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Enzymatic Synthesis (enzymatic + synthesis)
Selected AbstractsOPTIMIZATION OF ENZYMATIC SYNTHESIS OF ISOMALTO-OLIGOSACCHARIDES PRODUCTIONJOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2009M.C. RABELO ABSTRACT Glucosyltransferases can be applied in the synthesis of prebiotic oligosaccharides. Enzymatic synthesis using acceptors can be used to obtain these carbohydrates. When maltose is the acceptor, oligosaccharides containing one maltose moiety and up to eight glucose units linked by ,-1,6-glycosidic bonds are obtained as the product of dextransucrase acceptor reaction. In this work, the enzymatic synthesis of isomalto-oligosaccharides using dextransucrase from Leuconostoc mesenteroides NRRL B-512F was optimized by response surface methodology. The effect of maltose and sucrose concentrations on the acceptor reaction was evaluated in a batch reactor system. Partially purified enzyme was used to reduce the enzyme purification cost. The results showed that high sucrose concentrations in conjunction with high maltose levels enhanced the isomalto-oligosaccharide synthesis. A productivity of 42.95 mmol/L.h of isomalto-oligosaccharides was obtained at the optimal operating condition (100 mmol/L of sucrose and 200 mmol/L of maltose). PRATICAL APPLICATIONS Oligosaccharides as prebiotic have a large application in food formulations, and their beneficial role in human health have been extensively studied. Although the acceptor mechanism of dextransucrase has already been extensively studied, an industrial process has not been developed yet for enzyme synthesis of isomalto-oligosaccharide. The process studied in this work allows the large-scale preparation of isomalto-oligosaccharide using partially purified enzyme. [source] Integrated Enzymatic Synthesis and Adsorption of Isomaltose in a Multiphase Fluidized Bed ReactorENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2006M. Ergezinger Abstract Dextransucrase catalyzes the formation of dextran, but also of numerous oligosaccharides from sucrose and different acceptors, if appropriate conditions are chosen. A process on a technical scale with immobilized enzyme was established to produce isomaltose, a disaccharide of industrial interest. Isomaltose is also a reactant for dextransucrase and has to be quickly taken out of the reaction solution. This was realized by integrated adsorption of isomaltose on zeolites. In the case of biotransformation the reactor works with a fluidized bed of immobilized enzyme and the in situ separation is realized with a suspension flow of adsorbent. This process was investigated experimentally and theoretically. With a design model consisting of hydrodynamics, kinetics of enzymatic synthesis, and thermodynamics of adsorption, a comparison was made between experimental and calculated data. [source] Preparative Enzymatic Synthesis of the Acylglucuronide of Mycophenolic AcidADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6-7 2003Matthias Kittelmann Abstract The acylglucuronide (3) of mycophenolic acid (1) was enzymatically synthesised on a preparative scale (450,mg substrate) under optimised reaction conditions with 51% conversion. By screening 9 liver homogenates from 8 vertebrate species, it was shown that only with liver homogenate from horse as the catalyst were the acyl- (3) and the O -glucuronide (2) were formed in a ca. 1,:,1 ratio. With homogenates from other sources, the O -glucuronide (2) was produced in high excess. By optimising the concentration of the co-substrate UDP-glucuronic acid and the reaction temperature, the conversion to the acylglucuronide (3) was increased from initially 34 to 55% and the ratio of acyl- (3) to O -glucuronide (2) from 1.5,:,1 to 3.9,:,1. The reaction was also performed continuously in an enzyme membrane reactor, however, with lower conversion yield and therefore, higher specific UDP-glucuronic acid consumption. [source] Enzymatic Synthesis of Chitin- and Chitosan- graft -Aliphatic PolyestersMACROMOLECULAR RAPID COMMUNICATIONS, Issue 20 2004Masayori Fujioka Abstract Summary: The title polymers, in which both the stem and the graft are biodegradable, have been synthesized for the first time in a one-pot, lipase-catalyzed, graft-polymerization reaction (in bulk, at 70,°C) of , -butyrolactone (, -BL) and , -caprolactone (, -CL) onto chitin and chitosan. The reactivity order of the lactones was found to be , -CL,>,, -BL,,,, -BL (no reaction). All the graft polymers prepared are insoluble in common organic solvents. Synthesis of chitin- or chitosan- graft -aliphatic polyesters. [source] Enzymatic Synthesis of 3,-Hydroxyacetaminophen Catalyzed by TyrosinaseBIOTECHNOLOGY PROGRESS, Issue 6 2003Edelmira Valero 3,-Hydroxyacetaminophen, a catechol metabolite of N -acetyl- p -aminophenol (acetaminophen) and N -acetyl- m -aminophenol (a structural analogue of acetaminophen and considered as a possible alternative because it is not hepatotoxic), is enzymatically synthesized for the first time using mushroom tyrosinase. Although reported to be weakly hepatotoxic in vivo, this catechol derivative of acetaminophen is not commercially available. This compound was obtained from its monophenolic precursor, acetaminophen, using the enzyme tyrosinase in the presence of an excess of ascorbic acid, thus reducing back the o -quinone product of catalytic activity to the catechol acetaminophen derivative. A mathematical model of the system is proposed, which is also applicable to the tyrosinase-mediated synthesis of any o -diphenolic compound from its corresponding monophenol. This synthesis procedure is continuous, easy to perform and control, and adaptable to a bioreactor with the immobilized enzyme for industrial purposes in a nonpolluting way. [source] Enzymatic Synthesis of Enantiopure ,- and ,-Amino Acids by Phenylalanine Aminomutase-Catalysed Amination of Cinnamic Acid DerivativesCHEMBIOCHEM, Issue 2 2009Bian Wu Abstract The phenylalanine aminomutase (PAM) from Taxus chinensis catalyses the conversion of ,-phenylalanine to ,-phenylalanine, an important step in the biosynthesis of the N -benzoyl phenylisoserinoyl side-chain of the anticancer drug taxol. Mechanistic studies on PAM have suggested that (E)-cinnamic acid is an intermediate in the mutase reaction and that it can be released from the enzyme's active site. Here we describe a novel synthetic strategy that is based on the finding that ring-substituted (E)-cinnamic acids can serve as a substrate in PAM-catalysed ammonia addition reactions for the biocatalytic production of several important ,-amino acids. The enzyme has a broad substrate range and a high enantioselectivity with cinnamic acid derivatives; this allows the synthesis of several non-natural aromatic ,- and ,-amino acids in excellent enantiomeric excess (ee >99,%). The internal 5-methylene-3,5-dihydroimidazol-4-one (MIO) cofactor is essential for the PAM-catalysed amination reactions. The regioselectivity of amination reactions was influenced by the nature of the ring substituent. [source] Non-Heme Hydroxylase Engineering For Simple Enzymatic Synthesis of L - threo -Hydroxyaspartic AcidCHEMBIOCHEM, Issue 3 2008Matthias Strieker The direct hydroxylation of aliphatic carbon atoms is a challenging task in organic chemistry. Nature's unique ability to solve this problem by using non-heme iron hydroxylases was applied to the stereospecific synthesis of the medically important compound L - threo -hydroxyaspartic acid. We switched the substrate specificity of a hydroxylase (AsnO) from L -asparagine to L -aspartic acid by a simple side chain swap in the substrate binding pocket. [source] ChemInform Abstract: Enzymatic Synthesis of Monocyclic ,-Lactams.CHEMINFORM, Issue 21 2002Mark C. Sleeman 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] ChemInform Abstract: Enzymatic Synthesis of Pyruvic Acid from Acetaldehyde and Carbon Dioxide.CHEMINFORM, Issue 2 2002Masaya Miyazaki 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] OPTIMIZATION OF ENZYMATIC SYNTHESIS OF ISOMALTO-OLIGOSACCHARIDES PRODUCTIONJOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2009M.C. RABELO ABSTRACT Glucosyltransferases can be applied in the synthesis of prebiotic oligosaccharides. Enzymatic synthesis using acceptors can be used to obtain these carbohydrates. When maltose is the acceptor, oligosaccharides containing one maltose moiety and up to eight glucose units linked by ,-1,6-glycosidic bonds are obtained as the product of dextransucrase acceptor reaction. In this work, the enzymatic synthesis of isomalto-oligosaccharides using dextransucrase from Leuconostoc mesenteroides NRRL B-512F was optimized by response surface methodology. The effect of maltose and sucrose concentrations on the acceptor reaction was evaluated in a batch reactor system. Partially purified enzyme was used to reduce the enzyme purification cost. The results showed that high sucrose concentrations in conjunction with high maltose levels enhanced the isomalto-oligosaccharide synthesis. A productivity of 42.95 mmol/L.h of isomalto-oligosaccharides was obtained at the optimal operating condition (100 mmol/L of sucrose and 200 mmol/L of maltose). PRATICAL APPLICATIONS Oligosaccharides as prebiotic have a large application in food formulations, and their beneficial role in human health have been extensively studied. Although the acceptor mechanism of dextransucrase has already been extensively studied, an industrial process has not been developed yet for enzyme synthesis of isomalto-oligosaccharide. The process studied in this work allows the large-scale preparation of isomalto-oligosaccharide using partially purified enzyme. [source] Enzymatic synthesis of l-tryptophan and 5prime-hydroxy-l-tryptophan labeled with deuterium and tritium at the alpha-carbon positionJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 8 2003E. Boroda Abstract The enzymatic synthesis of l-tryptophan and its derivative 5,-hydroxy-l-tryptophan labeled with deuterium and tritium at the ,-carbon position is reported. The mixture containing S -methyl-l-cysteine, indole or 5-hydroxyindole dissolved in deuteriated or tritiated water has been converted to [2- 2H]-l-tryptophan, [2- 3H]-l-tryptophan, 5,-hydroxy-[2- 2H]-l-tryptophan, and 5,-hydroxy-[2- 3H]-l-tryptophan, respectively, in a one-pot reaction using the enzyme tryptophanase. The same reaction carried out in heavy water with THO added yielded either doubly labeled [2- 2H/3H]-l-tryptophan or 5,-hydroxy-[2- 2H/3H]-l-tryptophan. Copyright © 2003 John Wiley & Sons, Ltd. [source] Enzymatic synthesis and biodistribution in mice of , -O-D-galactopyranosyl-(1,4,)-2,-[18F]fluoro-2,-deoxy-D-glucopyranose (2,-[18F]fluorodeoxylactose]JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 6 2001G. Bormans Abstract We have synthesized , -O- D -galactopyranosyl-(1,4,)-2,-[18F]fluoro-2,-deoxy- D -glucopyranose (2,-[18F]fluorodeoxylactose, 18FDL) using an enzymatic method starting from 18FDG in order to evaluate this compound with regard to its usefulness for in vivo visualization of the expression of the LacZ gene. Incubation of 18FDL with , -galactosidase results in the formation of 18FDG. Biodistribution studies in normal mice showed that 18FDL is cleared by urinary excretion and is not retained in any tissue. Biodistribution in Rosa-26 mice is identical to the biodistribution in normal mice, suggesting that 18FDL is not able to cross the cell membrane. Copyright © 2001 John Wiley & Sons, Ltd. [source] Enzymatic synthesis of specialty surfactantsBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2009Article first published online: 19 OCT 200 No abstract is available for this article. [source] Integrated Enzymatic Synthesis and Adsorption of Isomaltose in a Multiphase Fluidized Bed ReactorENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2006M. Ergezinger Abstract Dextransucrase catalyzes the formation of dextran, but also of numerous oligosaccharides from sucrose and different acceptors, if appropriate conditions are chosen. A process on a technical scale with immobilized enzyme was established to produce isomaltose, a disaccharide of industrial interest. Isomaltose is also a reactant for dextransucrase and has to be quickly taken out of the reaction solution. This was realized by integrated adsorption of isomaltose on zeolites. In the case of biotransformation the reactor works with a fluidized bed of immobilized enzyme and the in situ separation is realized with a suspension flow of adsorbent. This process was investigated experimentally and theoretically. With a design model consisting of hydrodynamics, kinetics of enzymatic synthesis, and thermodynamics of adsorption, a comparison was made between experimental and calculated data. [source] Diastereoselective Synthesis of -Hydroxy Sulfoxides: Enzymatic and Biomimetic ApproachesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2007Stefano Colonna Abstract Stereoselectivities of up to 98,% have been found in the enzymatic synthesis of ,-hydroxy sulfoxides catalyzed by cyclohexanone monooxygenase (CHMO). The diastereoselectivity of the "one-pot" preparation of the title compounds in the presence of bovine serum albumin has also been investigated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Selenium affects biosilica formation in the demosponge Suberites domunculaFEBS JOURNAL, Issue 15 2005Effect on gene expression, spicule formation Selenium is a trace element found in freshwater and the marine environment. We show that it plays a major role in spicule formation in the demosponge Suberites domuncula. If added to primmorphs, an in vitro sponge cell culture system, it stimulates the formation of siliceous spicules. Using differential display of transcripts, we demonstrate that, after a 72-h exposure of primmorphs to selenium, two genes are up-regulated; one codes for selenoprotein M and the other for a novel spicule-associated protein. The deduced protein sequence of selenoprotein M (14 kDa) shows characteristic features of metazoan selenoproteins. The spicule-associated protein (26 kDa) comprises six characteristic repeats of 20 amino acids, composed of 10 distinct hydrophobic regions (, 9 amino acids in length). Recombinant proteins were prepared, and antibodies were raised against these two proteins. Both were found to stain the central axial filament, which comprises the silicatein, as well as the surface of the spicules. In the presence of selenium, only the genes for selenoprotein M and spicule-associated protein are up-regulated, whereas the expression of the silicatein gene remains unchanged. Finally we show that, in the presence of selenium, larger silica aggregates are formed. We conclude that selenium has a stimulatory effect on the formation of siliceous spicules in sponges, and it may be involved in the enzymatic synthesis of biosilica components. [source] Screening Xanthene Dyes for Visible Light-Driven Nicotinamide Adenine Dinucleotide Regeneration and Photoenzymatic SynthesisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2009Sahng Ha Lee Abstract Regeneration of the nicotinamide cofactor is a critical issue in biocatalysis. Herein we have screened xanthene dyes for a highly efficient, visible light-driven photochemical regeneration of cofactors and enzymatic synthesis. Superior catalytic performance was observed with several xanthene dyes such as phloxine B, erythrosine B, eosin Y, and rose bengal. We found that the photo- and electrochemical properties of the xanthene dyes were affected by the halogen atom substitution, which is a key factor in the efficient light-induced electron transfer from the donor molecule to the catalytic mediator. [source] One-Pot Multienzymatic Synthesis of 12-Ketoursodeoxycholic Acid: Subtle Cofactor Specificities Rule the Reaction Equilibria of Five Biocatalysts Working in a RowADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Daniela Monti Abstract The hydroxysteroid dehydrogenases (HSDHs)-catalyzed one-pot enzymatic synthesis of 12-ketoursodeoxycholic acid (3,,7,-dihydroxy-12-oxo-5,-cholanoic acid), a key intermediate for the synthesis of ursodeoxycholic acid, from cholic acid has been investigated. This goal has been achieved by alternating oxidative and reductive steps in a one-pot system employing HSDHs with different cofactor specificity, namely NADH-dependent HSDHs in the oxidative step and an NADPH-dependent 7,-HSDH in the reductive one. Coupled in situ regeneration systems have been exploited not only to allow the use of catalytic amounts of the cofactors, but also to provide the necessary driving force to opposite reactions (i.e., oxidation and reduction) acting on different sites of the substrate molecule. Biocatalysts suitable for the set-up of this process have been selected and their kinetic behaviour in respect of the reactions of interest has been evaluated. Finally, the process has been studied employing the enzymes both in free and compartmentalized form. [source] Influence of Substrate Structure on PGA-Catalyzed Acylations.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2005Evaluation of Different Approaches for the Enzymatic Synthesis of Cefonicid Abstract The influence of the substrate structure on the catalytic properties of penicillin G acylase (PGA) from Escherichia coli in kinetically controlled acylations has been studied. In particular, the affinity of different ,-lactam nuclei towards the active site has been evaluated considering the ratio between the rate of synthesis (vs) and the rate of hydrolysis of the acylating ester (vh1). 7-Aminocephalosporanic acid (7-ACA) and 7-amino-3-(1-sulfomethyl-1,2,3,4-tetrazol-5-yl)thiomethyl-3-cephem-4-carboxylic acid (7-SACA) showed a good affinity for the active centre of PGA. The enzymatic acylation of these nuclei with R -methyl mandelate has been studied in order to evaluate different approaches for the enzymatic synthesis of cefonicid. The best results have been obtained in the acylation of 7-SACA. Cefonicid (8) was recovered from the reaction mixture as the disodium salt in 65% yield and about 95% of purity. Furthermore, through acylation of 7-ACA, a "one-pot" chemo-enzymatic synthesis was carried out starting from cephalosporin C using three enzymes in sequence: D -amino acid oxidase (DAO), glutaryl acylase (GA) and PGA. Cefonicid disodium salt was obtained in three steps, avoiding any intermediate purification, in 35% overall yield and about 94% purity. This approach presents several advantages compared with the classical chemical processes. [source] OPTIMIZATION OF ENZYMATIC SYNTHESIS OF ISOMALTO-OLIGOSACCHARIDES PRODUCTIONJOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2009M.C. RABELO ABSTRACT Glucosyltransferases can be applied in the synthesis of prebiotic oligosaccharides. Enzymatic synthesis using acceptors can be used to obtain these carbohydrates. When maltose is the acceptor, oligosaccharides containing one maltose moiety and up to eight glucose units linked by ,-1,6-glycosidic bonds are obtained as the product of dextransucrase acceptor reaction. In this work, the enzymatic synthesis of isomalto-oligosaccharides using dextransucrase from Leuconostoc mesenteroides NRRL B-512F was optimized by response surface methodology. The effect of maltose and sucrose concentrations on the acceptor reaction was evaluated in a batch reactor system. Partially purified enzyme was used to reduce the enzyme purification cost. The results showed that high sucrose concentrations in conjunction with high maltose levels enhanced the isomalto-oligosaccharide synthesis. A productivity of 42.95 mmol/L.h of isomalto-oligosaccharides was obtained at the optimal operating condition (100 mmol/L of sucrose and 200 mmol/L of maltose). PRATICAL APPLICATIONS Oligosaccharides as prebiotic have a large application in food formulations, and their beneficial role in human health have been extensively studied. Although the acceptor mechanism of dextransucrase has already been extensively studied, an industrial process has not been developed yet for enzyme synthesis of isomalto-oligosaccharide. The process studied in this work allows the large-scale preparation of isomalto-oligosaccharide using partially purified enzyme. [source] Solid,liquid equilibrium of substrates and products of the enzymatic synthesis of ampicillinAICHE JOURNAL, Issue 6 2010Mônica Santana Abstract The solid,liquid equilibrium of precursors and products of the enzymatic synthesis of ampicillin (AMP) [6-aminopencillanic acid (6-APA) and D(,)phenylglycine (PG)] was investigated at different temperatures (283,298 K) and pHs (5.5,7.5). Solubility data were obtained using an analytical methodology. Equilibrium dissociation constants were experimentally measured at several temperatures for AMP, 6-APA, PG, and D(,)phenylglycine methyl ester. A model based on the simplified perturbed hard sphere theory proposed by Khoshkbarchi and Vera (Ind Eng Chem Res. 1996;35:4319-4327) was fitted against solubility data. The model could describe the water solubility behavior for AMP and PG as function of pH and temperature, but a bias was observed when fitting the model to the solubility of 6-APA. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Stereoselective synthesis of L-[15N] amino acids with glucose dehydrogenase and galactose mutarotase as NADH regenerating systemJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 4 2008Maria Chiriac Abstract We have developed an efficient stereospecific enzymatic synthesis of L-[15N]-valine, L-[15N]-leucine, L-[15N]-norvaline, L-[15N]-norleucine and L-[15N]-isoleucine from the corresponding ,-keto acids by coupling the reactions catalysed by leucine dehydrogenase and glucose dehydrogenase/galactose mutarotase. Giving high yields of L-amino acids, the procedure is economical and easy to perform and to monitor at a synthetically useful scale (1,10,g). Copyright © 2008 John Wiley & Sons, Ltd. [source] Synthesis of [13C]-isotopomers of indole and tryptophan for use in the analysis of indole-3-acetic acid biosynthesisJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 10 2004Neboj, a Ili Abstract The direct conversion of indole to indole-3-acetic acid without tryptophan as an intermediate has previously been shown to occur in vivo, as well as in vitro, with seedlings of plants. In order to facilitate the purification of the enzymes that carry out the enzymatic synthesis of indole-3-acetic acid from labeled indole, it was necessary to develop an assay that had both high sensitivity and analytical precision. To obtain the required analytical resolution and to allow definitive product identification, [13C6]indole was synthesized for use in GC-MS assays of the enzymatic conversion. Plants have been shown to be able to synthesize indole-3-acetic acid either directly from indole as well as by degradation of tryptophan. Thus, in order to allow the biochemical discrimination between these processes, the synthesized [13C6]indole was used as a starting material for a novel enzymatic synthesis of [13C]isotopomers of L -tryptophan labeled at specific positions. Together, these isotope labeled indolic compounds offer powerful new approaches to understanding and differentiating routes of indole-3-acetic acid biosynthesis in vitro and in vivo. Copyright © 2004 John Wiley & Sons, Ltd. [source] Redirecting the inactivation pathway of penicillin amidase and increasing amoxicillin production via a thermophilic molecular chaperoneBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2009Lisa M. Bergeron Abstract We have previously shown that a single-subunit thermosome from Methanocaldococcus jannaschii (rTHS) can stabilize enzymes in semi-aqueous media (Bergeron et al., 2008b). In the present study, rTHS was used to stabilize penicillin amidase (PGA) in methanol,water mixtures. Including methanol in the reaction medium for amoxicillin synthesis can suppress unwanted hydrolysis reactions but inactivate PGA. Inactivation and reactivation pathways proposed for PGA illustrate the predictability of enzyme stabilization by rTHS in co-solvents. Calcium was necessary for reversible dissociation of the two PGA subunits in methanol,water and the presence of calcium resulted in an enhancement of chaperone-assisted stabilization. rTHS also acted as a stabilizer in the enzymatic synthesis of the ,-lactam antibiotic amoxicillin. rTHS stabilized PGA, increasing its half-life in 35% methanol by fivefold at 37°C. Stabilization by rTHS was enhanced but did not require the presence of ATP. Including rTHS in fed-batch reactions performed in methanol,water resulted in nearly 4 times more amoxicillin than when the reaction was run without rTHS, and over threefold higher selectivity towards amoxicillin synthesis compared to aqueous conditions without rTHS. The thermosome and other thermophilic chaperones may thus be generally useful for stabilizing enzymes in their soluble form and expanding the range of conditions suitable for biocatalysis. Biotechnol. Bioeng. 2009;102: 417,424. © 2008 Wiley Periodicals, Inc. [source] Production of ,-Galactosyl Epitopes via Combined Use of Two Recombinant Whole Cells Harboring UDP-Galactose 4-Epimerase and ,-1,3-GalactosyltransferaseBIOTECHNOLOGY PROGRESS, Issue 4 2000Xi Chen ,-Galactosyl epitopes (or ,-Gal, oligosaccharides with a terminal Gal,1,3Gal sequence) are a class of biologically important oligosaccharides in great demand in bulk quantities for basic and clinical studies on preventing hyperacute rejection in pig-to-primate organ xenotransplantaion. A truncated bovine ,-1,3-galactosyltransferase, the key enzyme responsible for the biosynthesis of the terminal structure of ,-Gal, was cloned and overexpressed previously. The acceptor specificity was further studied in the present paper, and lactose and galactose derivatives were found to be good acceptors. To develop a more proficient reaction process, we report herein an example of an efficient enzymatic synthesis of ,-Gal oligosaccharides catalyzed by the combination of two recombinant Escherichia coli whole cells harboring the genes of a UDP-galactose 4-epimerase and the ,-1,3-galactosyltransferase, respectively. Using lactosyl azide (LacN3) as the acceptor for the glycosyltransferase, the combined use of the two recombinant cells efficiently produced ,-Gal epitope Gal,1,3LacN3 in 60,68% yield. [source] | |||||||||||||