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Showing papers on "Lipase published in 2014"


Journal ArticleDOI
TL;DR: The main emphasis is to study the nature of organic solvent tolerant lipases, and the potential industrial applications that make lipases the biocatalysts of choice for the present and future have been presented.
Abstract: Lipases are a group of enzymes naturally endowed with the property of performing reactions in aqueous as well as organic solvents. The esterification reactions using lipase(s) could be performed in water-restricted organic media as organic solvent(s) not only improve(s) the solubility of substrate and reactant in reaction mixture but also permit(s) the reaction in the reverse direction, and often it is easy to recover the product in organic phase in two-phase equilibrium systems. The use of organic solvent tolerant lipase in organic media has exhibited many advantages: increased activity and stability, regiospecificity and stereoselectivity, higher solubility of substrate, ease of products recovery, and ability to shift the reaction equilibrium toward synthetic direction. Therefore the search for organic solvent tolerant enzymes has been an extensive area of research. A variety of fatty acid esters are now being produced commercially using immobilized lipase in nonaqueous solvents. This review describes the organic tolerance and industrial application of lipases. The main emphasis is to study the nature of organic solvent tolerant lipases. Also, the potential industrial applications that make lipases the biocatalysts of choice for the present and future have been presented.

225 citations


Journal ArticleDOI
TL;DR: In this paper, a magnetic composite poly(styrene-methacrylic acid) microsphere, was prepared using oleic acid-coated magnetic nanoparticles as seeds by microemulsion copolymerization of styrene (St) and methacric acid (MAA), and the lipase from Candida rugosa was then covalently bound to the magnetic polymercoated microspheres by using 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDAC) as an activation re
Abstract: A magnetic composite poly(styrene-methacrylic acid) microsphere, was prepared using oleic acid-coated magnetic nanoparticles as seeds by microemulsion copolymerization of styrene (St) and methacrylic acid (MAA). The lipase from Candida rugosa was then covalently bound to the magnetic polymer-coated microspheres by using 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDAC) as an activation reagent. The immobilization of lipase could enhance the thermal and pH stability of lipase activity when compared to free lipase. The immobilized lipase microspheres were characterized by lipase activity assays, Fourier transform infrared spectroscopy, powder X-ray diffraction, transmission electron microscopy, and vibrating-sample magnetometer techniques. The bound lipase showed high activities to soybean oil transesterification with methanol to produce biodiesel. It was found that the oil conversion of 86% was attained at a reaction temperature of 35 °C for 24 h. The immobilized lipase is stable with re...

175 citations


Journal ArticleDOI
Ze-Lin Huang1, Ben-Pei Wu1, Qing Wen1, Tao-Xiang Yang1, Zhen Yang1 
TL;DR: In this article, deep eutectic solvents (DESs) have recently attracted widespread interests as new green solutions for (bio)chemical transformations, and they have been widely used as green solutions.
Abstract: BACKGROUND Deep eutectic solvents (DESs) have recently attracted widespread interests as new green solvents for (bio)chemical transformations. In this study, 24 DESs were prepared to study their effects on enzymatic performance: two cholinium salts (ChCl and ChAc) combined with four H-bond donors (HBDs) (urea, glycerol, acetamide, ethylene glycol) at three molar ratios. RESULTS In DES-containing aqueous solution, Penicillium expansum lipase (PEL) can be activated and stabilized up to 2.4 times and 18.4 times its original values, respectively. When DESs were used alone as the reaction medium to produce biodiesel from Millettia pinnata seed oil, Novozym 435 enabled a better conversion than PEL, with a maximal yield obtained in ChAc/glycerol (1:2). These DES effects arise from the formation of DES rather than from the synergetic action contributed by each of its components. Preliminary toxicity tests on Hydra sinensis suggest that a DES may be less toxic than its components. CONCLUSION DESs are viable solvents/cosolvents for lipase-catalyzed reactions, and both lipase activity and stability are affected by the choice of DES components (salts and HBDs) and their molar ratios. In both reaction systems above, the ChAc-based DESs were superior to the ChCl-based ones, while glycerol showed better compatibility with lipase than the other three HBDs tested. © 2013 Society of Chemical Industry

161 citations


Journal ArticleDOI
TL;DR: The impact of polysaccharides on lipid digestion was attributed to their ability to induce droplet flocculation, and/or due to their interactions with molecular species involved in lipid hydrolysis, such as bile salts, fatty acids, and calcium.
Abstract: A simulated in vitro digestion model was used to elucidate the impact of dietary fibers on the digestion rate of emulsified lipids. The influence of polysaccharide type (chitosan (cationic), methyl cellulose (non-ionic), and pectin (anionic)) and initial concentration (0.4 to 3.6% (w/w)) was examined. 2% (w/w) corn oil-in-water emulsions stabilized by 0.2% (w/w) Tween-80 were prepared, mixed with polysaccharide, and then subjected to an in vitro digestion model (37 °C): initial (pH 7.0); oral (pH 6.8; 10 min); gastric (pH 2.5; 120 min); and, intestinal (pH 7.0; 120 min) phases. The impact of polysaccharides on lipid digestion, ζ-potential, particle size, viscosity, and stability was determined. The rate and extent of lipid digestion decreased with increasing pectin, methyl cellulose, and chitosan concentrations. The free fatty acids released after 120 min of lipase digestion were 46, 63, and 81% (w/w) for methyl cellulose, pectin, and chitosan, respectively (3.6% (w/w) initial polysaccharide), indicating that methyl cellulose had the highest capacity to inhibit lipid digestion, followed by pectin, and then chitosan. The impact of the polysaccharides on lipid digestion was attributed to their ability to induce droplet flocculation, and/or due to their interactions with molecular species involved in lipid hydrolysis, such as bile salts, fatty acids, and calcium. These results have important implications for understanding the influence of dietary fibers on lipid digestion. The control of lipid digestibility within the gastrointestinal tract might be important for the development of reduced-calorie emulsion-based functional food products.

159 citations


Journal ArticleDOI
TL;DR: This is the first study in which the microstructural properties of a macromolecule are examined in a deep eutectic solvent and it was found that urea molecules denature the enzyme by interrupting the intra-chain hydrogen bonds in a "direct denaturation mechanism".
Abstract: Deep eutectic solvents (DESs) are utilized as green and inexpensive alternatives to classical ionic liquids. It has been known that some of DESs can be used as solvent in the enzymatic reactions to obtain very green chemical processes. DESs are quite poorly understood at the molecular level. Moreover, we do not know much about the enzyme microstructure in such systems. For example, how some hydrolase can remain active and stable in a deep eutectic solvent including 9 M of urea? In this study, the molecular dynamics of DESs as a liquid was simulated at the molecular level. Urea : choline chloride as a well-known eutectic mixture was chosen as a model DES. The behavior of the lipase as a biocatalyst was studied in this system. For comparison, the enzyme structure was also simulated in 8M urea. The thermal stability of the enzyme was also evaluated in DESs, water, and 8M urea. The enzyme showed very good conformational stability in the urea : choline chloride mixture with about 66% urea (9 M) even at high temperatures. The results are in good agreement with recent experimental observations. In contrast, complete enzyme denaturation occurred in 8M urea with only 12% urea in water. It was found that urea molecules denature the enzyme by interrupting the intra-chain hydrogen bonds in a “direct denaturation mechanism”. However, in a urea : choline chloride deep eutectic solvent, as a result of hydrogen bonding with choline and chloride ions, urea molecules have a low diffusion coefficient and cannot reach the protein domains. Interestingly, urea, choline, and chloride ions form hydrogen bonds with the surface residues of the enzyme which, instead of lipase denaturation, leads to greater enzyme stability. To the best of our knowledge, this is the first study in which the microstructural properties of a macromolecule are examined in a deep eutectic solvent.

150 citations


Journal ArticleDOI
TL;DR: Data show that PNPLA3 has a predominant lipase activity and I148M mutation results in a loss of function, which is similar to that of the wild type protein.

149 citations


Journal ArticleDOI
TL;DR: This review aims at compiling the information on various yeast lipase catalyzed transesterification reactions for greener production of biodiesel.
Abstract: Biodiesel has provided an eco-friendly solution to fuel crisis, as it is renewable, biodegradable and a non-toxic fuel that can be easily produced through enzymatic transesterification of vegetable oils and animal fats. Enzymatic production of biodiesel has many advantages over the conventional methods as high yields can be obtained at low reaction temperatures with easy recovery of glycerol. Microbial lipases are powerful biocatalysts for industrial applications including biodiesel production at lower costs due to its potential in hydrolyzing waste industrial materials. Among them, lipases from yeasts, Candida antarctica, Candida rugosa, Cryptococcus sp., Trichosporon asahii and Yarrowia lipolytica are known to catalyze such reactions. Moreover, stepwise addition of methanol in a three step, two step and single step reactions have been developed using yeast lipases to minimize the inhibitory effects of methanol. The latest trend in biodiesel production is the use of whole-cell as biocatalysts, since the process requires no downstream processing of the enzyme. Synthesis of value added products from the byproduct glycerol further reduces the production cost of biodiesel. This review aims at compiling the information on various yeast lipase catalyzed transesterification reactions for greener production of biodiesel.

138 citations


Journal ArticleDOI
01 Nov 2014-Fuel
TL;DR: To the best of the authors' knowledge, this is the first time that an enzyme/enzyme hydroesterification process using low cost biocatalysts obtained from vegetable and microorganism using solvent-free media in both reactions is described for the conversion of an acid and low value oil into biodiesel.

130 citations


Journal ArticleDOI
TL;DR: Using carboxyl functionalized silica-coated magnetic nanoparticles (MNPs) as carrier, a novel immobilized porcine pancreatic lipase (PPL) was prepared through the 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) coupling reaction.

128 citations


Journal ArticleDOI
TL;DR: It is suggested that the Q185L substitution facilitates a closed lid conformation that limits access for both the methanol and substrate excess into the active site, which makes this variant a potential biocatalyst for biodiesel production.
Abstract: The abilities of enzymes to catalyze reactions in nonnatural environments of organic solvents have opened new opportunities for enzyme-based industrial processes. However, the main drawback of such processes is that most enzymes have a limited stability in polar organic solvents. In this study, we employed protein engineering methods to generate a lipase for enhanced stability in methanol, which is important for biodiesel production. Two protein engineering approaches, random mutagenesis (error-prone PCR) and structure-guided consensus, were applied in parallel on an unexplored lipase gene from Geobacillus stearothermophilus T6. A high-throughput colorimetric screening assay was used to evaluate lipase activity after an incubation period in high methanol concentrations. Both protein engineering approaches were successful in producing variants with elevated half-life values in 70% methanol. The best variant of the random mutagenesis library, Q185L, exhibited 23-fold-improved stability, yet its methanolysis activity was decreased by one-half compared to the wild type. The best variant from the consensus library, H86Y/A269T, exhibited 66-fold-improved stability in methanol along with elevated thermostability (+4.3°C) and a 2-fold-higher fatty acid methyl ester yield from soybean oil. Based on in silico modeling, we suggest that the Q185L substitution facilitates a closed lid conformation that limits access for both the methanol and substrate excess into the active site. The enhanced stability of H86Y/A269T was a result of formation of new hydrogen bonds. These improved characteristics make this variant a potential biocatalyst for biodiesel production.

100 citations


Journal ArticleDOI
TL;DR: The immobilization of a new lipase isolated from oleaginous seeds of Pachira aquatica, using beads of calcium alginate and poly(vinyl alcohol) and PVA, found to be optimally active between 30 and 40°C and more stable than the free enzyme.
Abstract: This study reports the immobilization of a new lipase isolated from oleaginous seeds of Pachira aquatica, using beads of calcium alginate (Alg) and poly(vinyl alcohol) (PVA). We evaluated the morphology, number of cycles of reuse, optimum temperature, and temperature stability of both immobilization methods compared to the free enzyme. The immobilized enzymes were more stable than the free enzyme, keeping 60% of the original activity after 4 h at 50°C. The immobilized lipase was reused several times, with activity decreasing to approximately 50% after 5 cycles. Both the free and immobilized enzymes were found to be optimally active between 30 and 40°C.

Journal ArticleDOI
TL;DR: This review provides a general overview of the recent advances in lipase engineering, including both protein modification and production, and the current challenges and perspectives for potential solutions.
Abstract: Biodiesel is an environment-friendly and renewable fuel produced by transesterification of various feedstocks. Although the lipase-catalyzed biodiesel production has many advantages over the conventional alkali catalyzed process, its industrial applications have been limited by high-cost and low-stability of lipase enzymes. This review provides a general overview of the recent advances in lipase engineering, including both protein modification and production. Recent advances in biotechnology such as in protein engineering, recombinant methods and metabolic engineering have been employed but are yet to impact lipase engineering for cost-effective production of biodiesel. A summary of the current challenges and perspectives for potential solutions are also provided.

Journal ArticleDOI
TL;DR: Cross-linked enzyme aggregates of lipase Candida sp.
Abstract: With the aim to provide a highly stable and active biocatalyst, cross-linked enzyme aggregates (CLEAs) of lipase Candida sp. 99-125 were prepared in three-dimensionally ordered macroporous silica materials (CLEAs-LP@3DOM-SiO2). Lipase Candida sp. 99-125 was first precipitated in the pores of 3DOM SiO2 (named EAs-LP@3DOM-SiO2), and further cross-linked by glutaraldehyde to form CLEAs-LP@3DOM-SiO2. Saturated ammonium sulfate was used as a precipitant and glutaraldehyde with a concentration of 0.25% (w/w) was employed as a cross-linker. Compared with EAs-LP@3DOM-SiO2 and native lipase, CLEAs-LP@3DOM-SiO2 exhibited excellent thermal and mechanical stability, and could maintain more than 85% of initial activity after 16 days of shaking in organic and aqueous phase. When CLEAs-LP@3DOM-SiO2 was applied in esterification and transesterification reactions, improved activity and reusability were achieved. This method can be used for the immobilization of other enzymes of interest.

Journal ArticleDOI
TL;DR: Alginates have the potential to be a well-tolerated obesity treatment and are effective inhibitors of pancreatic lipase, according to the structure of the polymer.

Journal ArticleDOI
TL;DR: A novel and robust recombinant Pichia pastoris yeast whole cell catalyst with functional intracellular expression of Thermomyces lanuginosus lipase with better catalytic performance than Lipozyme TLIM with respect to biodiesel yield and productivity is suggested, thus suggesting a promising cost-effective biocatalyst for biodiesel production.

Journal ArticleDOI
TL;DR: Results demonstrated that Pickering emulsion system stabilized by immobilized enzyme may possess much potential in many enzymatic industrial applications.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the effect of chokeberry extract on the activity of porcine pancreatic α-amylase and lipase and found that methanolic and acetic chokeberry extracts exhibited the highest inhibitory activities against α-AMylase with the IC 50 values of 10.31−±−0.04% and pancreatic lipase 83.45−±0.50% respectively.


Journal ArticleDOI
TL;DR: In this paper, core-shell supports have been prepared and utilized to immobilize lipase B from Candida antarctica, and different supports were prepared having different hydrophobicity and crosslinking degree compared to the commercially available.
Abstract: Core–shell supports have been prepared and utilized to immobilize lipase B from Candida antarctica . The hydrophobic nature of the supports permitted to immobilize the enzyme via interfacial activation at low ionic strength. Different supports were prepared having different hydrophobicity and crosslinking degree, and compared to the commercially available. Accurel MP 1000 (hydrophobic macroporous polymer of propylene) is a commercial support described as advantageous in different circumstances and it was used as comparative control in the process of immobilization. The immobilized lipase preparations were evaluated in the hydrolysis of p -nitro-phenyl laurate and the esterification of oleic acid with ethanol. On the kinetic resolution of (±)-1,2- O -isopropylidene-3,6-di- O -benzyl- myo -inositol, vinyl acetate was used as activated acyl donor. Results were very diverse, as the lipase properties may be easily tuned via immobilization, and some of the supports permitted to obtain activities even a two fold factor higher than the same amount of lipase immobilized in Accurel MP 1000. Moreover, in many instances, the loading of the support with enzyme produced reduced total activity in some reactions while not in other. This was explained by changes in the physical properties of the support surface that may alter the entry of substrates. Supports PS- co -DVB/PS- co -DVB 25% and PMMA- co -DVB/PMMA- co -DVB 25% presented very good features to immobilize CALB.

Journal ArticleDOI
TL;DR: The results revealed that 0.18 g/L nitrate concentration was the optimal for cultivation of microalgae, however, the highest lipid content was achieved in the absence of nitrate (0.0g/L), which was 7 folds higher compared to the alkaline based transesterification.

Journal ArticleDOI
TL;DR: This review discusses the efforts that have been made to use YL lipase as an industrial biocatalyst, including enzyme production and recovery, and the methods of immobilization are discussed.
Abstract: Yarrowia lipolytica (YL) is a “non-conventional” yeast that is capable of producing important metabolites. One of the most important products secreted by this microorganism is lipase, a ubiquitous enzyme that has considerable industrial potential and can be used as a biocatalyst in the pharmaceutical, food and environmental industries. This review discusses the efforts that have been made to use YL lipase as an industrial biocatalyst, including enzyme production and recovery. Special attention is given to a compilation of relevant information on enzyme separation and purification, since it is a key step for LYL application, that is not detailed in other reviews in the field. Because immobilized enzymes are preferentially used as commercial lipases, the methods of immobilization are also discussed and important biotechnological applications are addressed.

Journal ArticleDOI
TL;DR: This review provides a brief overview of lipases and esterases and examines specific structural motifs and evolutionary adaptations of halophilic lipases, and provides an in-depth look at an exciting algal-based biofuel production system.
Abstract: Lipases and esterases are enzymes which hydrolyze ester bonds between a fatty acid moiety and an esterified conjugate, such as a glycerol or phosphate. These enzymes have a wide spectrum of use in industrial applications where their high activity, broad substrate specificity, and stability under harsh conditions have made them integral in biofuel production, textile processing, waste treatment, and as detergent additives. To date, these industrial applications have mainly leveraged enzymes from mesophilic and thermophilic organisms. However, increasingly, attention has turned to halophilic enzymes as catalysts in environments where high salt stability is desired. This review provides a brief overview of lipases and esterases and examines specific structural motifs and evolutionary adaptations of halophilic lipases. Finally, we examine the state of research involving these enzymes and provide an in-depth look at an exciting algal-based biofuel production system. This system uses a recombinant halophilic lipase to increase oil production efficiency by cleaving algal fatty acids from the acyl carrier protein, which eliminates feedback inhibition of fatty acid synthesis.

Journal ArticleDOI
TL;DR: The synthesis, properties and enzyme activity of self-contained reactive biofluids based on solvent-free melts of lipase-polymer surfactant nanoconjugates are described and the efficiency of product formation increases as the temperature is raised to 150 °C.
Abstract: Enzymatic reactions typically occur in aqueous media or with hydrated enzymes. Here, the authors form fluid enzyme-polymer conjugates with sub-solvation levels of water, and demonstrate catalytic hydrolysis in the absence of a solvent at high temperatures.

Journal ArticleDOI
TL;DR: In this article, the incorporation of ultrasound and its improved impact in the lipase-catalysed esterification was discussed. And the optimisation of various parameters affecting the synthesis of ester in presence of ultrasound was done.

Journal ArticleDOI
TL;DR: Reusability of the combi-lipase showed that it could be used for at least 15 cycles without any significant decrease, and might be a useful technology for reactions including full modification of heterogeneous substrates.
Abstract: The concept of the combi-lipase biocatalyst has been proposed. It is based on the combination of different lipases as biocatalysts in reactions using heterogeneous substrates. The hydrolysis of soybean oil was evaluated as a model substrate, and Novozym 435 (CALB), Lipozyme TL-IM (TLL), and Lipozyme RM-IM (RML) were used as biocatalysts. Results showed that, although individually TLL was the most active enzyme, whereas CALB was the less active one, the combination of 80% of RML and 20% of CALB was the best biocatalyst. Reaction parameters were optimized, allowing to obtain more than 80% hydrolysis in 24 h using the combi-lipase, up from less than 50% with any individual lipase. Reusability of the combi-lipase showed that it could be used for at least 15 cycles without any significant decrease. The concept of the combi-biocatalyst might be a useful technology for reactions including full modification of heterogeneous substrates.

Journal ArticleDOI
TL;DR: Evidence is presented that recombinant Angptl4 reduced the activity of pancreatic lipase as well as the lipase activity in human ileostomy output and suggests that Angiopoietin-like 4 is an endogenous inhibitor of intestinallipase activity.
Abstract: Dietary triglycerides are hydrolyzed in the small intestine principally by pancreatic lipase Following uptake by enterocytes and secretion as chylomicrons, dietary lipids are cleared from the bloodstream via lipoprotein lipase Whereas lipoprotein lipase is inhibited by several proteins including Angiopoietin-like 4 (Angptl4), no endogenous regulator of pancreatic lipase has yet been identified Here we present evidence that Angptl4 is an endogenous inhibitor of dietary lipid digestion Angptl4−/− mice were heavier compared to their wild-type counterparts without any difference in food intake, energy expenditure or locomotor activity However, Angptl4−/− mice showed decreased lipid content in the stools and increased accumulation of dietary triglycerides in the small intestine, which coincided with elevated luminal lipase activity in Angptl4−/− mice Furthermore, recombinant Angptl4 reduced the activity of pancreatic lipase as well as the lipase activity in human ileostomy output In conclusion, our data suggest that Angptl4 is an endogenous inhibitor of intestinal lipase activity

Journal ArticleDOI
Xuli Wu1, Weiyi He1, Haiping Zhang2, Yao Li1, Zhigang Liu1, Zhendan He1 
TL;DR: Characterization of acteoside and lipase by fluorescence spectroscopy, isothermal titration calorimetry and circular dichroism revealed that acteooside might act as a non-competitive lipase inhibitor.

Journal ArticleDOI
TL;DR: The result demonstrated the beneficial biochemical effects of Moringa stenopetala by inhibiting intestinal α-glucosidase, pancreatic cholesterol esterase and pancreatic lipase activities and finding out the relevance of the plant in controlling blood sugar and lipid levels.
Abstract: Moringa stenopetala has been used in traditional health systems to treat diabetes mellitus. One of the successful methods to prevent of the onset of diabetes is to control postprandial hyperglycemia by the inhibition of α-glucosidase and pancreatic α-amylase activities, resulting in the aggressive delay of the carbohydrate digestion of absorbable monosaccharides. The aim of the present study is to investigate the effect of the extract of the leaves of Moringa stenopetala on α-glucosidase, pancreatic α-amylase, pancreatic lipase, and pancreatic cholesterol esterase activities, and, therefore find out the relevance of the plant in controlling blood sugar and lipid levels. The dried leaves of Moringa stenopetala were extracted with hydroalcoholic solvent and dried using rotary vapor under reduced pressure. The dried extracts were determined for the total phenolic compounds, flavonoid content and condensed tannins content by using Folin-Ciocateu’s reagent, AlCl3 and vanillin assay, respectively. The dried extract of plant-based food was further quantified with respect to intestinal α-glucosidase (maltase and sucrase) inhibition and pancreatic α-amylase inhibition by glucose oxidase method and dinitrosalicylic (DNS) reagent, respectively. The phytochemical analysis indicated that flavonoid, total phenolic, and condensed tannin contents in the extract were 71.73 ± 2.48 mg quercetin equivalent/g of crude extract, 79.81 ± 2.85 mg of gallic acid equivalent/g of crude extract, 8.82 ± 0.77 mg catechin equivalent/g of crude extract, respectively. The extract inhibited intestinal sucrase more than intestinal maltase with IC50 value of 1.47 ± 0.19 mg/ml. It also slightly inhibited pancreatic α-amylase, pancreatic lipase and pancreatic cholesterol esterase. The result demonstrated the beneficial biochemical effects of Moringa stenopetala by inhibiting intestinal α-glucosidase, pancreatic cholesterol esterase and pancreatic lipase activities. A daily supplement intake of the leaves of Moringa stenopetala may help in reducing hyperglycemia and hyperlipidemia.

Journal ArticleDOI
TL;DR: In this paper, the SAL2 lipase was shown to be one of the most abundant proteins secreted by USA300 and is proteolytically processed from the 72-kDa proSAL2 to the 44-k Da mature SAL2 by the metalloprotease aureolysin.
Abstract: Part of the human host innate immune response involves the secretion of bactericidal lipids on the skin and delivery of triglycerides into abscesses to control invading pathogens. Two Staphylococcus aureus lipases, named SAL1 and SAL2, were identified in the community-associated methicillin-resistant S. aureus strain USA300, which, presumably, are produced and function to degrade triglycerides to release free fatty acids. We show that the SAL2 lipase is one of the most abundant proteins secreted by USA300 and is proteolytically processed from the 72-kDa proSAL2 to the 44-kDa mature SAL2 by the metalloprotease aureolysin. We show that spent culture supernatants had lipase activity on both short- and long-chain fatty acid substrates and that deletion of gehB, encoding SAL2, resulted in the complete loss of these activities. With the use of gas chromatography-mass spectrometry, we show that SAL2 hydrolyzed trilinolein to linoleic acid, a fatty acid with known antistaphylococcal properties. When added to cultures of USA300, trilinolein and, to a lesser extent, triolein inhibited growth in a SAL2-dependent manner. This effect was shown to be due to the enzymatic activity of SAL2 on these triglycerides, since the catalytically inactive SAL2 Ser412Ala mutant was incapable of hydrolyzing the triglycerides or yielding delayed growth in their presence. Overall, these results reveal that SAL2 hydrolyzes triglycerides of both short- and long-chain fatty acids and that the released free fatty acids have the potential to cause significant delays in growth, depending on the chemical nature of the free fatty acid.

Journal ArticleDOI
TL;DR: Electrophoresis, microstructure, and turbidity measurements showed that anionic pectin formed electrostatic complexes with calcium ions, which may have decreased lipid digestion due to increased lipid flocculation or microgel formation because this would reduce the surface area of lipid exposed to the lipase.
Abstract: An in vitro gastrointestinal model consisting of oral, gastric, and intestinal phases was used to elucidate the impact of pectin on the digestion of emulsified lipids. Pectin reduced the extent of lipid digestion, which was attributed to its binding interactions with specific gastrointestinal components. The interaction of pectin with bile salts, lipase, CaCl2, and NaCl was therefore investigated by turbidity, microstructure, electrophoresis, and isothermal titration calorimetry (ITC) at pH 7.0 and 37 °C. ITC showed that the interaction of pectin was endothermic with bile salts, but exothermic with CaCl2, NaCl, and lipase. Electrophoresis, microstructure, and turbidity measurements showed that anionic pectin formed electrostatic complexes with calcium ions, which may have decreased lipid digestion due to increased lipid flocculation or microgel formation because this would reduce the surface area of lipid exposed to the lipase. This research provides valuable insights into the physicochemical and molecular mechanisms of the interaction of pectin with gastrointestinal components that may affect the rate and extent of lipid digestion.