The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Uwe T Bornscheuer - One of the best experts on this subject based on the ideXlab platform.
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the short form of the recombinant cal a type Lipase um03410 from the smut fungus ustilago maydis exhibits an inherent trans fatty acid selectivity
Applied Microbiology and Biotechnology, 2012Co-Authors: Henrike Brundiek, Stefan Sas, Andrew Evitt, Robert Kourist, Uwe T BornscheuerAbstract:The Ustilago maydis Lipase UM03410 belongs to the mostly unexplored Candida antarctica Lipase (CAL-A) subfamily. The two Lipases with […] the highest identity are a Lipase from Sporisorium reilianum and the prototypic CAL-A. In contrast to the other CAL-A-type Lipases, this hypothetical U. maydis Lipase is annotated to possess a prolonged N-terminus of unknown function. Here, we show for the first time the recombinant expression of two versions of Lipase UM03410: the full-length form (lipUMf) and an N-terminally truncated form (lipUMs). For comparison to the prototype, the expression of recombinant CAL-A in E. coli was investigated. Although both forms of Lipase UM03410 could be expressed functionally in E. coli, the N-terminally truncated form (lipUMs) demonstrated significantly higher activities towards p-nitrophenyl esters. The functional expression of the N-terminally truncated Lipase was further optimized by the appropriate choice of the E. coli strain, lowering the cultivation temperature to 20 °C and enrichment of the cultivation medium with glucose. Primary characteristics of the recombinant Lipase are its pH optimum in the range of 6.5–7.0 and its temperature optimum at 55 °C. As is typical for Lipases, lipUM03410 shows preference for long chain fatty acid esters with myristic acid ester (C14:0 ester) being the most preferred one. More importantly, lipUMs exhibits an inherent preference for C18:1Δ9 trans and C18:1Δ11 trans-fatty acid esters similar to CAL-A. Therefore, the short form of this U. maydis Lipase is the only other currently known Lipase with a distinct trans-fatty acid selectivity.
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activity and stability of Lipase in the solid phase glycerolysis of triolein
Enzyme and Microbial Technology, 1994Co-Authors: Uwe T Bornscheuer, Tsuneo YamaneAbstract:Abstract Lipase-catalyzed glycerolysis of triolein was studied in a solid-phase system. The activity and stability of three bacterial Lipases in crude and purified forms were examined. Most of these Lipases were suitable for the high-yield synthesis of monooleylglycerol. With crude Lipase from Chromobacterium viscosum , 96% monooleylglycerol concentration was achieved. In the case of pure Lipase from Pseudomonas cepacia , immobilization on Celite was necessary. This led to a strong increase in the long-term stability and final monooleylglycerol concentration. Immobilization on Sepharose™ led to less stable and active Lipases from P. cepacia . In general, the highest loss in stability was observed in the first reaction hour, and purified Lipases were less suitable. Furthermore, six yeast and mold Lipases were employed as catalysts in the model reaction system. Most of them have been neither very stable nor very active in the glycerolysis reaction. Only purified Lipase from Rhizopus delemar gave moderate monooleylglycerol concentrations. The addition of R. delemar at intervals influenced neither stability nor monooleylglycerol concentrations. The optimum cooling temperature for the solidification of the reaction mixture, which was necessary for high monooleylglycerol concentration, was determined to be 8°C.
Aran Hkittikun - One of the best experts on this subject based on the ideXlab platform.
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mixed Lipases for efficient enzymatic synthesis of biodiesel from used palm oil and ethanol in a solvent free system
Journal of Molecular Catalysis B-enzymatic, 2010Co-Authors: Ketsara Tongboriboon, Benjamas Cheirsilp, Aran HkittikunAbstract:The enzymatic synthesis of biodiesel from used palm oil and ethanol using immobilized Lipases in a solvent-free system was attempted. Five immobilized Lipases, Lipase AK from Pseudomonas fluorescens, Lipase PS from Pseudomonas cepacia, Lipase AY from Candida rugosa, Lipozyme TL IM from Thermomyces lanuginosa and Novozym 435 from Candida antarctica, were screened based on their catalytic activities on reactions involved in biodiesel synthesis. The combined use of Lipase AY and Lipase AK gave a higher yield of biodiesel than using Lipase AK alone. The optimal conditions for biodiesel synthesis using mixed Lipases in a batch system were: 2% water content, 10% enzyme dosage and 3:1 molar ratio of ethanol to oil. The mixed Lipases could be used in 15 replicates with retained relative activity higher than 50%. In a continuous system using mixed Lipases packed in packed-bed reactor, >67% of biodiesel was achieved.
Patrick Adlercreutz - One of the best experts on this subject based on the ideXlab platform.
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immobilisation and application of Lipases in organic media
Chemical Society Reviews, 2013Co-Authors: Patrick AdlercreutzAbstract:Different methods of preparing Lipases for use in organic media are critically reviewed. Solid Lipase preparations can be made by typical immobilisation methods such as adsorption, entrapment, covalent coupling or cross-linking. Immobilisation is especially attractive for Lipases because, in addition to the normal benefits of enzyme immobilisation, it can also lead to a considerable increase in catalytic activity, probably caused by conformational changes in the Lipase molecules. Activation can be achieved, for example, using hydrophobic support materials or surfactants during the immobilisation procedure. Surfactants can also be used to solubilise Lipases in organic media via the formation of hydrophobic ion pairs, surfactant-coated Lipase or reversed micelles. Lipase preparation methods are discussed with regard to potential Lipase inactivation and activation effects, mass transfer limitations, Lipase stability and other features important for applications. The practical applications of Lipases in organic media reviewed include ester synthesis, modification of triacylglycerols and phospholipids, fatty acid enrichment, enantiomer resolution, biodiesel production and acylation of carbohydrates and bioactive compounds.
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Vernonia Lipase : A plant Lipase with strong fatty acid selectivity
Methods in Enzymology, 1997Co-Authors: Patrick Adlercreutz, Thomas Gitlesen, Ignatious Ncube, John S. ReadAbstract:Publisher Summary Lipases are useful tools in lipid processing. One important advantage of Lipase-catalyzed processing compared to chemical methods is the inherent selectivity of the enzymatic reactions. It has been shown that some plant seeds contain Lipases that show selectivity for the most common fatty acids in that particular kind of seed. It can thus be of interest to study Lipases from plant seeds that contain unusual fatty acids. This chapter describes a Lipase from seed of Vernonia galamensis . These seeds contain about 40% oil and the oil contains up to 80% vernolic acid. Much of the vernolic acid is present in the form of trivernolin. The chapter describes the purification and properties of the Lipase as well as purification and properties of trivernolin and vernolic acid, which are used in the studies of the fatty acid selectivity of the Lipase.
Giacomo Carrea - One of the best experts on this subject based on the ideXlab platform.
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the lid is a structural and functional determinant of Lipase activity and selectivity
Journal of Molecular Catalysis B-enzymatic, 2006Co-Authors: Francesco Secundo, Karl-erich Jaeger, Giacomo Carrea, Chiara Tarabiono, Pietro Gattilafranconi, Stefania Brocca, Marina Lotti, Michael Puls, Thorsten EggertAbstract:In several Lipases access to the enzyme active site is regulated by the position of a mobile structure named the lid. The role of this region in modulating Lipase function is reviewed in this paper analysing the results obtained with three different recombinant Lipases modified in the lid sequence: Candida rugosa Lipase isoform 1 (CRL1), Pseudomonas fragi Lipase (PFL) and Bacillus subtilis Lipase A (BSLA). A CRL chimera enzyme obtained by replacing its lid with that of another C. rugosa Lipase isoform (CRL1LID3) was found to be affected in both activity and enantioselectivity in organic solvent. Variants of the PFL protein in which three polar lid residues were replaced with amino acids strictly conserved in homologous Lipases displayed altered chain length preference profile and increased thermostability. On the other hand, insertion of lid structures from structurally homologous enzymes into BSLA, a Lipase that naturally does not possess such a lid structure, caused a reduction in the enzyme activity and an altered substrate specificity. These results strongly support the concept that the lid plays an important role in modulating not only activity but also specifity, enantioselectivity and stability of Lipase enzymes.
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Lipase activity and conformation in neat organic solvents
Journal of Molecular Catalysis B-enzymatic, 2002Co-Authors: Francesco Secundo, Giacomo CarreaAbstract:The methods commonly employed to improve the catalytic efficiency and to determine the conformation of Lipases in organic solvents are briefly examined and discussed. Special attention is dedicated to the properties of different formulations of Lipase from Pseudomonas cepacia (Lipase PC) and Lipase B from Candida antarctica (CALB). Non-covalent Lipases/PEG complexes are particulary interesting because they are easy to prepare, very active and soluble in suitable organic solvents. This last property makes it possible to carry out conformational studies of Lipases by circular dichroism and intrinsic protein fluorescence. Moreover, correlations between enzyme activity and solubility in organic solvents, shed light on the effects of diffusional limitations and Lipase conformational changes on the catalytic efficiency of enzymes in organic solvents.
Maarten R Egmond - One of the best experts on this subject based on the ideXlab platform.
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cloning purification and characterisation of staphylococcus warneri Lipase 2
Biochimica et Biophysica Acta, 2001Co-Authors: M Van Kampen, R Rosenstein, Friedrich Gotz, Maarten R EgmondAbstract:A gene encoding an extracellular Lipase was identified in Staphylococcus warneri 863. The deduced Lipase is organised as a prepro-protein and has significant similarity to other staphylococcal Lipases. The mature part of the Lipase was expressed with an N-terminal histidine tag in Escherichia coli, purified and biochemically characterised. The results show that the purified Lipase (named SWL2) combines the properties of the staphylococcal Lipases characterised so far. It has both a high preference for short chain substrates and surprisingly, it also displays phosphoLipase activity. Homology alignment was used to analyse sequence–function relationships of the staphylococcal Lipase family with the aim to identify the structural basis underlying the different properties of the staphylococcal Lipases.
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Cloning, purification and characterisation of the Lipase from Staphylococcus epidermidis--comparison of the substrate selectivity with those of other microbial Lipases.
European journal of biochemistry, 1998Co-Authors: Jan-willem F. A. Simons, Friedrich Gotz, Maarten R Egmond, Muriel D. Van Kampen, Sabine Riel, Hubertus M. VerheijAbstract:On the chromosome of Staphylococcus epidermidis RP62A the Lipase gene (gehSE1) is immediately flanked by the icaAA'BC operon, which is involved in biofilm formation. Since Lipase production might play a role in staphylococcal skin colonisation as well, we studied the biochemical properties of the staphylococcal Lipases more closely. The DNA sequence and the deduced protein sequence revealed that gehSE1 is very similar to the Lipase sequence of S. epidermidis strain 9. Like other staphylococcal Lipases, gehSE1 is organised as a preproenzyme. The part of gehSE1 coding for the mature Lipase was cloned and overexpressed as a fusion protein with an N-terminal histidine tag in Escherichia coli. The Lipase was purified to homogeneity using a combination of precipitation techniques, metal-affinity chromatography and gel filtration. Biochemical characterisation showed that this Lipase is closely related to the Lipase from Staphylococcus aurelis NCTC8530. Both enzymes have a pH optimum around 6, are very stable at low pH, and need calcium as a cofactor for catalytic activity. The preferred substrates are small triacylglycerols, with a maximum activity toward tributyrylglycerol. Comparison of the substrate selectivity with those of other microbial Lipases showed that phospholipids are generally poor substrates for Lipases. An exception is the Lipase from Staphylococcus hyicus, which prefers phospholipids as a substrate, distinguishing this staphylococcal Lipase from other microbial Lipases. These results are discussed in view of the structure/function relationships of staphylococcal Lipases, and the possible involvement of these enzymes in biological processes such as skin colonisation and pathogenesis.
