Now showing items 1-20 of 4590

    • PROBING THE INTERACTION OF PHOSPHOLIPASE A2 AND PHOSPHOLIPIDS WITH RECOMBINANT DNA TECHNIQUES

      Verheij, H. M.; Department of Biochemistry , University of Utrecht, CBLE, University Center De Uithof, P.O. Box 80054, 3508 TB Utrecht (The Netherlands) (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      The primary structure of eighty phospholipases A> from different sources is known. These sequences reveal a high degree of homology, and aboutthirty percent ofall residuesis fully conserved. In addition about twentyfive percentof the aminoacids is substituted by amino acids with similar properties like charge and/or polarity and hydrogen-bonding capacity. The use of recombinant DNAtechniques has proovento be a powerful techniqueto study the role of amino acid side chains in porcine pancreatic phospholipase Ap. The application of these techniques has madeit possible to create a deletion mutant with enhanced activity and improved crystallisation properties. It was shown that Leu-31 is important for the orientation of the substrate molecule and is probably also importantfor the shielding of the active site from excess water. Tyr- 69 was shownto be involved in the orientation of the substrate molecule through an interaction with the phosphate group ofthe substrate. A numberof absolute conserved residues like Tyr-52 and Tyr-73 are important for folding and/or stability of the protein. Theresults of the studies described here support the mechanism of catalysis of phospholipase A2 that was proposed already ten years ago.
    • Human Lipoprotein Lipase: Important Roles Of A Specific N-Linked Glycosylation Site And Specific Serines In Secretion And Enzyme Activity

      Chan, Lawrence; Faustinella, Fabrizia; Semenkovich, Clay F.; Smith, Louis C.; Baylor College of Medicine, Houston Texas 77030 (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      Thestructure-function relationship of human lipoprotein lipase was studied by expressionof the cloned cDNAin transfected cells, using the wildtype construct and site-specific mutant constructs. Asparagine 43, of one ofthe two potential N-linked glycosylationsites in lipoprotein lipase, was found to be important for both enzymeactivity and secretion. Mutations involving someoftheserine residues also produced marked changes in enzymeactivity. The possible structural changes associated with these functionally altered mutantlipoprotein lipase molecules are discussed with reference to the crystal structure of human pancreatic lipase, a lipolytic enzyme with considerable sequence homology to lipoprotein lipase.
    • FLOW INJECTION ANALYSIS FOR THE ON-LINE DETECTION OF LIPASE; A TOOL FOR THE AUTOMATIZATION OF LIQUID CHROMATOGRAPHY

      Erdmann, Helmut; Chemnitius, Gabriele C.; Schmid, Rolf D.; GBF- Gesellschaft fiir Biotechnologische Forschung, Abt. fiir Enzymtechnologie, Mascheroder Weg 1, 3300 Braunschweig - FRG (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      The application of a FIA-FPLC unit for the post-column on-line detection of lipase activity is presented. As the developmentof techniques such as Fast Protein Liquid Chromatography (FPLC) and High Performance Liquid Chromatography (HPLC) has greatly reduced the time required for protein purification, fast identification of enzyme-containingfractions is desired. Rapid detection of enzymeactivity can be achieved by coupling a flow injection analysis (FIA) system to the liquid chromatography unit. Usually lipase activity is detected in the presence of emulsified substrates, whose evendistribution in the FIA system causes problems. In orderto solve these problems, the solubilized substrates S,O,O’-tributyryl-1-thiogycerol (TBTG) and 1,2-O-dilauryl-rac-glycero-3- glutaric-resorufinester (BM) were applied to determine the relationship between lipase concentration and FIA response. Lipase and its substrate were injected simultaneously into two carrier streams which were mixed together before passing a thermostated reaction coil. The cleaved productof the lipase substrate was detected photometrically. The BM-substrate turned out to be most suitable for FIA applications. The FPLC-FIA unit using the BM-substrate has successfully been applied for post-column on-line monitoring of lipase activity during different lipase purification steps. FIA response showsa linear correlation to lipase activity up to lipase concentrations of 120 U/ml.
    • INHIBITION OF THE LIPASE FROM PSEUDOMONASSPEC. ATCC 21808 BY DIETHYL p-NITROPHENYL PHOSPHATE. HINTS FOR ONE BURIED ACTIVE SITE FOR LIPOLYTIC AND ESTEROLYTIC ACTIVITY

      Kordel, Marianne; Schmid, Rolf D.; GBF, Gesellschaft für Biotechnologische Forschung mbH, Dept. of Enzyme Technology, Mascheroder Weg 1, D-3300 Braunschweig (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      Lipases have been shown to beserine-hydrolasessince they are inhibited by serine active reagents such as phenylmethylsulfonylfluoride (PMSF), boronic acids and organophosphates [1,2,3]. Furthermore, they are surface active enzymes,i.e. they are activated by binding to interfaces [4] comprising their natural substrates, the micelles of long chain fatty acid triglycerides. It has long been postulated that lipases undergo a conformational changein this activation process. Recently it became obvious from x-raystudies [1,5] that the active site is inaccessible to voluminoussubstrates unless a conformational change occurs sincethe active site is buried undera lid formed by a long peptide loop. The lipase from human pancreas presumably hydrolysessoluble substrateslike p-nitrophenyl acetate (pNPA)at a different site [5]. For the porcine pancreatic lipase it was reported that the C-terminal peptide fragment (336-449) shows the sameactivity towards pNPA as the complete enzyme but no activity towards triacylglycerols [6]. Whereas,in the triglyceride hydrolysis Ser-152 is involved [R. Verger, pers. communication]. Ourinhibition studies suggest that only one active site for both types of substrates exists for the lipase from Pseudomonas spec. ATCC 21808 and thatthis site is buried.
    • EXTRACELLULAR LIPASE OF PSEUDOMONAS AERUGINOSA

      Jaeger, Karl-Erich; Wohlfarth, Susanne; Winkler, Ulrich K.; Ruhr-Universität, Lehrstuhl Biologie der Mikroorganismen, D-4630 Bochum, FRG (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      Lipase of Pseudomonas aeruginosa was excreted in form of high M,- aggregates consisting of protein and lipopolysaccharide. Solubilization and isoelectric focusing in the presence of the zwitterionic detergent CHAPS yielded in an electrophoretically pure lipase protein of M, 29 kDa with an isoelectric point of 5.9. Charge shift electrophoresis showed that lipase was an amphiphilic protein, its activity was dependent on the presence of detergent. Lipase cleaved a variety of different substrates showing no positional specificity. The lipase gene was cloned and sequenced revealing the lipase consensus sequence Gly-His-Ser-His-Gly. Polyclonal antibodies were raised against purified lipase having a titer of 1400 and a detection limit in the picogram range.
    • PANCREATIC LIPASE/COLIPASE BINDING SITE INVESTIGATION

      Chaillan, Catherine; Foglizzo, Edith; Granon, Simone; Lombardo, Dominique; Chapus, Catherine; Centre de Biochimie et de Biologie Moléculaire du CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 9, FRANCE (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      Pancreatic lipase is responsible for fat digestion in the intestine. The enzyme, which belongs to a special class of esterases, realizes an heterogeneous catalysis. In vivo, because of the strong inhibitory effect of bile salt,the lipase action requires the presence of a small pancreatic protein, colipase, the function of which is to anchor lipase to the bile salt coated lipid interface. The function of the lipase/colipase system requires the presence of two topographically distinct binding sites on both proteins, an interfacial binding site and a protein binding site. Up to now, only the colipase interfacial binding site is well documented. In order to locate the lipase/colipase binding site on each partner, a covalent cross-linked complex has been obtained using carbodiimides. Immunological analysis of the complex clearly confirms the presence of lipase and colipase. The complex has a Mr (60 kDa) consistent with a stoichiometry of one mol colipase per mol lipase and retains its catalytic efficiency towards emulsified substrates. Moreover, the use of carbodiimides to cross-link lipase and colipase unambiguously shows the participation of ion-pairing in the interaction between the two proteins.
    • LIPOLYTIC ENZYMES SEPARATION AND PURIFICATION THROUGH FUNCTIONALIZED SYNTHETIC POLYMERS

      Cernia, E.; Magri, A. D.; Ortaggi, G.; Castagnola, M.; Rabino, R.; Bartoli, F.; Universita di Roma "La Sapienza"; Universita Cattolica di Roma; C.T.B - Roma (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      A new class of functionalized synthetic polymers was prepared for the purification of lipases by a single step affinity chromatography. Polyvinyl alcohol polymers were crosslinked with epichlorohydrin and esterified with fatty acids of different length. The resulting resins were characterized by infrared spectroscopy, electron microscopy and titration of the hydrolysed product to evaluate the degree of esterification. The attention was focused on lauryl ester of polyvinyl alcohol as commercial preparation of Candida cylindracea lipase showed the highest enzyme affinity for esters of fatty acids with a linear chain ranging from 8 to 12 carbon atoms. Chromatographic lipase purification trials were performed on a 7 cm x 1.6 cm i.d. column. Good separation conditions were found by utilizing stepwise increase in CHAPS (3-(3-(cholamido-propyl)-dimetil-ammonio)-1-propan sulfonate) concentration in HEPS/EDTA buffer. The lipase obtained by elution with CHAPS 6.0 mmol/L showed a high purity, as established by SDS-PAGE, where an unique band with a molecular weight of 60.000 was identified.
    • LIPASE-CATALYZED HYDROLYSIS OF TRIGLYCERIDES FROM NEW OIL CROPS FOR OLEOCHEMICAL INDUSTRIES

      Derksen, J. T. P.; Boswinkel, G.; van Gelder, W. M. J.; ATO Agrotechnological Research Institute, P.O. Box 17, 6700 AA Wageningen, The Netherlands (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      The use of Rhizopus delemar lipase to specifically and mildly isolate industrially interesting fatty acids from new agricultural oil seed crops was evaluated. R. delemar-mediated hydrolysis of Crambe and Dimorphotheca oils was studied in an emulsion system at room temperature. Crambe oil hydrolysis was also studied using lipase, immobilized in a two-phase hollow-fiber membrane bioreactor. Progress of the hydrolysis was monitored by GLC analysis. Allowing the reaction to proceed in an oil - water emulsion gave a high yield of erucic acid when using Crambe oil, and dimorphecolic acid when using Dimorphothecaoil. R. delemar-mediated hydrolysis of Crambe oil in a membrane bioreactor also yielded high proportions of erucic acid, albeit at a lower apparentrate. It is concluded that lipases with 1,3-positional specificity can be used to produce high concentrations of specialty fatty acids from novel vegetable oils and that immobilization of these lipases in membrane bioreactors allows re-use of the enzyme, thus potentially increasing cost-effectiveness of the reaction.
    • LIPASE CATALYSED RESOLUTION OF BICYCLIC BUILDING BLOCKS FOR LEUKOTRIENE SYNTHESIS: ADVANTAGES OF ORGANIC MEDIA

      Spreitz, J.; Grobbauer, R.; Griengl, H.; Faber, K.; Institute of Organic Chemistry, Graz University of Technology, Stremayrgasse 16, A-8010 Graz, Austria (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      The bicyclic bromohydrins rac-la,b were conveniently resolved with lipases from Pseudomonas (Amano P) and Candida cylindracea (Amano AY-30) using vinyl acetate as acyl donor and solvent. Both enantiomers could be obtained with >96% e.e.
    • INTRINSIC ACTIVITY AND CATALYTIC RESIDUES OF THE LIPASE FROM GEOTRICHUM CANDIDUM

      Spener, F.; Hedrich, H. C.; Menge, Ulrich; Schmid, Rolf D.; Institut für Biochemie, Universität Münster, Wilhelm-Klemm-Str. 2, D-4400 Münster; Abteilung Enzymtechnologie, Gesellschaft für Biotechnologische Forschung, Mascheroder Weg1, D-3300 Braunschweig-Stöckheim (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      The triacylglycerol hydrolase secreted by Geotrichum candidum reportedly prefers substrates having fatty acids with a cis-double bondin A9-position. A simple and rapid two step methodfor the purification of high amountsofthis lipase was developedstarting from the commercially available "GC-4" lipase powder (Amano, Japan). The molecular massof the purified lipase was 61 kDa, the carbohydrate content 8.8 %. The heterogeneity observedin isoelectric focusing was dueto variable glycosylation of the core protein. With the aim to bioengineer new product oils the lipase was immobilized to an anion exchanger and usedascatalystin the acidolytic modification of subcutaneouscalf fat with isostearic acid. Reaction rates and yields were lower in comparisonto catalysis by other immobilized microbiallipases. With the immobilizate of Geotrichum candidumlipaseoleic acid waspreferentially replaced in the triglycerides by isostearic acid, however. This unique substrate specificity of the enzyme thus prevails in transesterification processes as well. Modification studies with reagents specific for amino acid residues presumedto be active in the catalytic center showedthat the Geotrichum candidumlipase wasvery resistentto inhibition, as only a carbodiimide and photooxydation rendered the lipase inactive. With the aim to enhance the accessibility of the active center, reagents were then applied in the presence of 20 % isopropanol and inhibition with the serine specific reagents phenylmethylsulfony!fluoride and benzene boronic acid was achieved. Thedata indicate that a catalytic triad aspartic acid : histidine : serine may beinvolvedin catalysis.
    • CULTIVATION STRATEGIES OF REC LIPASE FROM STAPHYLOCOCCUS CARNOSUS

      Falk, M. P. F.; Sanders, E.; Deckwer, Wolf-Dieter; Erdmann, Helmut; GBF, Gesellschaft fiir Biotechnologische Forschung mbH, Mascheroderweg 1, D-3300 Braunschweig, Federal Republic of Germany (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      Increasing interest in lipases has led to the developement of new applications and production processes. Scince manyyears it has been knownthat certain Staphylococci produce extracellular lipases (Arvidson et al., 1971; Sztajer et al., 1987). Some species are pathogenic, while others have been extensively used as starter cultures for food industry. In this work the formation of a lipase from S. carnosus TM 300 whichis generally recognized as safe was studied. The organism carrying a plasmid pLipPS1 with the lipase gene from S. hyicus was constructed by Götz et al. (1985). Lipase production from bacterial strains depends on environmental factor such as cultivation temperature, composition of nitrogen, carbon and lipid sources, the concentration of inorganic salts and the availability of oxygen. Additionaly, care must be taken to preserve the biological activity of the product. When carrying out cultivations of S. carnosus TM 300::pLipPS1 in shaking flasks without baffles a lipase production of more than 20 mg/l was obtained. In contrast to this result, the cultivation in a lab scale stirred and aerated fermentor yielded muchless lipase. As shown in this paper, this discrepancy originates from differences in cultivation conditions which maylead to lipase inactivation.
    • Lipase, Enzymatically Active in a Monolayer

      Gloger, T. M.; Maksymiw, R.; Erdmann, Helmut; Nitsch, W.; Technical University Munich, Institute of Technical Chemistry, Lichtenbergstr. 4, D - 8046 Garching, FRG; GBF Braunschweig (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      The present work is focussed on the interfacial behaviour and the enzymatic activity of Staphylococcus carnosus lipase monolayersat the water/air and water/tolueneinterface. Stable enzyme layers were established at the water/air interface by quantitative spreading according to Trurnit (1). Thus, a monolayer with a definite number of molecules is obtained, exclusively. Therefore the resulting pressure/area diagramscanbeinvestigated with regard to molecular data. A characteristic feature is the occuranceof a critical pressure 7, ~ 18 mN/m in the pressure/area diagrams. This critical pressure occurs in many protein pressure/area diagrams. In the caseoflipase, Tig is pHindependent and can be demonstrated to correspond to a closely packed monolayer of compact molecules. From the corresponding molecular area A. (= 5000 A2) the molecules can be postulated to be discs lying flat on the surface and the radius and thickness can be calculated to 40 Aand 20 A, respectively. The covering of the monolayer with a toluene-phase changes the intermolecular interactions: The pressure/area curve progresses beyondthe corresponding water/air curve. For pressureshigher than rm, and molecular areas smaller than A, the difference diminishes. The values of m,/A, at water/air and water/toluene were the same. Asfor the water/air interface thecritical pressure is pH-independent. For studying enzymatic activity at the water/air interface a novel apparatus is presented, which combines a filmbalance with a convection reactor. Thus, it is possible to study the enzymatic reaction of a definite monolayer in a defined hydrodynamical environment. The enzymatic monolayerturns out ta be active and its reaction resembles the corresponding homogeneous reaction. Thus support is given for the view,that enzymes are not necessarily denatured on their contact with an interface, but can keep a compact and active configuration.
    • Physicochemical Properties of Mono- and Diacylglycerol Lipase from Penicillium camembertii

      Isobe, K.; Nokihara, Kiyoshi; Amano Pharmaceutical Co. Ltd., 1-2-7 Nishiki, Naka-Ku, Nagoya, Aichi 460, Japan; GBF-Gesellschaft für Biotechnologische Forschung, Mascheroder Weg 1, D-3300 Braunschweig, F.R.Germany (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      In the course of investigations on the enzymatic synthesis of monoglycerides and the partial hydrolysis of glycerides, Yamaguchi and Mase found a newlipase havingstrict specificity to mono- and diacylglycerols but not to triacylglycerols in the culture broth of Penicillium camembertii U-150 (1). The newlipase was purified into four active fractions by a procedure involving ethanol precipitation, ammanium sulfate fractionation, and aminooctyl-Sepharose, hydroxyapatite and concanavalin A-Sepharose (con A Sepharose) column chromatographies. One active fraction, enzyme 1, was not adsorbed on con A-Sepharose but others, enzymes 2- 4, were adsorbed on con A Sepharose and separated into three active fractions by linear gradient elution with Methyl-X-D-glycopyranoside. No significant difference was observed in substrate specificity among enzymes 1-4, but other enzymatic properties, e. g., pH and heatstabilities, and optimum pH and temperature, were clearly different between enzyme 1 and three adsorbed components (three adsorbed components weresimilar to each other)(2). In oder to elusidate multiple forms of this enzyme, the physicochemical properties were compared among four active components.
    • PURIFICATION AND SUBSTRATE SPECIFICITIES OF LIPASES FROM GEOTRICHUM CANDIDUM

      Charton, E.; Davies, C.; Sidebottom, C. M.; Sutton, J. L.; Dunn, P. P. J.; Slabas, A. R.; Macrae, A. R.; Unilever Research, Colworth Laboratory, Sharnbrook, Bedford, MK44 1LQ, UK (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      Two strains of the mould Geotrichum candidum (ATCC 34614 and CMICC 335426) each produce two extracellular lipases. We have purified the four lipases to electrophoretic homogeneity and each is a single species when analysed by isoelectric focusing. The enzymes are glycosylated and have similar molecular weights and isoelectric points. Peptide mapping and Western blotting shows that the lipases are related and this has been confirmed by amino acid analysis. We have examined the substrate specificities of the two lipases using triacylglycerols and fatty acid methyl esters as substrates. One lipase is highly specific for the release of cis-A9-fatty acids from these substrates. In contrast, the other 3 lipases are not specific, releasing both saturated and unsaturated fatty acids.
    • PROPERTIES AND PARTIAL PURIFICATION OF A PSEUDOMONAS CEPACIA LIPASE

      Dünhaupt, A.; Lang, S.; Wagner, Fritz; Institute of Biochemistry and Biotechnology, Technical University, D-3300 Braunschweig, West-Germany (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      A high lipolytic activity (65 umol/ml min.) was observed in the supernatant of Pseudomonas cepacia DSM 50181 after growth on olive oil. The crude lipase was investigated with respect to substrate specifity, pH- and temperature optima. The hydrolysis of short chain triglycerides and of the unsaturated triolein indicated a higher lipolytic activity than in the case of long chain substances (37°C). The p-nitrophenyl- esters of fatty acids showed maximum activity for the palmitate. This was the same maximum which was observed for triglycerides in the range from C12 to C18 at 75°C. An inhibition of lipolytic activity was noticed by adding oleic acid during the hydrolysis of olive oil. Furthermore an inactivation of the lipase occured when the interface liquid/gaseous was increased. The addition of an inert lipophilic substance or of detergents could neutralize this effect. A partial purification of the lipolytic enzyme could be achieved by liquid/liquid extraction and ionexchangechromatography. This enrichment procedures led to a purification factor of 55 with a recovery of 30%. Isoelectric focussing showed a main protein band at pl 7.1.
    • PRODUCTION AND SOME PROPERTIES OF PARTIALLY PURIFIED LIPASE FROM PENICILLIUM SIMPLICISSIMUM

      Sztajer, Helena; Erdmann, Helmut; Isobe, K.; Morelle, Gilles; Schmid, Rolf D.; GBF, Gesellschaft fuer Biotechnologische Forschung mbH, Mascheroder Weg 1, D-3300 Braunschweig, F.R.G.; Amano Pharmaceutical Co., ltd, 2-7, 1-chome, Nishiki, Naka-ko, Nagoya 460, Japan (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) are widely distributed throughout fungi. Two lipolytic fungi commonly used in the manufacture of Camembert and Brie cheeses are Penicillium camembertii and P. caseicolum. Lipolytic activity was also discovered in a P. chrysogenum strain [1]. Lipase from P. cyclopium M1 specific to p-nitrophenyl laurate has been purified and crystallized [2]. Three lipases were discovered in the culture broth of P. crutosum [3], two of them were purified and crystallized [3]. We describe here a lipolytic activity of P. simplicissimum, the purification and some properties of the lipase.
    • THE BEHAVIOUR OF THE CANDIDA RUGOSALIPASEIN THE PRESENCE OF SOLUBLE SUBSTRATES

      Flaschel, Erwin; Renken, Albert; Institut de génie chimique, Ecole Polytechnique Fédérale de Lausanne EPFL-Ecublens, CH-1015 Lausanne, Switzerland; Arbeitsgruppe Fermentationstechnik, Technische Fakultät, Universität Bielefeld P.O.Box 6840, D-4800Bielefeld 1, Germany (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      New data are presented for the reaction behaviour of the C. rugosalipase in the presence of soluble substrates. The expected interpretation in terms of the formation of a dimeric species ofthe enzyme has found a rival model in the adsorption of the lipase on the surface of the reactor made of glass.
    • The Physiology of Lipase Production by Pseudomonas species

      Gilbert, E. J.; Drozd, J. W.; Jones, C. W.; Department of Biochemistry, University of Leicester, Leicester LE1 7RH; Shell UK Limited, Shell-Mex House, Strand, London WC2R ODX (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      1. Lipase production by the Pseudomonasspecies was induced by growth on Tween80. 2. Maximum activity was observed under Tween 80-limited conditions. 3. Production of lipase in a Tween 80-limited continuous culture has been optimised. 4. Lipase has been purified to homogeneity, and someofits physicochemical properties determined.
    • Purification and Kinetic Studies of Lipases Using Reversed Micellar Systems

      Aires-Barros, M. R.; Cabral, J. M. S.; Laboratério de Engenharia Bioquimica, Instituto Superior Técnico, 1000 Lisboa, Portugal (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      Selective separation and purification of two lipases (A and B) from Chromobacterium viscosum were carried out by liquid-liquid extraction using a reversed micellar system (250 mM AOTin isooctane), with selective extraction of lipase B to the micellar phase and lipase A remaining in aqueous solution. The purified lipases were used to catalyze esterification reactions between carboxylic acids and alcohols in reversed micelles. The influence of various parameters in the synthesis of oleyl propionate by lipases A and B, was studied. The maximum activity was obtained at Wo([H20]/[AOT])=6.7.
    • Comparison of Lipase Activities by Different Assays

      Erdmann, Helmut; Vorderwülbecke, T.; Schmid, Rolf D.; Kieslich, Klaus; GBF,Gesellschaft fiir Biotechnologische Forschung mbh, Mascheroder Weg 1, D- 3300 Braunschweig, F.R.G. 1. Dept. of Enzyme Technology; 2. Dept. of Microbial Transformation (GBF Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, 1991)
      Recently several quick assay procedures have been developed (1 to 15), and are saidto detect lipase activity. The hydrolysis of Triglycerols and artificial substrates oftencan not explain differences of whatis a lipase and whatis an esterase. We established a numberoflipase assays for the estimation ofactivities for a large numberof different lipase preparations, as immobilized pure enzymes, nearly homogeneous preparations and samples of industrial grade. We found remarkable differences concerning the lipase activities measured with different assays and report about characteristics and comparability. At last, we want to arise the question "do we look for the enzymes we are interested in ?"