzymes through evolution holds significant potential for enhancing living conditions. This study employs a proteogenomic approach to identify high G+C ETH in a notable Gram-positive bacterium, Amycolatopsis tolypomycina. Utilizing knowledge from genome and machine learning algorithms, prospective ETH genes/enzymes were identified. Notably, the ETH structural conserved accessibility to solvent clearly indicated the specific sixteen residues (GLY50, PRO93, GLY141, ASP148, GLY151, ASP172, ALA176, GLY195, TYR196, SER197, GLN198, GLY199, GLY200, GLY225, PRO327, ASP336) with no frequency. By pinpointing key residues and understanding their role, this study sets the stage for enhancing ETH performance through computational proteogenomic and contributes to the broader field of enzyme engineering, facilitating the development of more efficient and versatile ETH enzymes tailored to specific industrial or environmental contexts.

Valorization of Chicken Viscera as Natural Raw Material Source: Application to Hydrolysis of Fatty Esters for Sewage Treatment

"Chicken viscera" constitutes very abundant domestic wastes interestingly investigated in the present paper. The efficiency of this crude slaughter co-product of high protein component, as biocatalyst, for the hydrolysis of fatty acid esters was reported and that, without any pre-treatment. The crude chicken intestine powder (CIP) has shown a high reactivity for the hydrolysis of fatty esters. Two biocatalyst preparations were independently explored for the bioresolution of sec-phenyl alkyl carbinol esters: the CIP preparation and the crude chicken intestine acetone powder CIAP preparation. The last one has shown good catalytic activity during the bio-hydrolysis in biphasic medium. Furthermore, the direct hydrolysis of milk fat using CIAP (500 mg) reveals the elimination of fats present in 50 ml of treated milk. These results open up very interesting prospects for the use of this biowaste for the treatment of milk fat.

Investigating Lipase/Stain Interactions: Determining Interfacial Protein Conformation with Surface Spectroscopy

Conventional bulk protein structure determination methods are not suitable for understanding the distinct and diverse interactions of proteins with interfaces. Notably, interfacial activation is a feature common to many lipases involving movement of a helical "lid" region upon contact with a hydrophobic surface to expose the catalytic site. Here we use the surface specificity of vibrational sum frequency generation spectroscopy (VSFG) spectroscopy to directly probe the conformation of Thermomyces lanuginosus lipase (TLL) at hydrophobic interfaces. The TLL-catalyzed reaction at the air/water interface is monitored by VSFG spectroscopy, showing loss of ester carbonyl modes and appearance of carboxylate stretching modes of the fatty acid products. Furthermore, comparison of experimental and calculated VSFG spectra of the amide I band of TLL allows us to discern the subtle structural changes involved with lid-opening at a hydrophobic surface. Finally, we report a likely orientation of this lid-open state, which interacts with the surface through a loop region away from the lid and active site. This experimental framework for probing protein structure and function at interfaces addresses a significant problem in protein science that is not only impeding the design of better enzymes for biotechnology applications but also drug discovery targeting membrane associated proteins.

Developing an in vitro lipolysis model for real-time analysis of drug concentrations during digestion of lipid-based formulations

Understanding the effect of digestion on oral lipid-based drug formulations is a critical step in assessing the impact of the digestive process in the intestine on intraluminal drug concentrations. The classical pH-stat in vitro lipolysis technique has traditionally been applied, however, there is a need to explore the establishment of higher throughput small-scale methods. This study explores the use of alternative lipases with the aim of selecting digestion conditions that permit in-line UV detection for the determination of real-time drug concentrations. A range of immobilised and pre-dissolved lipases were assessed for digestion of lipid-based formulations and compared to digestion with the classical source of lipase, porcine pancreatin. Palatase® 20000 L, a purified liquid lipase, displayed comparable digestion kinetics to porcine pancreatin and drug concentration determined during digestion of a fenofibrate lipid-based formulation were similar between methods. In-line UV analysis using the MicroDISS ProfilerTM demonstrated that drug concentration could be monitored during one hour of dispersion and three hours of digestion for both a medium- and long-chain lipid-based formulations with corresponding results to that obtained from the classical lipolysis method. This method offers opportunities exploring the real-time dynamic drug concentration during dispersion and digestion of lipid-based formulations in a small-scale setup avoiding artifacts as a result of extensive sample preparation.

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

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

Discovery of a non-canonical prototype long-chain monoacylglycerol lipase through a structure-based endogenous reaction intermediate complex

The identification and characterization of enzyme function is largely lacking behind the rapidly increasing availability of large numbers of sequences and associated high-resolution structures. This is often hampered by lack of knowledge on in vivo relevant substrates. Here, we present a case study of a high-resolution structure of an unusual orphan lipase in complex with an endogenous C18 monoacylglycerol ester reaction intermediate from the expression host, which is insoluble under aqueous conditions and thus not accessible for studies in solution. The data allowed its functional characterization as a prototypic long-chain monoacylglycerol lipase, which uses a minimal lid domain to position the substrate through a hydrophobic tunnel directly to the enzyme's active site. Knowledge about the molecular details of the substrate binding site allowed us to modulate the enzymatic activity by adjusting protein/substrate interactions, demonstrating the potential of our findings for future biotechnology applications.

Pancreatic lipase digestion: The forgotten barrier in oral administration of lipid-based delivery systems?

This review highlights the importance of controlling the digestion process of orally administered lipid-based delivery systems (LBDS) and their performance. Oral LBDS are prone to digestion via pancreatic lipase in the small intestine. Rapid or uncontrolled digestion may cause the loss of delivery system integrity, its structural changes, reduced solubilization capacity and physical stability issues. All these events can lead to uncontrolled drug release from the digested LBDS into the gastrointestinal environment, exposing the incorporated drug to precipitation or degradation by luminal proteases. To prevent this, the digestion rate of orally administered LBDS can be estimated by appropriate choice of the formulation type, excipient combinations and their ratios. In addition, in vitro digestion models like pH-stat are useful tools to evaluate the formulation digestion rate. Controlling digestion can be achieved by conventional lipase inhibitors like orlistat, sterically hindering of lipase adsorption on the delivery system surface with polyethylene glycol (PEG) chains, lipase desorption or saturation of the interface with surfactants as well as formulating LBDS with ester-free excipients. Recent in vivo studies demonstrated that digestion inhibition lead to altered pharmacokinetic profiles, where Cmax and Tmax were reduced in spite of same AUC compared to control or even improved oral bioavailability.

Enzyme-responsive biomimetic solid lipid nanoparticles for antibiotic delivery against hyaluronidase-secreting bacteria

In this work, a potent hyaluronidase inhibitor (ascorbyl stearate (AS)) was successfully employed to design vancomycin-loaded solid lipid nanoparticles (VCM-AS-SLNs) with biomimetic and enzyme-responsive features, to enhance the antibacterial efficacy of vancomycin against bacterial-induced sepsis. The VCM-AS-SLNs prepared were biocompatible and had appropriate physicochemical parameters. The VCM-AS-SLNs showed an excellent binding affinity to the bacterial lipase. The in vitro drug release study showed that the release of the loaded vancomycin was significantly accelerated by the bacterial lipase. The in silico simulations and MST studies confirmed the strong binding affinity of AS and VCM-AS-SLNs to bacterial hyaluronidase compared to its natural substrate. This binding superiority indicates that AS and VCM-AS-SLNs could competitively inhibit the effect of hyaluronidase enzyme, and thus block its virulence action. This hypothesis was further confirmed using the hyaluronidase inhibition assay. The in vitro antibacterial studies against sensitive and resistant Staphylococcus aureus revealed that the VCM-AS-SLNs had a 2-fold lower minimum inhibitory concentration, and a 5-fold MRSA biofilm elimination compared to the free vancomycin. Furthermore, the bactericidal-kinetic showed a 100% bacterial clearance rate within 12 hours of treatment with VCM-AS-SLNs, and less than 50 % eradication after 24 hours for the bare VCM. Therefore, the VCM-AS-SLN shows potential as an innovative multi-functional nanosystem for effective and targeted delivery of antibiotics.

Pre-duodenal lipid digestion of emulsions: Relevance, colloidal aspects and mechanistic insight

The digestion of lipids in the human body has several health and nutritional implications. Lipid digestion is an interfacial phenomenon meaning that water-soluble lipases need to first adsorb to the oil-water interface before enzymatic conversions can start. The digestion of lipids mainly occurs on colloidal structures dispersed in water, such as oil-in-water (o/w) emulsions, which can be designed during food formulation/processing or structured during digestion. From a food design perspective, different in vitro studies have demonstrated that the kinetics of lipid digestion can be influenced by emulsion properties. However, most of these studies have been performed with pancreatic enzymes to simulate lipolysis in the small intestine. Only few studies have dealt with lipid digestion in the gastric phase and its subsequent impact on intestinal lipolysis. In this aspect, this review compiles information on the physiological aspects of gastric lipid digestion. In addition, it deals with colloidal and interfacial aspects starting from emulsion design factors and how they evolve during in vitro digestion. Finally, molecular mechanisms describing gastric lipolysis are discussed.

Structural features, temperature adaptation and industrial applications of microbial lipases from psychrophilic, mesophilic and thermophilic origins

Microbial lipases are very prominent biocatalysts because of their ability to catalyze a wide variety of reactions in aqueous and non-aqueous media. Here microbial lipases from different origins (psychrophiles, mesophiles, and thermophiles) have been reviewed. This review emphasizes an update of structural diversity in temperature adaptation and industrial applications, of psychrophilic, mesophilic, and thermophilic lipases. The microbial origins of lipases are logically dynamic, proficient, and also have an extensive range of industrial uses with the manufacturing of altered molecules. It is therefore of interest to understand the molecular mechanisms of adaptation to temperature in occurring lipases. However, lipases from extremophiles (psychrophiles, and thermophiles) are widely used to design biotransformation reactions with higher yields, fewer byproducts, or useful side products and have been predicted to catalyze those reactions also, which otherwise are not possible with the mesophilic lipases. Lipases as a multipurpose biological catalyst have given a favorable vision in meeting the needs of several industries such as biodiesel, foods, and drinks, leather, textile, detergents, pharmaceuticals, and medicals.

κ-Carrageenan Hydrogel as a Matrix for Therapeutic Enzyme Immobilization

During the last few decades, polysaccharide hydrogels attract more and more attention as therapeutic protein delivery systems due to their biocompatibility and the simplicity of the biodegradation of natural polymers. The protein retention by and release from the polysaccharide gel network is regulated by geometry and physical interactions of protein with the matrix. In the present work, we studied the molecular details of interactions between κ-carrageenan and three lipases, namely the lipases from Candida rugosa, Mucor javanicus, and Rhizomucor miehei—which differ in their size and net charge—upon protein immobilization in microparticles of polysaccharide gel. The kinetics of protein release revealed the different capability of κ-carrageenan to retain lipases, which are generally negatively charged; that was shown to be in line with the energy of interactions between polysaccharides and positively charged epitopes on the protein surface. These data create a platform for the novel design of nanocarriers for biomedical probes of enzymatic origin.

Cleaner degreasing of sheepskins by the Yarrowia lipolytica LIP2 lipase as a chemical-free alternative in the leather industry

Conventional degreasing of skins and hides in the leather industry requires high amounts of organic solvents and detergents that cause environmental issues. In this study, the LIP2 lipase from the yeast Yarrowia lipolytica (YLLIP2) was shown to be effective in degreasing sheepskins, thus reducing the amount of harmful chemicals. Using 6 mg of lipase/kg of raw skin, successful degreasing was achieved in only 15 min at pH 8 and 30°C. ToF-SIMS mass spectra of chemically and enzymatically treated sheepskinsare consistent with a selective elimination process for the enzymatic treatment. Comparative SEM microscopy, ATR-FTIR spectroscopy and physicochemical analyses showed better properties of the enzymatically treated leather than those of the chemically treated leather. Effluent physicochemical parameters showed that the enzymatic treatment is a cleaner degreasing operation. Altogether, this work opens new horizons to use the YLLIP2 lipase as a more efficient alternative in the leather industry.

Enzymatic Hydrolysis of Triglycerides at the Water-Oil Interface Studied via Interfacial Rheology Analysis of Lipase Adsorption Layers

The enzymatic hydrolysis of sunflower oil occurs at the water-oil interface. Therefore, the characterization of dynamic interfacial phenomena is essential for understanding the related mechanisms for process optimizations. Most of the available studies for this purpose deal with averaged interfacial properties determined via reaction kinetics and dynamic surface tension measurements. In addition to the classical approach for dynamic surface tension measurements, here, the evolution of the dilational viscoelasticity of the lipase adsorbed layer at the water-oil interface is characterized using profile analysis tensiometry. It is observed that lipase exhibits nonlinear dilational rheology depending on the concentration and age of the adsorbed layer. For reactive water-oil interfaces, the response of the interfacial tension to the sinusoidal area perturbations becomes more asymmetric with time. Surface-active products of the enzymatic hydrolysis of triglycerides render the interface less elastic during compression compared to the expansion path. The lipolysis products can facilitate desorption upon compression while inhibiting adsorption upon expansion of the interface. Lissajous plots provide an insight into how the hysteresis effect leads to different interfacial tensions along the expansion and compression routes. Also, the droplet shape increasingly deviates from a Laplacian shape, demonstrating an irreversible film formation during aging and ongoing hydrolysis reaction, which supports our findings via interfacial elasticity analysis.

A Valuable Product of Microbial Cell Factories: Microbial Lipase

As a powerful factory, microbial cells produce a variety of enzymes, such as lipase. Lipase has a wide range of actions and participates in multiple reactions, and they can catalyze the hydrolysis of triacylglycerol into its component free fatty acids and glycerol backbone. Lipase exists widely in nature, most prominently in plants, animals and microorganisms, among which microorganisms are the most important source of lipase. Microbial lipases have been adapted for numerous industrial applications due to their substrate specificity, heterogeneous patterns of expression and versatility (i.e., capacity to catalyze reactions at the extremes of pH and temperature as well as in the presence of metal ions and organic solvents). Now they have been introduced into applications involving the production and processing of food, pharmaceutics, paper making, detergents, biodiesel fuels, and so on. In this mini-review, we will focus on the most up-to-date research on microbial lipases and their commercial and industrial applications. We will also discuss and predict future applications of these important technologies.

Structure and Function of Pancreatic Lipase-Related Protein 2 and Its Relationship With Pathological States

Pancreatic lipase is critical for the digestion and absorption of dietary fats. The most abundant lipolytic enzymes secreted by the pancreas are pancreatic triglyceride lipase (PTL or PNLIP) and its family members, pancreatic lipase-related protein 1 (PNLIPRP1or PLRP1) and pancreatic lipase-related protein 2 (PNLIPRP2 or PLRP2). Unlike the family’s other members, PNLIPRP2 plays an elemental role in lipid digestion, especially for newborns. Therefore, if genetic factors cause gene mutation, or other factors lead to non-expression, it may have an effect on fat digestion and absorption, on the susceptibility to pancreas and intestinal pathogens. In this review, we will summarize what is known about the structure and function of PNLIPRP2 and the levels of PNLIPRP2 and associated various pathological states.

Phosphatidylserine-specific phospholipase A1: A friend or the devil in disguise

Various human tissues and cells express phospholipase A1 member A (PLA1A), including the liver, lung, prostate gland, and immune cells. The enzyme belongs to the pancreatic lipase family. PLA1A specifically hydrolyzes sn-1 fatty acid of phosphatidylserine (PS) or 1-acyl-lysophosphatidylserine (1-acyl-lysoPS). PS externalized by activated cells or apoptotic cells or extracellular vesicles is a potential source of substrate for the production of unsaturated lysoPS species by PLA1A. Maturation and functions of many immune cells, such as T cells, dendritic cells, macrophages, and mast cells, can be regulated by PLA1A and lysoPS. Several lysoPS receptors, including GPR34, GPR174 and P2Y10, have been identified. High serum levels and high PLA1A expression are associated with autoimmune disorders such as Graves' disease and systemic lupus erythematosus. Increased expression of PLA1A is associated with metastatic melanomas. PLA1A may contribute to cardiometabolic disorders through mediating cholesterol transportation and producing lysoPS. Furthermore, PLA1A is necessary for hepatitis C virus assembly and can play a role in the antivirus innate immune response. This review summarizes recent findings on PLA1A expression, lysoPS and lysoPS receptors in autoimmune disorders, cancers, cardiometabolic disorders, antivirus immune responses, as well as regulations of immune cells.

Modulation of the Biocatalytic Properties of a Novel Lipase from Psychrophilic Serratia sp. (USBA-GBX-513) by Different Immobilization Strategies

In this work, the effect of different immobilization procedures on the properties of a lipase obtained from the extremophilic microorganism Serratia sp. USBA-GBX-513, which was isolated from Paramo soils of Los Nevados National Natural Park (Colombia), is reported. Different Shepharose beads were used: octyl-(OC), octyl-glyoxyl-(OC-GLX), cyanogen bromide (BrCN)-, and Q-Sepharose. The performance of the different immobilized extremophile lipase from Serratia (ESL) was compared with that of the lipase B from Candida antarctica (CALB). In all immobilization tests, hyperactivation of ESL was observed. The highest hyperactivation (10.3) was obtained by immobilization on the OC support. Subsequently, the thermal stability at pH 5, 7, and 9 and the stability in the presence of 50% (v/v) acetonitrile, 50% dioxane, and 50% tetrahydrofuran solvents at pH 7 and 40 °C were evaluated. ESL immobilized on octyl-Sepharose was the most stable biocatalyst at 90 °C and pH 9, while the most stable preparation at pH 5 was ESL immobilized on OC-GLX-Sepharose supports. Finally, in the presence of 50% (v/v) tetrahydrofuran (THF) or dioxane at 40 °C, ESL immobilized on OC-Sepharose was the most stable biocatalyst, while the immobilized preparation of ESL on Q-Sepharose was the most stable one in 40% (v/v) acetonitrile.

Rapid screening of lipase inhibitors in licorice extract by using porcine pancreatic lipase immobilized on Fe3O4 magnetic nanoparticles

Chalcones, a class of natural lipase inhibitors, have received substantial attention from researchers in recent years. Although many kinds of chalcones are typically distributed in G. inflata, there is little literature about the anti-lipase activity of G. inflata extracts (GIEs). In the present study, a ligand fishing strategy for fast screening of lipase inhibitors from GIEs was thus proposed. Porcine pancreatic lipase (PPL) was firstly immobilized on carboxyl modified Fe3O4 magnetic nanoparticles (MNPs) to obtain PPL functionalized MNPs (PPL@MNPs), and then the PPL@MNPs were incubated with a bioactive fraction to fish out the ligands. Eight ligands were obtained and identified as one flavone together with seven chalcones. Licochalcone A, licochalcone D and licochalcone E inhibited pancreatic lipase (PL) with IC50 of 4.9, 3.2 and 5.8 μM, respectively. Meanwhile, investigation of the structure-activity relationship also revealed that isopentenyl and hydroxyl substituents at ring A were essential for the noncovalent inhibitory potency of the chalcones.

Immobilization of phospholipase D on macroporous SiO2/cationic polymer nano-composited support for the highly efficient synthesis of phosphatidylserine

Novel nano-composites were prepared by coating epoxy resin-based cationic polymer in nano-thickness via in-situ curing on the nano-wall of macroporous SiO₂ with pore size of 0.5∼1 μm. By changing the thickness of polymer coating the specific surface area and porosity varied in range of 115∼74 m²/g and 90.4∼83.9 %, respectively. Through ion exchange phospholipase D (PLD, from Streptomyces sp) was efficiently immobilized on the nano-composites as support and the immobilized PLD was applied for the highly efficient synthesis of phosphatidylserine (PS). The loading amount of PLD on the nano-composited support reached to a maximum of 90.2 mg/g_support, 4 times as high as that on the pure macroporous silica. The specific activity of the immobilized PLD reached as high as 16,230 U/g_protein, while that of free PLD was 18,780 U/g_protein. Under a wide range of temperature and pH the stability and activity of the immobilized PLD were greatly improved as compared with the free ones. Under optimized conditions at 45 °C and pH 7.0, the PS yield reached as high as 96.2 % within 40 min. After 28 days storage the immobilized PLD retained 82.2 % of original activity, and after 12 cycling reuses it retained 79.3 % of PS yield, which indicated that the immobilized PLD exhibited good stability.

Multi-Combilipases: Co-Immobilizing Lipases with Very Different Stabilities Combining Immobilization via Interfacial Activation and Ion Exchange. The Reuse of the Most Stable Co-Immobilized Enzymes after Inactivation of the Least Stable Ones

The lipases A and B from Candida antarctica (CALA and CALB), Thermomyces lanuginosus (TLL) or Rhizomucor miehei (RML), and the commercial and artificial phospholipase Lecitase ultra (LEU) may be co-immobilized on octyl agarose beads. However, LEU and RML became almost fully inactivated under conditions where CALA, CALB and TLL retained full activity. This means that, to have a five components co-immobilized combi-lipase, we should discard 3 fully active and immobilized enzymes when the other two enzymes are inactivated. To solve this situation, CALA, CALB and TLL have been co-immobilized on octyl-vinyl sulfone agarose beads, coated with polyethylenimine (PEI) and the least stable enzymes, RML and LEU have been co-immobilized over these immobilized enzymes. The coating with PEI is even favorable for the activity of the immobilized enzymes. It was checked that RML and LEU could be released from the enzyme-PEI coated biocatalyst, although this also produced some release of the PEI. That way, a protocol was developed to co-immobilize the five enzymes, in a way that the most stable could be reused after the inactivation of the least stable ones. After RML and LEU inactivation, the combi-biocatalysts were incubated in 0.5 M of ammonium sulfate to release the inactivated enzymes, incubated again with PEI and a new RML and LEU batch could be immobilized, maintaining the activity of the three most stable enzymes for at least five cycles of incubation at pH 7.0 and 60 °C for 3 h, incubation on ammonium sulfate, incubation in PEI and co-immobilization of new enzymes. The effect of the order of co-immobilization of the different enzymes on the co-immobilized biocatalyst activity was also investigated using different substrates, finding that when the most active enzyme versus one substrate was immobilized first (nearer to the surface of the particle), the activity was higher than when this enzyme was co-immobilized last (nearer to the particle core).

Directed evolution of Aspergillus oryzae lipase for the efficient resolution of (R,S)-ethyl-2-(4-hydroxyphenoxy) propanoate

Aspergillus oryzae lipase (AOL) is a potential biocatalyst for industrial application. In this study, a mutant lipase AOL-3^F38N/V230R was screened through two rounds of directed evolution, resulting in a fourfold increase in lipase activity, and threefold in catalytic efficiency (k_cat/K_m), while maintaining its excellent stereoselectivity. AOL-3^F38N/V230R enzyme activity was maximum at pH 7.5 and also at 40 °C. And compared with wild-type AOL-3, AOL-3^F38N/V230R preferentially hydrolyzed the fatty acid ethyl ester carbon chain length from C4 to C6-C10. In the same catalytic reaction conditions, the conversion of (R,S)-ethyl-2-(4-hydroxyphenoxy) propanoate ((R,S)-EHPP) by AOL-3^F38N/V230R can be increased 169.7% compared to the original enzyme. The e.e._s of (R,S)-EHPP achieved 99.4% and conversion about 50.2% with E value being 829.0. Therefore, AOL-3^F38N/V230R was a potential biocatalyst for obtaining key chiral compounds for aryloxyphenoxy propionate (APP) herbicides.

Lipase activation by molecular bioimprinting: The role of interactions between fatty acids and enzyme active site

Bioimprinting is an easy, sustainable and low-cost technique that promotes a printing of potential substrates on enzyme structure, inducing a more selective and stable conformation. Bioimprinting promotes conformational changes in enzymes, resulting in better catalytic performance. In this work, the effect of bioimprinting of Burkholderia cepacia lipase (BCL) and porcine pancreatic extracts (PPE) with four different fatty acids (lauric acid (C12:0), myristic acid (C14:0), palmitic acid (C16:0), and stearic acid (C18:0)) was investigated. The results demonstrated that the better bioimprinting effect was in BCL with lauric acid in esterification reaction, promoting BCL activation in which relative enzyme activity was 70 times greater than nonimprinted BCL. Bioimprinting results were influenced by the carbon chain length of fatty acids imprinted in the BCL, in which the effects were weaker with the chain increase. Molecular docking was performed to better understand the bioimprinting method. The results of these simulations showed that indeed all fatty acids were imprinted in the active site of BCL. However, lauric acid presented the highest imprinting preference in the active site of BCL, resulting in the highest relative activity. Furthermore, Fourier transform infrared (FTIR) analysis confirmed important variations in secondary structure of bioimprinting BCL with lauric acid, in which there was a reduction in the α-helix content and an increase in the β-sheet content that facilitated substrate access to the active site of BCL and led higher rigidity, resulting in high activity. Bioimprinted BCL with lauric acid showed excellent operational stability in esterification reaction, maintaining its original relative activity after five successive cycles. Thus, the results show that bioimprinting of BCL with lauric acid is a successful strategy due to its high catalytic activity and reusability.

Enzymatic transesterification of coconut oil by using immobilized lipase on biochar: An experimental and molecular docking study

Guava seed biochar appears as a new alternative of the effective support to the immobilization of Burkholderia cepacia lipase (BCL) by physical adsorption. The objective of this work was to evaluate the potential of this immobilized biocatalyst in the transesterification reaction of crude coconut oil and ethanol and to understand the mechanism of the reaction through the study of molecular docking. The best loading of BCL was determined to be 0.15 g_enzyme /g_support having a hydrolytic activity of 260 U/g and 54% immobilization yield. The products of transesterification reaction produced a maximum yield at 40 °C under different reaction conditions. The monoacylglycerols (MAGs) conversion of 59% was using substrate molar ratio oil:ethanol of 1:7 with the reaction time of 24 H. In addition, the highest ethyl esters yield (48%) had the molar ratio of 1:7 with the reaction time of 96 H and maximum conversion of diacylglycerols (DAGs) was 30% with the molar ratio of 1:6 with the reaction time of 24 H. Molecular Docking was applied to clarify the mechanisms of transesterification reaction at the molecular level. MAGs and DAGs are compounds with excellent emulsifying properties used in industrial production of several bioproducts such as cosmetic, pharmaceuticals, foods, and lubricants.

Calorimetric approach for comparison of Angiopoietin-like protein 4 with other pancreatic lipase inhibitors

Pancreatic lipase (PNLIP) is a digestive enzyme that is a potential drug target for the treatment of obesity. A better understanding of its regulation mechanisms would facilitate the development of new therapeutics. Recent studies indicate that intestinal lipolysis by PNLIP is reduced by Angiopoietin-like protein 4 (ANGPTL4), whose N-terminal domain (nANGPTL4) is a known inactivator of lipoprotein lipase (LPL) in blood circulation and adipocytes. To elucidate the mechanism of PNLIP inhibition by ANGPTL4, we developed a novel approach, using isothermal titration calorimetry (ITC). The obtained results were compared with those of well-described inhibitors of PNLIP - ε-polylysine (EPL), (-)-epigallocatechin-3-gallate (EGCG) and tetrahydrolipstatin. We demonstrate that ITC allows to investigate PNLIP inhibition mechanisms in complex substrate emulsions and that the ITC-based assay is highly sensitive - the lowest concentration for quantification of PNLIP is 1.5 pM. Combining ITC with surface plasmon resonance and fluorescence measurements, we present evidence that ANGPTL4 is a lipid-binding protein that influences PNLIP activity through interactions with components of substrate emulsions (bile salts, phospholipids and triglycerides), and this promotes the aggregation of triglyceride emulsions similarly to the PNLIP inhibitors EPL and EGCG. In the absence of substrate emulsion, unlike in the case of LPL, ANGPTL4 did not induce the inactivation of PNLIP. Our data also prove that due to various interactions with components of substrate systems, the effect of a PNLIP inhibitor depends on whether its effect is measured in a complex substrate emulsion or in a simple substrate system.

Methyl arachidonyl fluorophosphonate inhibits Mycobacterium tuberculosis thioesterase TesA and globally affects vancomycin susceptibility

Phthiocerol dimycocerosates and phenolic glycolipids (PGL) are considered as major virulence elements of Mycobacterium tuberculosis, in particular because of their involvement in cell wall impermeability and drug resistance. The biosynthesis of these waxy lipids involves multiple enzymes, including thioesterase A (TesA). We observed that purified recombinant M. tuberculosis TesA is able to dimerize in the presence of palmitoyl-CoA and our 3D structure model of TesA with this acyl-CoA suggests hydrophobic interaction requirement for dimerization. Furthermore, we identified that methyl arachidonyl fluorophosphonate, which inhibits TesA by covalently modifying the catalytic serine, also displays a synergistic antimicrobial activity with vancomycin further warranting the development of TesA inhibitors as valuable antituberculous drug candidates.

Analysis of the Lipolytic Activity of Whole-Saliva and Site-Specific Secretions from the Oral Cavity of Healthy Adults

It is currently unclear how the process of fat digestion occurs in the mouth of humans. This pilot study therefore aimed to quantify the levels of lipolytic activity at different sites of the mouth and in whole saliva. Samples of whole saliva and from 4 discrete sites in the oral cavity were collected from 42 healthy adult participants. All samples were analyzed for lipolytic activity using two different substrates (olive oil and the synthetic 1,2-o-dilauryl-rac-glycero-3-glutaric acid-(6’-methylresorufin) ester (DGGR)). Bland–Altman analyses suggested that the two assays gave divergent results, with 91% and 23% of site-specific and 40% and 26% of whole-saliva samples testing positive for lipolytic activity, respectively. Non-parametric multiple comparisons tests highlighted that median (IQR) of lipolytic activity (tested using the olive oil assay) of the samples from the parotid 20.7 (11.7–31.0) and sublingual 18.4 (10.6–47.2) sites were significantly higher than that of whole saliva 0.0 (0.0–35.7). In conclusion, lipolysis appears to occur in the oral cavity of a proportion of individuals. These findings give a preliminary indication that lipolytic agent activity in the oral cavity may be substrate-specific but do not discount that the enzyme is from sources other than oral secretions (e.g., microbes, gastric reflux).

Influence of gene regulation on rice quality: Impact of storage temperature and humidity on flavor profile

Effects of high temperature-high humidity (HT-HH) storage on the flavor profile of rice were investigated. Volatile compounds such as aldehydes, ketones, and furans increased when rice was stored under HT-HH conditions, leading to a pronounced deterioration in rice quality. Correspondingly, the fatty acid content of the rice significantly increased during storage. Lipid oxidation was also accelerated under HT-HH conditions leading to the formation of peroxides. However, catalase activity was reduced under these conditions promoting the accumulation of peroxides. For the first time, insights into the genetic mechanisms responsible for these changes were obtained using RNA-sequencing to establish the flavor metabolic pathways in rice. Under HT-HH conditions, gene expression of lipase increased while that of catalase decreased, leading to faster hydrolysis and oxidation of the rice lipids. As a result, a series of lipid degradation products was formed (such as fatty acids, aldehydes, and ketones) that decreased the rice flavor quality.

Discovery of arginine-containing tripeptides as a new class of pancreatic lipase inhibitors

Aim: The inhibition of pancreatic lipase (PL) represents one of the most promising strategies in the search for novel antiobesity drugs. We propose here a pioneering course by exploring tripeptide scaffolds in the way to selective PL inhibitors. Methodology/Results: The peptide series exhibited good PL inhibitory properties in vitro, with all the strongest inhibitors sharing a central arginine, shown in silico to be relevant for the active site-directed activity. The compounds were found devoid of inhibitory properties on acetylcholinesterase. Conclusion: Present results disclosed that basic tripeptides are able to interact efficiently with the PL-binding pocket, where they adopt a binding pose suitable for functional-to-inhibition interactions with key amino acids. Main inhibitor MALA4 may be selected as lead for further optimization.

Tailoring Emulsions for Controlled Lipid Release: Establishing in vitro-in Vivo Correlation for Digestion of Lipids

The use of oil-in-water emulsions for controlled lipid release is of interest to the pharmaceutical industry in the development of poorly water soluble drugs and also has gained major interest in the treatment of obesity. In this study, we focus on the relevant in vitro parameters reflecting gastric and intestinal digestion steps to reach a reliable in vitro-in vivo correlation for lipid delivery systems. We found that (i) gastric lipolysis determines early lipid release and sensing. This was mainly influenced by the emulsion stabilization mechanism. (ii) Gastric mucin influences the structure of charge-stabilized emulsion systems in the stomach, leading to destabilization or gel formation, which is supported by in vivo magnetic resonance imaging in healthy volunteers. (iii) The precursor structures of these emulsions modulate intestinal lipolysis kinetics in vitro, which is reflected in plasma triglyceride and cholecystokinin concentrations in vivo.

The production, properties, and applications of thermostable steryl glucosidases

Extremophilic microorganisms are a rich source of enzymes, the enzymes which can serve as industrial catalysts that can withstand harsh processing conditions. An example is thermostable β-glucosidases that are addressing a challenging problem in the biodiesel industry: removing steryl glucosides (SGs) from biodiesel. Steryl glucosidases (SGases) must be tolerant to heat and solvents in order to function efficiently in biodiesel. The amphipathic nature of SGs also requires enzymes with an affinity for water/solvent interfaces in order to achieve efficient hydrolysis. Additionally, the development of an enzymatic process involving a commodity such as soybean biodiesel must be cost-effective, necessitating an efficient manufacturing process for SGases. This review summarizes the identification of microbial SGases and their applications, discusses biodiesel refining processes and the development of analytical methods for identifying and quantifying SGs in foods and biodiesel, and considers technologies for strain engineering and process optimization for the heterologous production of a SGase from Thermococcus litoralis. All of these technologies might be used for the production of other thermostable enzymes. Structural features of SGases and the feasibility of protein engineering for novel applications are explored.

New lipases by mining of Pleurotus ostreatus genome

The analysis of Pleurotus ostreatus genome reveals the presence of automatically annotated 53 lipase and 34 carboxylesterase putative coding-genes. Since no biochemical or physiological data are available so far, a functional approach was applied to identify lipases from P. ostreatus. In the tested growth conditions, four lipases were found expressed, with different patterns depending on the used C source. Two of the four identified proteins (PleoLip241 and PleoLip369), expressed in both analysed conditions, were chosen for further studies, such as an in silico analysis and their molecular characterization. To overcome limits linked to native production, a recombinant expression approach in the yeast Pichia pastoris was applied. Different expression levels were obtained: PleoLip241 reached a maximum activity of 4000 U/L, whereas PleoLip369 reached a maximum activity of 700 U/L. Despite their sequence similarity, these enzymes exhibited different substrate specificity and diverse stability at pH, temperature, and presence of metals, detergents and organic solvents. The obtained data allowed classifying PleoLip241 as belonging to the “true lipase” family. Indeed, by phylogenetic analysis the two proteins fall in different clusters. PleoLip241 was used to remove the hydrophobic layer from wool surface in order to improve its dyeability. The encouraging results obtained with lipase treated wool led to forecast PleoLip241 applicability in this field.

Recombinant Lipase from Gibberella zeae Exhibits Broad Substrate Specificity: A Comparative Study on Emulsified and Monomolecular Substrate

Using the classical emulsified system and the monomolecular film technique, the substrate specificity of recombinant Gibberella zeae lipase (rGZEL) that originates from Gibberella zeae was characterized in detail. Under the emulsified reaction system, both phospholipase and glycolipid hydrolytic activities were observed, except for the predominant lipase activity. The optimum conditions for different activity exhibition were also determined. Compared with its lipase activity, a little higher ratio of glycolipid hydrolytic activity (0.06) than phospholipase activity (0.02) was found. rGZEL preferred medium chain-length triglycerides, while lower activity was found for the longer-chain triglyceride. Using the monomolecular film technique, we found that the preference order of rGZEL to different phospholipids was 1,2-diacyl-sn-glycero-3-phospho-l-serine (PS) > 1,2-dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt (PG) > 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) > l-α-phosphatidylinositol (PI) > cardiolipin (CL) > 3-sn-phosphatidic acid sodium salt (PA) > l-α-phosphatidylethanolamine (PE), while no hydrolytic activity was detected for sphingomyelin (SM). Moreover, rGZEL showed higher galactolipase activity on 1,2-distearoyimonoglactosylglyceride (MGDG). A kinetic study on the stereo- and regioselectivity of rGZEL was also performed by using three pairs of pseudodiglyceride enantiomers (DDGs). rGZEL presented higher preference for distal DDG enantiomers than adjacent ester groups, however, no hydrolytic activity to the sn-2 position of diglyceride analogs was found. Furthermore, rGZEL preferred the R configuration of DDG enantiomers. Molecular docking results were in concordance with in vitro tests.

Constitutive expression of human gastric lipase in Pichia pastoris and site-directed mutagenesis of key lid-stabilizing residues

The cDNA encoding human gastric lipase (HGL) was integrated into the genome of Pichia pastoris using the pGAPZα A transfer vector. The HGL signal peptide was replaced by the yeast α-factor to achieve an efficient secretion. Active rHGL was produced by the transformed yeast but its levels and stability were dependent on the pH. The highest activity was obtained upon buffering the culture medium at pH5, a condition that allowed preserving enzyme activity over time. A large fraction (72±2%) of secreted rHGL remained however bound to the yeast cells, and was released by washing the cell pellet with an acid glycine-HCl buffer (pH2.2). This procedure allowed establishing a first step of purification that was completed by size exclusion chromatography. N-terminal sequencing and MALDI-ToF mass spectrometry revealed that rHGL was produced in its mature form, with a global mass of 50,837±32Da corresponding to a N-glycosylated form of HGL polypeptide (43,193Da). rHGL activity was characterized as a function of pH, various substrates and in the presence of bile salts and pepsin, and was found similar to native HGL, except for slight changes in pH optima. We then studied by site-directed mutagenesis the role of three key residues (K4, E225, R229) involved in salt bridges stabilizing the lid domain that controls the access to the active site and is part of the interfacial recognition site. Their substitution has an impact on the pH-dependent activity of rHGL and its relative activities on medium and long chain triglycerides.