Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 18

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

Search:
in the keywords:  LIPASE
help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1

Trends and perspectives of lipases applications

100%
Pilarek M., Szewczyk K. W., Wrona M.
Biotechnologia
|
2002
|
issue 2
146-164
EN
Properties of microbial lipases important in practical applications are briefly described. Applications of lipases in wide branches of industry are presented. Potential fields of lipases applications are also discussed.
2

Nonaqueous media ? site of enzymatic catalysis

100%
Bancerz R., Ginalska G.
Biotechnologia
|
2009
|
issue 4
168-182
EN
Lipases, esterases, acylases, glycosidases, aldolases are the most used enzymes in synthetic organic chemistry. Among the biocatalysts, lipases are the most frequently used. This class of enzymes is able to catalyze the hydrolysis of carboxylic acid esters in aqueous medium on the reverse reaction in organic solvents. The use of enzymes in organic solvents is now well established and there are several advantages of conducting enzymatic reaction in water poor media such as increased solubility of hydrophobic substrates, shifting of thermodynamic equilibrium in favour of synthesis over hydrolysis and increased thermostability of the enzyme. However, the practical application of enzyme in organic solvents has been hampered by the low catalytic activities compared to those expressed in water. This review highlights recent research on the stabilization of enzymes using both chemical and biological means to increase the lifetime o the biocatalyst.
3

Lipases - tool in oils and fats biotechnology

100%
Adamczak M., Bednarski W.
|
EN
Lipases (acylglycerol hydrolases EC 3.1.1.3) comprise a group of enzymes of widespread occurrence.Their biological function is to catalyse the hydrolise of triacylglycerols to give free fatty acids, diacylglycerols, monoglycerols and glycerol.This reaction is riverisble, so that the enzymes also catalyse the formation of acylglycerols.A feature whih differs lipases from other enzymes is their activity on water-insoluble substrates, at oil-water interface. Interest in lipases from different sources, in particular from microorganisms, has markedly incresed in the last decade due to the potential application of lipases in food industry, chemical industry, chemistry, biochemistry and medicine.
4

Role of lipases in human metabolism

100%
Sadurska B., Skalska-Hilgier S.-H. E., Skalska-Hilgier E.
|
|
vol. 55
|
issue 4
541-563
EN
Lipases play a crucial role in the metabolism of lipids in humans. These enzymes can be classified according to the location: located in the digestive juices (lingual lipase, gastric lipase and pancreatic lipase), located intracellularly (hormone-sensitive lipase and lysosomal acid lipase) and in the endothelial cells (lipoprotein lipase and hepatic lipase). In this review, we discuss the interrelationships of lipases, their structure in humans, how they are affected by hormones and the clinical aspects of their deficiency.
5

Lipases: resources, structure and catalytic properties

100%
Antczak T., Graczyk J.
Biotechnologia
|
2002
|
issue 2
130-145
EN
Properties of lipases, which not only hydrolyze lipids in aqueous solutions, but are also active in nonaqueous systems, have attracted interest of many researchers. The presented dissertation contains a review of publications devoted to synthesis and classification of microbial lipases, both intra- and extracellular ones. Types of reactions catalyzed by these enzymes, their specificity, mechanism of reaction, molecular background of the interfacial activation, and an influence of the reaction medium on their properties are discussed.
6

Mathematical modelling of esters synthesis catalyzed by Mucor javanicus lipase in non water environment

80%
Antczak T., Galas E.
Biotechnologia
|
1997
|
issue 3
121-133
EN
A mathematical model describing esters synthesis catalysed by lipase from Mucor jawanicus was designed.This model was confirmed by the syntheses of propyl stearate, butyl stearate and oleyl stearate catalysed by M.javanicus lipase.Using this model it is possible to estimate the maximum achievable yield of ester synthesis.The model can also applied for performing simulation to evaluate the effect of particular elements on the yield of ester synthesis and, consequently, it could enable the optimum selection of particular elements of the reaction system.
7

Partial characterization of a lipase from gypsy moth (Lymantria dispar L.) larval midgut

80%
Mrdakovic M., Lazarevic J., Peric_Mataruga V., Ilijin L., Vlahovic M.
Folia Biologica
|
2008
|
vol. 56
|
issue 1-2
103-110
EN
Lipase activity of the gypsy moth (Lymantria dispar L.) was studied by the spectrophotometric method using crude homogenate of fifth-instar larval midgut tissues as the enzyme source and p-nitrophenyl caprylate (pNPC) as substrate. A Km value of 0.310mM and a Vmax value of 1.479U/mg prot. were obtained for this substrate. Among various p-nitrophenyl esters tested, maximum activity was obtained for p-nitrophenyl caprylate and p-nitrophenyl caprate. The enzyme was most active at alkaline pH, with maximum at pH 8.2. Decreased activity was detected after preincubation in buffers of pH below 7.0 and above 8.2. The enzyme was unstable at room temperature. The enzyme was Ca2+ independent. Its activity was inhibited by PMSF, Fe2+, Ag+ and Pb2+, while Fe3+ inhibited enzyme activity by about 40%.
8

Biotechnological methods of synthesis of biosurfactants Part I. Enzymatic synthesis of surfactants

80%
Bednarski W.
Biotechnologia
|
1999
|
issue 4
7-23
EN
Surface active agents (surfactants) are generally amphiphilic substances consisting of hydrophobic and hydrophilic moieties. They have many applications in the food, cosmetics, and pharmaceutical industry, pollution control, etc. Lipases (EC 3.1.1.3; acyloglycerol hydrolase) have many applications and they are able to catalyze synthesis of biosurfactants ie. mono- and diacyloglycerols, carbohydrate esters of fatty acids etc. These products are biodegradable, natural, non-toxic and aceptable by consumers. In this article enzymatic methods of synthesis of biosurfactants are presented.
9

Intensification of lipase biosynthesis as a result of electrofusion of Rhizopus cohnii protoplasts

80%
Sawicka-Zukowska R., Juszczakiewicz D., Misiewicz A., Krakowiak A., Jedrychowska B.
Journal of Applied Genetics
|
2004
|
vol. 45
|
issue 1
37-48
EN
Our objective was to obtain products of fusion of the filamentous fungus Rhizopus cohnii Rh.c./1 with an increased capacity for lipase biosynthesis in comparison with the original strain. Protoplasts of auxotrophic mutants of the parent strain Rh.c./1 obtained after UV irradiation of the spores were subjected to electrofusion. We found that the largest number of electrofusion products could be obtained with the use of the following process parameters: 1 or 2 impulses immediately following one another with a field intensity of 200 V/cm and an exposition time of 1000 ms at the stage of dielectrophoresis, 1 impulse with a field intensity of 500 V/cm and an exposition time of 10 ms or 20 ms at the stage of fusion, regulated temperature of 4oC before and after the process, rounding time of ca 20 min. Electrofusion of protoplasts of auxotrophic mutants of the Rh.c./1 strain produced 19 fusion products whose lipase biosynthesis capacity in a liquid medium culture was higher than that of the parent strains. The fusion product labelled XIII-21 was selected as the best strain. Lipase activity obtained after its culture in the liquid medium was ca 3.5 times higher than that obtained after the culture of the original strain Rh.c./1.
10

Enzymatic hydrolysis of waste fats

80%
Antczak T., Krystynowicz A., Galas E.
Biotechnologia
|
2000
|
issue 2
120-130
EN
The intracellular lipases of Mucor circinelloides and Mucor racemosus immobilised in situ as well as the extracellular lipase of Rhizopus nigricans in soluble form were applied to enzymatic hydrolysis of waste fats from oil and meat industry, waste sludge of fats from municipal and industrial sewage-treatment plants and waste water containing microemulsion of fats. The reaction of hydrolysis of plant and animal waste fats was carried out by two methods. The first one was a partial hydrolysis of acylglycerols to obtain mono- and diacylglycerols. The second variant was complete hydrolysis of fats to obtain glycerol and free fatty acids. It has been demonstrated that lipase of Rhizopus nigricans partly hydrolysed waste fats. The products of hydrolysis contained 35-45% mono- and diacylglycerols. These products may be used as emulsifier in the hydrolysis of fats. The yield of hydrolysis of waste fats by immobilised Mucor lipases was from 85 up to over 95%. Waste sludge of fats from municipal and industrial sewage contain 12-62% of free fatty acids. This kind of material was hydrolysed without an emulsifier but with the addition of calcium chloride. The yield of hydrolysis of acylglycerols was from 45 to 76%. The yield of hydrolysis of microemulsion of fats in waste water by immobilised Mucor lipases was from 80 up to over 95%. As the hydrolysis products contained free fatty acids, mono- and diacylglycerols, it was easy to make emulsions which could be utilised in anaerobic-aerobic processes.
11

Purification and some characteristics of Penicillium citrinum lipase

80%
Maliszewska I. H.
Biotechnologia
|
1997
|
issue 3
109-120
EN
An extracellular lipase (glycerol ester hydrolases E.C. 3.1.1.3.) was isolated from a culture filtrate of Penicillium citrinum. The purification procedure included ammonium sulfate precipitation, ultrafiltration and chromatography on Octyl-Sepharose CL-4B. The enzyme was 400-fold purified with 9.66% yield. The molecular weight has been estimated by polyacrylamide gel electrophoresis under denaturing conditions at 26000. On the other hand, lipase forms active dimers and tetramers aggregates as observed after native PAGE. Lipase from Penicillium citrinum showed a preference for triacylglycerols. It is non-specific and hydrolyzes each of the three ester bonds of triacylglycerols. The enzyme showed a maximum activity at pH 7.2 at 30 oC and was stable in the range of pH 6.0-7.5 and the temperature of 10oC - 40oC.
12

The influence of reaction conditions on synthesis of esters by Mucor javanicus T45 lipase

80%
Antczak T., Hiler D., Galas E.
Biotechnologia
|
1993
|
issue 1
59-67
EN
The effect of reaction milieu on synthesis of esters of higher fatty acids by Mucor javanicus T45 lipase was investigated. The folloving factors were studied: a temperature, an organic solvent, concentrations of substrates and their molar ratios, a solvent concentration, pH of water present in the lipase preparation and a concentration of diethanoloamine (DEtA) applied to modifity the essential water layer of the enzyme. It was revelated that M. javanicus lipase, immobilized in situ in its mycelium, preserves from 48 to 92 percent of the initial activity after heating for 1 houer at 100oC in nonpolar solvents. The modification of the enzyme essential water layer with DEtA increases the synthetic activity of the enzyme by about 70 percent.
13

Mathematical modelling of sugar esters synthesis catalyzed by Mucor circinelloides lipase in non water environment

70%
Antczak T., Krystynowicz A., Hiler D., Bielecki S., Galas E.
Biotechnologia
|
1999
|
issue 1
153-163
EN
A mathematical model describing sucrose esters synthesis in biphasic di-n-phentyl ether - water system by lipase from Mucor circinelloides has been elaborated. This model considers correlation between physicochemical factors, dependent on the solvent, substrates, products and temperature, catalytic factors corresponding to the relationship between lipase and the physicochemical factors of the model (Ko=F(A)), as well quantitative factors whose values may be regulated during the reaction (substrate concentration, phase volume coefficient (A) and water concentration). This model was confirmed by syntheses of caprylic and oleic sucrose esters. The maximum reaction yield for the synthesis of caprylic sucrose ester calculated on the basis of the elaborated model was 67,5% and experimental value was 67,8% for A = 44. For oleic sucrose ester, the theoretical and experimental yields of synthesis, were 71,9% and 70,5% respectively. Using this model it is possible to estimate the maximum achievable (in particular conditions) yield of the ester synthesis. It can also be applied for simulations enabling evaluation of the effect of the particular factors on the yield of ester synthesis and resulting optimisation of selected factors in the reaction system. The simulations were performed for two factors of the model in three dimensional space. It was found that the ester synthesis was mostly affected by the following invariable factors: partition coefficients of products (PE, PW) and phase volume coefficient (A). The concentration of water in the water phase and the partition coefficients of sugar (PAL) influenced the yield to a smaller extent.
14

Biodiesel obtained by microbiological methods

70%
Bialecka-Florjanczk., Stolarzewicz I., Kucharski D.
Biotechnologia
|
2009
|
issue 4
74-87
EN
Biodiesel ? a fuel for diesel engines ? represents an alternative environment-friendly source of energy obtained from renewable materials. Biodiesel is produced in triacylglycerol transesterification by alcohols such as methanol or ethanol and comprises fatty acid methyl and ethyl esters. For ecological reasons, the enzymatic transesterification is becoming of increasing interest, yet high price of enzymes obstructs its full industrial application. This work presents the latest achievements in biodiesel enzymatic production that refer both to isolated lipases as well as microorganisms that synthesize these enzymes. In the latter case, the work focuses on methods that allow for increasing biocatalyst activity and stability through changes in microorganism culture conditions, their immobilization and application of genetic engineering techniques.
15

Selected issues of non-conventional enzymology. Part II ? Characterization of reaction media and biocatalysts applied in non-conventional enzymology

70%
Antczak T., Szczesna-Antczak M.
|
2003
|
issue 3
139-158
EN
Burgeoning scientific literature proves that enzymes can catalyze chemical reactions in non-conventional media, are active against liquid, solid or gaseous substrates, retain their catalytic function in organic solvents, biphasic systems composed of organic solvent and water and supercritical fluids. Non-aqueous media appeared to be a promising alternative as an environment for the reactions catalyzed by enzymes. The possibility of carrying out enzymatic processes in such unusual milieus enlarged the range of applications of biocatalysis, and solved many problems witnessed by pharmaceutical, food and chemical industries. The paper describes both advantages and disadvantages of non-conventional media, and presents the examples of practical uses of selected enzymes (lipases, proteases, oxidoreductases, glycosidases) in these systems. The details on medium composition and the form of the biocatalyst are included.
16

Encapsulation of immobilised in situ intracellurar lipases of Mucor

61%
Antczak T., Bugla J., Szeja W., Galas E.
Biotechnologia
|
1999
|
issue 1
172-179
EN
Endolipases associated with the cell structures of microorganisms are more active in comparison with purified enzymes. Due to the weak mechanical resistance lipases immobilised in situ cannot be used many times. The method of lipases encapsulation in polysacharides hydrophilic gels was elaborated. The lipases Mucor immobilised in situ were treated with oleic acid in hexane and then dispersed in an aqueous solution of sodium alginate or karagenate. Immobilisation of enzymes was achieved by intermolecular cross-linking of the polysacharide chains using the solution of calcium or potassium salts. The biocatalysts prepared under proposed conditions were active in hydrolysis of esters, as well as in esterification reaction. It was found that immobilised enzymes were active for a long time, were mechanically resistant and could be used many times in periodic and continuous processes.
17

Enzymatic modification of natural triacylglycerols and the properties of the obtained products

61%
Adamczak M.
Biotechnologia
|
2005
|
issue 1
131-151
EN
Structured triacylglycerols (sTAG) are chemical compounds with a precisely defined chemical and stereochemical structure whose natural nutritional and physico-chemical properties have been modified. Modified TAG can be synthesized with the application of genetic engineering, physical, chemical and enzymatic methods. Due to the demand for the precisely determined structure of the resulting sTAG, their synthesis with the use of lipases is preferred. Prepared pure fatty acids or their esters, as well as synthetic monoacid triacylglycerols are necessary for sTAG synthesis. The use of such unnatural substrates requires additional processes and is cost consuming. Additionally, it can lead to loss of valuable components present in natural oils and contribute to a decrease in the oxidative stability of the resulting products. The application of naturally occurring fats or oils can considerably simplify sTAG synthesis and reduce the costs of the processes. Recently, much attention has been paid to an assessment of nutritional properties of structured triacylglycerols or acylglycerols. The aim of this article is to present the methods of sTAG synthesis, including examples of the use of naturally occurring triacylglycerols as substrates.
18

Entrapment of immobilised in situ intracellular lipase of Mucor in microporous capsules

61%
Antczak T., Bugla J., Mastalerz M., Niemiec A., Szeja W., Slek M., Galas E.
Biotechnologia
|
2000
|
issue 4
142-151
EN
Lipases Mucor circinelloides and Mucor racemosus immobilised in situ were closed in microporous polysacharides hydrophilic gel cross-linked using a solution of calcium salts. In order to increase the porosity of polysacharides matrix during its cross-linking oligomer molecules of ethylene oxide (optimal Polikol 1000) were incorporated in the structure of the matrix. Then the oligomer was removed by acetone extraction. The obtained biocatalyst preparations were tested in hydrolysis of esters and esterification of oleic acid with butanol. The hydrolysis was carried out in water saturated organic solvents medium (n-hexane and diisopropylether). It was found that the efficiency of M. racemosus lipase immobilisation in hydrolysis of n-butyl oleate, n-butyl palmitate, n-butyl stearate, n-butyl laurate amounted to 60%. The efficiency of M. circinelloides lipase immobilisation in esterification of oleic acid with 1-butanol in hexane achieved 45%.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.