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Lipase
Kinds of Lipase Terms modified by Lipase Selected AbstractsEFFECT OF HIGH-PRESSURE TREATMENT OF MILK ON LIPASE AND ,-GLUTAMYL TRANSFERASE ACTIVITYJOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2004P. K. PANDEY ABSTRACT High-pressure (HP) treatment (0,180 min at 300,400 MPa) was applied to milk to evaluate the pressure effects on the activities of lipoprotein lipase and ,-glutamyl transferase. Short time pressure exposure resulted in some enhancement in the activity of both enzymes, and for lipase, there was no inactivation during the entire pressure hold time (up to 100 min). With ,-glutamyl transferase, the extent of enhancement in activity was pressure level dependent, with lower pressure resulting in a greater enhancement. Furthermore, longer pressure treatment times resulted in inactivation of ,-glutamyl transferase, following a first order kinetic model. The pressure sensitivity of the inactivation parameters (k and D -values) for ,-glutamyl transferase was adequately described by the pressure death time and Arrhenius models with a zpof 543 MPa and an associated volume of activation, ,V,, of ,3.28 × 10,8 m3/mole. [source] THE DEGRADATION OF CHlTOSAN WITH THE AID OF LIPASE FROM RHIZOPUS JAPONICUS FOR THE PRODUCTION OF SOLUBLE CHlTOSANJOURNAL OF FOOD BIOCHEMISTRY, Issue 4 2001SEUNG S. SHIN ABSTRACT Lipase from Rhizopus japonicus degraded chitosan resulting in soluble chitosan hydrolysates with molecular weight of about 30,50 kDa as shown by size exclusion chromatography. Optimal temperature for the hydrolysis of chitosan was 40C. The chitosan degradation products were fractionated stepwise according to their molecular weights by ultrafiltration with the filtration range of over 0.1 ,m, 0. l ,m to 30 kDa, 30 kDa to 10 kDa, 10 to 3 kDa, and 3 to 0.2 kDa. These fractions exhibited molecular weights of 50, 41, 41, 35, and 30 kDa, respectively. The molecular weights did not coincide with the pore size of filter membranes. Chitosan hydrolysate exhibited almost the same structural composition in IR spectra as chitosan flakes, except the peak of 1550 nm,1 that appeared to be the COO residue shifted from sodium acetate buffer to amine residue of chitosan. All fractions showed high solubility at neutral pH. The chitosan hydrolysates exhibiting molecular weights between 30 and 41 kDa were considered to be most suitable as a food additive or functional agent as demonstrated by sensory evaluation. [source] Regioselective C-6 Hydrolysis of Methyl O -Benzoyl-pyranosides Catalysed by Candida Rugosa LipaseEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2009Aslan Esmurziev Abstract Hydrolysis of six methyl O -benzoyl-pyranosides has been investigated using Candida rugosa lipase in dioxane/buffer mixtures. The lipase catalysed the hydrolysis of all substrates in a regiospecific manner at C-6. The rate of reaction was dependent on pyranoside structure, reaction temperature and scale, dioxane concentration and agitation speed. Starting from their C-6 O -benzoyl precursors, the methyl 2,3,4-tri- O -benzoyl-pyranosides of ,- D -galactose, ,- D -galactose, ,- D -glucose, and methyl 2,3-di- O -benzoyl-,- D -galactopyranoside could be isolated in 85,96,% yield. In hydrolysis of methyl 2,3,4,6-tetra- O -benzoyl-,- D -glucopyranoside and methyl 2,3,4,6-tetra- O -benzoyl-,- D -galactopyranoside substrate inhibition were observed, which in part could be overcome by increasing the reaction volume. Methyl 2,3,4,6-tetra- O -benzoyl-,- D -glucopyranoside and methyl 2,3,4,6-tetra- O -benzoyl-,- D -mannopyranoside were poor substrates for Candida rugosa lipase and low degree of conversion towards products were obtained under all conditions. No acyl migration was detected in any of the products.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Esterification of n -butyric acid with n -butyl alcohol and transesterification of (R,,S)-phenylethanol by lipase immobilized on cellulose acetate,TiO2 gel fibreJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2002Yuko Ikeda Abstract Lipase (EC 3.1.1.3) was immobilized on cellulose acetate,TiO2 gel fibre by the sol,gel method. The immobilized lipases were used for esterification of n -butyric acid with n -butyl alcohol and enantioselective acylation of (R, S)-phenylethanol using vinyl acetate as an acyl donor. Compared with native lipase, the activity of the immobilized lipase was stable and relatively unaffected by the water content of the solvent and the substrate concentration. The data indicate that the lipases are immobilized on the fibre surface and that enzyme activity is influenced by bound water. However, the thermal reactivity and enantioselectivity of the immobilized lipase were less than those of native lipase. This may not reflect thermal inactivation of the enzyme but rather significant thermal contraction of the gel fibre by cellulose crystallization, resulting in liberation of bound water and a decrease in the amount of enzyme which is available for the reaction. Copyright © 2001 Society of Chemical Industry [source] The effect of an enzymatic pretreatment on the hydrolysis and size reduction of fat particles in slaughterhouse wastewaterJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2001L Masse Abstract The effect of an enzymatic pretreatment, Pancreatic Lipase 250 (PL-250), on the hydrolysis and size reduction of fat particles in slaughterhouse wastewater was characterised for enzyme doses ranging from 125 to 1000,mg,dm,3 and initial particle sizes (Din) varying between 53 and 383,µm. Treatment with PL-250 significantly reduced the size of pork fat particles in slaughterhouse wastewater. Particle size reduction increased with Din, possibly due to the more filamentous and plate-like configuration of the larger fat particles, which could be easily broken at weak points. The smaller particles were observed to be denser and more spherical. Size reduction also increased with enzyme concentration, but the benefit of adding more enzyme diminished greatly as enzyme dose was increased. The maximum long-chain fatty acid (LCFA) concentration in filtered samples was detected after 4,7,h of treatment and ranged from 8.2 to 34.9,mg,dm,3. The linear rate of LCFA released in solution during enzymatic pretreatment ranged from 39.4 to 169.9,mg,dm,3 d,1, and increased with enzyme concentration up to 500,mg,dm,3. At a PL-250 concentration of 1000,mg,dm,3, the LCFA release rate decreased, maybe due to excessive layering of adsorbed enzyme on the fat particles or increased degradation of released LCFAs. The pretreatment appeared to be more efficient with beef than pork fat particles. However, the effect of an enzymatic pretreatment on a downstream anaerobic treatment of slaughterhouse wastewater containing fat particles remains to be tested. © 2001 Society of Chemical Industry [source] THE DEGRADATION OF CHlTOSAN WITH THE AID OF LIPASE FROM RHIZOPUS JAPONICUS FOR THE PRODUCTION OF SOLUBLE CHlTOSANJOURNAL OF FOOD BIOCHEMISTRY, Issue 4 2001SEUNG S. SHIN ABSTRACT Lipase from Rhizopus japonicus degraded chitosan resulting in soluble chitosan hydrolysates with molecular weight of about 30,50 kDa as shown by size exclusion chromatography. Optimal temperature for the hydrolysis of chitosan was 40C. The chitosan degradation products were fractionated stepwise according to their molecular weights by ultrafiltration with the filtration range of over 0.1 ,m, 0. l ,m to 30 kDa, 30 kDa to 10 kDa, 10 to 3 kDa, and 3 to 0.2 kDa. These fractions exhibited molecular weights of 50, 41, 41, 35, and 30 kDa, respectively. The molecular weights did not coincide with the pore size of filter membranes. Chitosan hydrolysate exhibited almost the same structural composition in IR spectra as chitosan flakes, except the peak of 1550 nm,1 that appeared to be the COO residue shifted from sodium acetate buffer to amine residue of chitosan. All fractions showed high solubility at neutral pH. The chitosan hydrolysates exhibiting molecular weights between 30 and 41 kDa were considered to be most suitable as a food additive or functional agent as demonstrated by sensory evaluation. [source] Acceleration of Cheddar Cheese Lipolysis by Using Liposome-entrapped LipasesJOURNAL OF FOOD SCIENCE, Issue 2 2002E.E. Kheadr ABSTRACT: Two types of lipase (Palatase M and Lipase 50) were encapsulated in liposomes with trapping efficiencies of 35.9 and 40.3%, respectively. The lipases were incorporated into cheese milk at levels of 0.2, 0.5, and 1.0 lipase units/g fat. Treated cheeses had higher moisture and lower protein, fat, and ash contents than the control cheese and they were less firm, but more elastic and cohesive, than the control cheese. Production of free fatty acids was accelerated by the addition of encapsulated enzymes. Cheeses with up to 0.5 lipase unit/g milk fat had slightly better flavor intensities than control cheese. Cheeses with the highest level of Palatase M and Lipase 50 developed a pronounced soapy off-flavor after 2 and 3 mo of ripening, respectively. [source] Synthesis and specific biodegradation of novel polyesteramides containing amino acid residuesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2001Yujiang Fan Abstract Novel polyesteramides were synthesized from p -nitrophenyl esters of sebacic or adipic acids and diamines containing ,-amino acid ester groups. The optimal polymerization condition was 60 °C in N,N -dimethylformamide. The structures of these polymers were confirmed by IR and NMR. The number-average molecular weights of these polyesteramides ranged from 2280 to 23,600 (except for the polymers containing glycine residues), depending on the nature of the amino acid used. The biodegradability of the polyesteramides was investigated by in vitro hydrolysis with proteases and a lipase as catalysts in borate buffer solutions. The results indicated that the polymers containing L -phenylalanine were hydrolyzed most effectively by ,-chymotrypsin, subtilisin Carlsberg, and subtilisin BPN,. The polyesteramides containing other amino acid residues also underwent hydrolysis to different extents, reflecting the substrate specificity of the proteases. Lipase had almost no effect on the hydrolytic degradation of these polyesteramides. The polymers containing glycine residues were hardly decomposed by any of the enzymes used. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1318,1328, 2001 [source] In vitro comparative study of three pancreatic enzyme preparations: dissolution profiles, active enzyme release and acid stabilityALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2008A. ALOULOU Summary Background, Various pancreatic enzyme preparations are used for the treatment of pancreatic insufficiency but their bioequivalence is often unknown. Aim, To determine in vitro the pH-dependent release and acid resistance of enzymes from three commercially available pancreatin capsules, two containing enteric-coated (Creon 25000; Eurobiol 25000) and one uncoated (Eurobiol 12500) microspheres. Methods, Dissolution experiments were performed at pH values ranging from 4.0 to 5.8. Lipase, chymotrypsin and amylase activities were measured in the solution as a function of time. Results, Eurobiol 25000 started to release its enzymes significantly at pH 5.0 (t1/2 = 71 min), whereas the enzymes from Creon 25000 were only released at higher pH value (5.4; t1/2 = 49.2 min). Unlike chymotrypsin, lipase and amylase were highly sensitive to acidic conditions at the lowest pH values tested. Both enzymes were also found to be sensitive to proteolytic inactivation at the highest pH values tested. Overall, Eurobiol 25000 released higher amounts of active amylase and lipase than Creon 25000 at the pH values usually found in duodenal contents. The uncoated Eurobiol 12500 preparation was, however, the only one that could immediately release rather high levels of active chymotrypsin and lipase at low pH (4.5). Conclusion, These findings suggest that pH-sensitive enteric-coated pancreatin products containing similar amounts of enzymes might not be bioequivalent depending on the pH of duodenal contents. [source] Nano-Encapsulation of Lipase by Self-Assembled Nanogels: Induction of High Enzyme Activity and Thermal StabilizationMACROMOLECULAR BIOSCIENCE, Issue 4 2010Shin-ichi Sawada Abstract The effects of self-assembled polysaccharide nanogels on colloidal and thermal stability of lipase from Pseudomonas cepacia were investigated. The enzyme activity, especially kcat, drastically increased in the presence of nanogels of cholesterol-bearing pullulan (CHP). The thermostability of lipase complex increased because the denaturation temperature of lipase increased by more than 20,°C by complexation with CHP nanogels. Lipase denaturation and aggregation upon heating was effectively prevented by complexation with CHP nanogels. Moreover, complexation with CHP nanogels protected lipase from lyophilization-induced aggregation. Nano-encapsulation with CHP nanogel is a useful method for colloidal and thermal stabilization of unstable enzyme. [source] Electrospun Nanofibers Modified with Phospholipid Moieties for Enzyme ImmobilizationMACROMOLECULAR RAPID COMMUNICATIONS, Issue 16 2006Xiao-Jun Huang Abstract Summary: PANCMPCs containing phospholipid side moieties were electrospun into nanofibers with a mean diameter of 90 nm. Field emission SEM was used to characterize the morphologies of the nanofibers. These phospholipid-modified nanofibers were explored as supports for enzyme immobilization due to the characteristics of excellent biocompatibility, high surface/volume ratio, and porosity, which were beneficial to the catalytic efficiency and activity of immobilized enzymes. Lipase from Candida rugosa was immobilized on these nanofibers by adsorption. Preliminary results indicated that the properties of the immobilized lipase on these phospholipid-modified nanofibers were greatly promising. Schematic representation of the structure and electrostatic properties of phospholipid-modified nanofibers. [source] QSAR for Inhibition of Pseudomonas Species Lipase by 1-Acyloxy-3- N-n -octylcarbamyl-benzenesMOLECULAR INFORMATICS, Issue 3 2009Shyh-Ying Chiou Abstract 1-Acyloxy-3- N-n -octylcarbamyl-benzenes (1,9) are synthesized to characterize the Quantitative Structure,Activity Relationship (QSAR) for the Third Acyl Group Binding Site (TACS) of Pseudomonas species lipase. Inhibitors 1,9 are characterized as pseudo or alternate substrate inhibitors of the enzyme. The inhibition constant (Ki) and carbamylation constant (k2) for the enzyme inhibitions by inhibitors 1,9 are determined. The carbamate carbons of the n -octylcarbamyl moieties of inhibitors 1,9 are nucleophilically attacked by the active site serine of the enzyme and the n -octylcarbamyl groups of inhibitors 1,9 are bound to the Acyl Group Binding Site (ACS) of the enzyme. Both pKi and log,k2 values are linearly corrected with the Hansch hydrophobicity , values of the substituents of the acyl moieties of inhibitors 1,7. The slopes for these corrections are 0.13 and 0.02, respectively. This result suggests that the enzyme inhibitions by inhibitors 1,7 have a common mechanism. Thus, all acyl moieties of inhibitors 1,7 should bind to the TACS of the enzyme since the acyl and carbamyl moieties of inhibitors 1,7 are meta to each other. This result also indicates that the major interaction between the acyl moiety of inhibitors 1,7 and the TACS of the enzyme is primarily the hydrophobic interaction. The more hydrophobic characters of inhibitors 1,7 are, the more tightly these inhibitors bind to the enzyme. In contrast, 1-triphenylacetoxy-3- N-n -octylcarbamyl-benzene (8) and 1-trimethylacetoxy-3- N-n -octylcarbamyl-benzene (9) do not bind to the TACS of the enzyme due to the fact that the inhibitions by both inhibitors are not linearly correlated with ,. It is possible that these two inhibitors are too bulky to fit into the TACS of the enzyme. [source] Lipase catalyzed synthesis of ester-based surfactants from biomass derivativesBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 2 2008Sanjib Kumar Karmee Abstract Non-ionic surfactants find a unique place in pharmaceutical, detergent, food, and cosmetic industries because of their ready availability from biomass, low cost, and renewability. Generally these surfactants are esters obtained from the reaction of glycerol, L-ascorbic acid, and sugar, with long or medium chain fatty acids. Problems encountered during the synthesis of these surfactants are the immiscibility of highly polar substrates in organic solvents and non-regioselective reaction. Therefore, lipases as a catalyst and t -butanol or acetone, a mixture of solvent and ionic liquid as solvents, have been used for the synthesis of ester-based surfactants. This review focuses on the uses of lipases for the synthesis of surfactants obtained from biomass derivatives viz. fats and oils, sugar and vitamin-C. © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd [source] Characteristics of Immobilized Lipase on Hydrophobic Superparamagnetic Microspheres To Catalyze EsterificationBIOTECHNOLOGY PROGRESS, Issue 2 2004Zheng Guo A novel immobilized lipase (from Candida rugosa) on hydrophobic and superparamagnetic microspheres was prepared and used as a biocatalyst to catalyze esterification reactions in diverse solvents and reaction systems. The results showed that the immobilized lipase had over 2-fold higher activities in higher log P value solvents. An exponential increase of lipase activity against log P of two miscible solvent mixtures was observed for the first time. Both free and immobilized lipase achieved its maximum activity at the range of water activity ( aw) 0.5,0.8 or higher. At aw 0.6, the immobilized lipase exhibited markedly higher activities in heptane and a solvent-free system than did the native lipase. In multicompetitive reactions, the alcohol specificity of the lipase showed a strong chain-length dependency, and the immobilized enzyme exhibited more preference for a longer-chain alcohol, which is different from previous reports. The immobilized lipase showed higher specificities for butyric acid and the medium-chain-length fatty acids (C8,C12). Then, the immobilized lipase was extended to solvent-free synthesis of glycerides from glycerol and fatty acids. Recovered by magnetic separation, the immobilized lipase exhibited good reusability in repeated batch reaction, indicating its promising feature for biotechnology application. [source] A Novel Genetic Selection System for Improved Enantioselectivity of Bacillus subtilis Lipase ACHEMBIOCHEM, Issue 7 2008Ykelien L. Boersma Dr. Abstract In directed evolution experiments, success often depends on the efficacy of screening or selection methods. Genetic selections have proven to be extremely valuable for evolving enzymes with improved catalytic activity, improved stability, or with altered substrate specificity. In contrast, enantioselectivity is a difficult parameter to select for. In this study, we present a successful strategy that not only selects for catalytic activity, but for the first time also for enantioselectivity, as demonstrated by the selection of Bacillus subtilis lipase A variants with inverted and improved enantioselectivity. A lipase mutant library in an aspartate auxotroph Escherichia coli was plated on minimal medium that was supplemented with the aspartate ester of the desired enantiomer (S)-(+)-1,2- O -isopropylidene- sn -glycerol. To inhibit growth of less enantioselective variants, a covalently binding phosphonate ester of the opposite (R)-(,)-1,2- O -isopropylidene- sn -glycerol enantiomer was added as well. After three selection rounds in which the selection pressure was increased by raising the phosphonate ester concentration, a mutant was selected with an improved enantioselectivity increased from an ee of ,29.6,% (conversion 23.4,%) to an ee of +73.1,% (conversion 28.9,%) towards the (S)-(+)-enantiomer. Interestingly, its amino acid sequence showed that the acid of the catalytic triad had migrated to a position further along the loop that connects ,7 and ,E; this shows that the position of the catalytic acid is not necessarily conserved in this lipase. [source] Disulfiram is an Inhibitor of Human Purified Monoacylglycerol Lipase, the Enzyme Regulating 2-Arachidonoylglycerol SignalingCHEMBIOCHEM, Issue 11 2007Geoffray Labar Abstract Monoacylglycerol lipase (MAGL) is a key enzyme responsible for the termination of endocannabinoid signaling. Its crucial role in 2-arachidonoylglycerol (2-AG) metabolism, together with the numerous pharmacological properties mediated by this endocannabinoid, emphasize the interest in MAGL as therapeutic target, along with the need to design potent and selective inhibitors. Meanwhile, the complexity of 2-AG degradation pathways underscores the need to use a purified source of enzyme in evaluation studies of new inhibitors. We report here the first heterologous expression and purification of human MAGL. A highly pure protein was obtained and allowed us to measure the affinity of several MAGL inhibitors for the human enzyme. Importantly, disulfiram (tetraethylthiuram disulfide), a compound used to treat alcoholism, and other disulfide-containing compounds were shown to inhibit MAGL with good potency, likely through an interaction with cysteine residues. [source] Remote Interactions Explain the Unusual Regioselectivity of Lipase from Pseudomonas cepacia toward the Secondary Hydroxyl of 2,-DeoxynucleosidesCHEMBIOCHEM, Issue 4 2006Iván Lavandera Dr. Abstract Lipase from Pseudomonas cepacia (PCL) surprisingly favors acylation of the secondary hydroxyl at the 3,-position over the primary hydroxyl at the 5,-position in 2,-deoxynucleosides by up to >98:1. Catalytically productive tetrahedral intermediate analogues for both orientations were found by molecular modeling. However, acylation of the 3,-hydroxyl places the thymine base in the alternate hydrophobic pocket of PCL's substrate-binding site where it can hydrogen bond to the side-chain hydroxyls of Tyr23 and Tyr29 and the main chain carbonyl of Leu17. Conversely, acylation of the 5,-hydroxyl leaves the thymine base in the solvent where there is no favorable binding to the enzyme. We propose that these remote stabilizing interactions between the thymine base and PCL's substrate-binding site stabilize the 3,-acylation transition state and thus account for the unusual regioselectivity. [source] Exploring the Active-Site of a Rationally Redesigned Lipase for Catalysis of Michael-Type AdditionsCHEMBIOCHEM, Issue 2 2005Peter Carlqvist Abstract Michael-type additions of various thiols and ,,,-unsaturated carbonyl compounds were performed in organic solvent catalyzed by wild-type and a rationally redesigned mutant of Candida antarctica lipase B. The mutant lacks the nucleophilic serine 105 in the active-site; this results in a changed catalytic mechanism of the enzyme. The possibility of utilizing this mutant for Michael-type additions was initially explored by quantum-chemical calculations on the reaction between acrolein and methanethiol in a model system. The model system was constructed on the basis of docking and molecular-dynamics simulations and was designed to simulate the catalytic properties of the active site. The catalytic system was explored experimentally with a range of different substrates. The kcatvalues were found to be in the range of 10,3to 4 min,1, similar to the values obtained with aldolase antibodies. The enzyme proficiency was 107. Furthermore, the Michael-type reactions followed saturation kinetics and were confirmed to take place in the enzyme active site. [source] Production and Characteristics of an Enantioselective Lipase from Burkholderia sp.CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 2 2008GXU5 Abstract The lipase production of Burkholderia sp. GXU56 was influenced by carbon and nitrogen sources, inorganic salts, initial pH of the medium and cultivation temperature. The maximum lipase production was 580.52,U/mL and reached 5,times the level of the basic medium in the optimum medium at pH 8.0, 32,°C, 200,rpm and 40,48,h. The lipase was purified 53.6,fold to homogeneity and the molecular weight was 35,KDa on SDS-PAGE. The optimum pH and temperature of the lipase were 8.0 and 40,°C, respectively, and it was stable in the range of pH 7,8.5 and at temperatures below 45,°C. The lipase activity was strongly inhibited by Zn2+, Cu2+, Co2+, Fe2+, Fe3+ ions and SDS, while it was stimulated by Li+ and Ca2+ ions and in presence of 0.1,% CTAB, 0.1,% Triton X-100 and 10,% DMSO. Km and Vmax of the lipase were calculated to be 0.038,mmol/L, and 0.029,mmol/L min,1, respectively, with PNPB as the substrate. The GXU56 lipase showed enantioselective hydrolysis of (R,S)-methyl mandelate to (R)-mandelic acid, which is an important intermediate in the pharmaceutical industry. [source] Enzymatic Kinetic Resolution of Racemic 4-Tetrahydropyranols by Candida rugosa Lipase.CHEMINFORM, Issue 42 2007J. S. Yadav Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] An Efficient and Regiospecific Biocatalytic Esterification of Some Organic Acids Using Beef Pancreas Lipase (Bpl).CHEMINFORM, Issue 46 2006H. N. Roy Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Lyophilization of Lipase Together with Ionic Compounds Generates Highly Enantioselective and Solvent-Sensitive Lipase in Organic Solvents.CHEMINFORM, Issue 24 2005Shin-ichi Ueji Abstract For Abstract see ChemInform Abstract in Full Text. [source] Chemoenzymatic Synthesis of Enantiomerically Pure 1,2-Diols Employing Immobilized Lipase in the Ionic Liquid [bmim]PF6.CHEMINFORM, Issue 9 2005Ahmed Kamal Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: A Practical Enzymatic Method for Preparation of (S)-Ketoprofen with a Crude Candida rugosa Lipase.CHEMINFORM, Issue 6 2002Hui-Yuan Wu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Protein engineering and discovery of lipases,EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 1 2010Robert Kourist Abstract Lipases are widely used in the modification of fats and oils with applications in the production of structured triacylglycerols, selective isolation or incorporation of specific fatty acids, and in oleochemistry for the synthesis of emollient esters and sugar fatty acid esters. Despite the numerous examples for the effective use of lipases, the biocatalysts often need to be optimized to show the desired specificities, stability, operational properties, etc. Beside rather classical methods such as variation of the solvent system or carrier for immobilization, the use of protein engineering methods to modify the protein on a molecular level is an important tool for the creation of tailor-designed enzymes. Protein design is also complemented with the efficient isolation of novel lipases from the metagenome. This article covers concepts and examples for the discovery of novel lipases and their variants by protein engineering and metagenome techniques. [source] Enzymatic fatty acid exchange in glycero-phospholipids,EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 10 2003Patrick Adlercreutz Abstract Lipases can be used to exchange fatty acids in the sn -1 position of glycerophospholipids and phospholipase A2 is useful for the corresponding exchange reaction in the sn -2 position. In both cases, the exchange can be done in a one-step acidolysis process or in a two-step process. In the latter case, the original fatty acid in the desired position is removed by enzymatic hydrolysis or alcoholysis and after isolation of the resulting lysophospholipid, the new fatty acid is introduced, using the same enzyme, in an esterification reaction. Several synthesis examples from the literature are reviewed. Incorporation of a new fatty acid into the sn -1 position is more favourable than incorporation into the sn -2 position because of the magnitudes of the equilibrium constants of the reactions and because lipases can be used at much lower water activity than phospholipase A2. With the consecutive use of both enzymes highly pure products with defined fatty acids in both positions can be obtained. [source] Mutations towards enantioselectivity adversely affect secretion of Pseudomonas aeruginosa lipaseFEMS MICROBIOLOGY LETTERS, Issue 1 2008Sascha Hausmann Abstract Lipases are important biocatalysts used as detergent additives to manufacture biodiesel, and in particular, for the production of enantiopure compounds such as alcohols, amines and carboxylic acids. Extensive efforts were conducted trying to optimize lipase properties and lipase LipA of Pseudomonas aeruginosa comprises the best-studied example in terms of optimizing enantioselectivity by application of numerous directed evolution methods. Its enantioselectivity in the asymmetric hydrolysis of the model substrate 2-methyldecanoic acid p -nitrophenyl ester was increased from E=1.1 for the wild-type enzyme to E=51 for the best (S)-enantioselective variant which carried six amino acid exchanges. We have observed that overexpression of this variant in the homologous host resulted in only marginal yields of enzyme in the bacterial culture supernatant, suggesting that the enantioselective LipA variant was secreted with only low efficiency. Hence, we have analysed the secretion of this lipase variant and compared it to variants carrying either the respective single mutations or some combinations. We report here the identification of two amino acid substitutions located on the protein surface, which significantly impair lipase secretion. [source] New Monofunctionalized Fluorescein Derivatives for the Efficient High-Throughput Screening of Lipases and Esterases in Aqueous MediaHELVETICA CHIMICA ACTA, Issue 3 2006Yongzheng Yang Abstract Monoalkylation or acylation of fluorescein (1) with various acyloxymethyl or acyl halides afforded, respectively, a series of ether- (2) and ester-functionalized (3) fluorogenic probes. The highly reactive and water-soluble substrates release fluorescein (1) upon reaction with lipases and esterases within seconds or minutes, both under fully aqueous conditions or in the presence of DMSO (20%) as a co-solvent. The most-reactive substrates in the two series were the octanoic acid derivatives 2f (=,2-{6-[(octanoyloxy)methoxy]-3-oxo-3H -xanthen-9-yl}benzoic acid) and 3a (=,2-[6-(octanoyloxy)-3-oxo-3H -xanthen-9-yl]benzoic acid). Esterases were found to generally react faster under aqueous conditions, while lipases were more reactive in the presence of DMSO as a co-solvent. [source] Second Generation Sol-Gel Encapsulated Lipases: Robust Heterogeneous BiocatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6-7 2003Manfred Abstract The original procedure for the encapsulation of lipases in sol-gel materials produced by the fluoride-catalyzed hydrolysis of mixtures of RSi(OCH3)3 and Si(OCH3)4 has been improved considerably. This involves higher enzyme loading, variation of the alkylsilane precursor, and the use of additives such as isopropyl alcohol, 18-crown-6, Tween,80®, methyl-,-cyclodextrin and/or KCl. A dramatic increase in enzyme activity is observed. The sol-gel lipase immobilizates are also excellent catalysts in the kinetic resolution of chiral alcohols and amines, recycling without any substantial loss in enantioselectivity and a residual activity of 70% being possible even after 20 reaction cycles. [source] ROLE OF SATURATED FATTY ACIDS IN LIPASE PRODUCTION , USING PSEUDOMONAS AERUGINOSAJOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2007A.N. SARAVANAN ABSTRACT Complex substrates always induce substantial amount of enzyme production during hydrolysis by microorganisms. In this study, ghee was taken for its saturated fatty acid content and analyzed as an inducer for the production of lipase. With ghee emulsion, the bacterium Pseudomonas aeruginosa at optimal condition produced 60 units/min/L at 72 h. With olive oil emulsion, this organism produced only 41 units/min/L as maximum at 96 h. The saturated fatty acids present in ghee make it a hard substance for hydrolysis, which is the reason for the increased enzyme production. This was evaluated by the iodine number experiment. Ghee can also reduce the production cost whereas the costlier olive oil constitutes 25,50% of the total production cost for a commercial scale. The experimental results showed that the saturated fatty acids play an important role in lipase enzyme induction by P. aeruginosa. The use of ghee is cost-effective; hence, it can be used as a potential inducer for lipase production. PRACTICAL APPLICATIONS Lipases are industrially very important enzymes. They are used in pharmaceutical, food, soap and other industries. In lipase production, olive oil is the main constituent. Comparatively, olive oil is costlier; hence, it increases the production cost of lipase. So, this study was done to replace olive oil with a much cheaper ghee using Pseudomonas aeruginosa. The ghee-containing medium gave a very good result because of the presence of complex saturated fatty acids. The ghee-containing medium produced 60 units/min/L at 72 h. The olive oil medium, which contains mainly unsaturated fatty acids, produced only 41 units/min/L as maximum at 96 h. Hence, in the commercial scale, ghee can reduce raw material cost as well as operation time cost significantly when it is used as substrate. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||