References of "Zervosen, Astrid"
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See detailProcess for the synthesis of nucleotide-6-deoxy-D-xylo-4-hexulosen
Marquardt, Ruediger; Hoersch, Brigitte; Seiffert-Stoeriko, Andreas et al

Patent (1999)

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See detailDiagnosis of bovine brucellosis by skin test: conditions for the test and evaluation of its performance.
Saegerman, Claude ULg; Vo, T. K.; De Waele, L. et al

in Veterinary Record : Journal of the British Veterinary Association (1999), 145(8), 214-8

Brucellergene OCB (Rhone-Merieux) was used as an allergen to define the intrinsic parameters of a skin test and to compare its properties with serology for the diagnosis of bovine brucellosis. The skin ... [more ▼]

Brucellergene OCB (Rhone-Merieux) was used as an allergen to define the intrinsic parameters of a skin test and to compare its properties with serology for the diagnosis of bovine brucellosis. The skin test was also evaluated for its capacity to solve problems associated with false positive reactions in serological tests. The optimal reading delay for the skin test was 72 hours. The brucellosis allergic reaction was two to three times less intense than the tuberculosis allergic reaction. An increase of 1.1 mm or more in the skin thickness was therefore considered to be an adequate cut-off. The specificity calculated for 1192 brucellosis-free animals (including animals from brucellosis-free herds in which false positive serological reactions had been reported) was 99-83 per cent (95 per cent confidence interval [CI] 99-40 to 99-98 per cent). The sensitivity determined from 27 experimentally infected heifers ranged from 93 per cent (95 per cent CI 76 to 100 per cent) to 78 per cent (95 per cent CI 58 to 91 per cent) when measured respectively one and six months after the infection. Allergic reactions could be detected in vaccinated animals up to four-and-a-half years after the vaccination. On the other hand, no sensitisation was recorded in naive animals after up to eight monthly injections of the allergen. The skin test gave valuable information, in combination with the serological tests, in both acute and chronic brucellosis. The skin test discriminated brucellosis clearly from false positive serological reactions due to infections with Yersinia enterocolitica O9. [less ▲]

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See detailUDP-N-Acetyl-alpha-D-glucosamine as acceptor substrate of beta-1,4-galactosyltransferase. Enzymatic synthesis of UDP-N-acetyllactosamine.
Elling, Lothar; Zervosen, Astrid ULg; Gallego, Ricardo Gallego et al

in Glycoconjugate Journal (1999), 16(7), 327-36

The capacity of UDP-N-acetyl-alpha-D-glucosamine (UDP-GlcNAc) as an in vitro acceptor substrate for beta-1,4-galactosyltransferase (beta4GalT1, EC 2.4.1.38) from human and bovine milk and for recombinant ... [more ▼]

The capacity of UDP-N-acetyl-alpha-D-glucosamine (UDP-GlcNAc) as an in vitro acceptor substrate for beta-1,4-galactosyltransferase (beta4GalT1, EC 2.4.1.38) from human and bovine milk and for recombinant human beta4GalT1, expressed in Saccharomyces cerevisiae, was evaluated. It turned out that each of the enzymes is capable to transfer Gal from UDP-alpha-D-galactose (UDP-Gal) to UDP-GlcNAc, affording Gal(beta1-4)GlcNAc(alpha1-UDP (UDP-LacNAc). Using beta4GalT1 from human milk, a preparative enzymatic synthesis of UDP-LacNAc was carried out, and the product was characterized by fast-atom bombardment mass spectrometry and 1H and 13C NMR spectroscopy. Studies with all three beta4GalTs in the presence of alpha-lactalbumin showed that the UDP-LacNAc synthesis is inhibited and that UDP-alpha-D-glucose is not an acceptor substrate. This is the first reported synthesis of a nucleotide-activated disaccharide, employing a Leloir glycosyltransferase with a nucleotide-activated monosaccharide as acceptor substrate. Interestingly, in these studies beta4GalT1 accepts an alpha-glycosidated GlcNAc derivative. The results imply that beta4GalT1 may be responsible for the biosynthesis of UDP-LacNAc, previously isolated from human milk. [less ▲]

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See detailApplication of sucrose synthase in the synthesis of nucleotide sugars and saccharides
Zervosen, Astrid ULg; Elling, Lothar

in Bucke, Christopher (Ed.) Carbohydrate Biotechnology Protocols (1999)

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See detailApplication of recombinant sucrose synthase large scale synthesis of ADP-glucose
Zervosen, Astrid ULg; Romer, Ulrike; Elling, Lothar

in Journal of Molecular Catalysis B : Enzymatic (1998), 5(1-4), 25-28

Abstract The synthesis of ADP-glucose with recombinant sucrose synthase from potato was combined with the synthesis of ADP from AMP and ATP catalysed by myokinase from rabbit muscle. By using the ... [more ▼]

Abstract The synthesis of ADP-glucose with recombinant sucrose synthase from potato was combined with the synthesis of ADP from AMP and ATP catalysed by myokinase from rabbit muscle. By using the repetitive-batch-technique we were able to reach enzyme productivities (mg ADP-glucose/U enzyme) of 28 mg/U sucrose synthase and 140 mg/U myokinase yielding 2.8 g ADP-glucose (55% yield). After product isolation, 2.2 g ADP-glucose was obtained corresponding to 44% overall yield. [less ▲]

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See detailLarge scale enzymatic synthesis of ADP-glucose
Zervosen, Astrid ULg; Elling, Lothar

Poster (1997, September 22)

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See detailOne-pot enzymatic synthesis of the Gal alpha 1-->3Gal beta 1-->4GlcNAc sequence with in situ UDP-Gal regeneration.
Hokke, Cornelis H; Zervosen, Astrid ULg; Elling, Lothar et al

in Glycoconjugate Journal (1996), 13(4), 687-92

The trisaccharide Gal alpha 1-->3Gal beta 1-->4GlcNAc beta 1-->O-(CH2)8COOCH3 was enzymatically synthesized, with in situ UDP-Gal regeneration. By combination in one pot of only four enzymes, namely ... [more ▼]

The trisaccharide Gal alpha 1-->3Gal beta 1-->4GlcNAc beta 1-->O-(CH2)8COOCH3 was enzymatically synthesized, with in situ UDP-Gal regeneration. By combination in one pot of only four enzymes, namely, sucrose synthase, UDP-Glc 4'-epimerase, UDP-Gal:GlcNAc beta 4-galactosyltransferase and UDP-Gal:Gal beta 1-->4GlcNAc alpha 3-galactosyltransferase, Gal alpha 1-->3Gal beta 1-->4GlcNAc beta 1-->O-(CH2)8COOCH3 was formed in a 2.2 mumol ml-1 yield starting from the acceptor GlcNAc beta 1-->O-(CH2)8COOCH3. This is an efficient and convenient method for the synthesis of the Gal alpha 1-->3Gal beta 1-->4GlcNAc epitope which pays an important role in various biological and immunological processes. [less ▲]

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See detailCombined enzymatic synthesis of nucleotide (deoxy) sugars from sucrose and nucleoside monophosphates
Zervosen, Astrid ULg; Stein, Andreas; Adrian, Holger et al

in Tetrahedron (1996), 52(7), 2395-2404

Abstract: The synthesis of NDP-glucose 3a-d (N= A, C, U, dU) with sucrose synthase B was combined with the enzymatic synthesis of nucleoside diphosphates 2a-d from their corresponding nucleoside ... [more ▼]

Abstract: The synthesis of NDP-glucose 3a-d (N= A, C, U, dU) with sucrose synthase B was combined with the enzymatic synthesis of nucleoside diphosphates 2a-d from their corresponding nucleoside monophosphates la-d by different kinases A. Further combination with recombinant dTDP-glucose 4,6-dehydratase D enabled us to synthesize dUDP-6-deoxy-alpha-D-xylo-4-hexulose 5 from ld on a preparative scale. By using the repetitive batch technique the enzymatic syntheses of nucleotide (deoxy) sugars 3a-d, 5 could be realized on a 0.1 - 0.5 g scale. [less ▲]

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See detailA novel three-enzyme reaction cycle for the synthesis of N-acetyllactosamine with in situ regeneration of uridine 5'-diphosphate glucose and uridine 5'-diphosphate galactose
Zervosen, Astrid ULg; Elling, Lothar

in Journal of the American Chemical Society (1996), 118(8), 1836-1840

A new three-enzyme reaction cycle consisting of sucrose synthase, UDP glucose 4‘-epimerase, and human β-1,4-galactosyltransferase was established for the synthesis of N-acetyllactosamine (LacNAc) with in ... [more ▼]

A new three-enzyme reaction cycle consisting of sucrose synthase, UDP glucose 4‘-epimerase, and human β-1,4-galactosyltransferase was established for the synthesis of N-acetyllactosamine (LacNAc) with in situ regeneration of UDP galactose. We found that UDP glucose 4‘-epimerase is reductively inactivated in the presence of UMP and acceptor substrates of β-1,4-galactosyltransferase. Reactivation of UDP glucose 4‘-epimerase by the transition state analogues dUDP or dTDP 6-deoxy-d-xylo-4-hexulose in combination with the repetitive batch technique enabled us to use the native enzymes for 11 days in this cycle. With 10 U of sucrose synthase, 5 U of UDP glucose 4‘-epimerase, and 1.25 U of β-1,4-galactosyltransferase, 594 mg of LacNAc could be synthesized. N-Acetyllactosamine was also subsequently converted to Neu5Acα2,6Galβl,4GlcNAc with α-2,6-sialyltransferase and CMP-Neu5Ac. [less ▲]

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See detailPreparative enzymatic synthesis and in situ regeneration of nucleotide sugars with sucrose synthase
Zervosen, Astrid ULg; Stein, Andreas; Elling, Lothar

Conference (1995, July)

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See detailPraeparative enzymatische Synthese von Nucleotidzuckern mit Saccharose Synthase aus Reis
Zervosen, Astrid ULg; Elling, Lothar

Poster (1995, May 30)

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See detailApplication of sucrose synthase from rice grains for the synthesis of carbohydrates.
Elling, Lothar; Grothus, Marita; Zervosen, Astrid ULg et al

in Annals of the New York Academy of Sciences (1995), 750

The enzymatic synthesis of oligosaccharides offers an efficient way to obtain regiospecific and stereo-selective natural and nonnatural target molecules. However, the very expensive activated sugars are ... [more ▼]

The enzymatic synthesis of oligosaccharides offers an efficient way to obtain regiospecific and stereo-selective natural and nonnatural target molecules. However, the very expensive activated sugars are required as substrates for glycosyltransferases. Activated sugars are usually synthesized by pyrophosphorylases from nucleoside triphosphates and sugar-l-phosphates.'.* For cyclic in situ regeneration, at least three enzymes are needed, which makes the synthesis of, for example, N-acetyllactosamine very complex by established procedure. We report here on the enzymatic synthesis of saccharides and activated sugars by the plant glycosyltransferase sucrose synthase (EC 2.4.1.13)! The glycosyltransferase has the unique feature of catalyzing in vitro the synthesis and cleavage of sucrose (SCHEME1 ). The main advantage of sucrose synthase over pyrophosphorylases is the utilization of nucleoside diphosphates (NDP) instead of nucleoside triphosphates to generate activated sugars. [less ▲]

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See detailISOLATION OF SUCROSE SYNTHASE FROM RICE (ORYZA-SATIVA) GRAINS IN PILOT-SCALE FOR APPLICATION IN CARBOHYDRATE SYNTHESIS
ELLING, Lothar; GULDENBERG, Birgit; GROTHUS, Marita et al

in Biotechnology & Applied Biochemistry (1995), 21(Part 1), 29-37

The application of sucrose synthase as a valuable biocatalyst for the synthesis of activated sugars and saccharides requires large amounts of enzyme. The purification of sucrose synthase starting from the ... [more ▼]

The application of sucrose synthase as a valuable biocatalyst for the synthesis of activated sugars and saccharides requires large amounts of enzyme. The purification of sucrose synthase starting from the 9 kg scale of rice (Oryza sativa) grains was achieved in five steps with 11.3% yield and 192-fold purification. The final sucrose synthase preparation was free of nucleotide di- and monophosphatases, but did contain 0.05% of both invertase and UDP-glucose-hydrolysing activity. It can be efficiently utilized for the synthesis of activated sugars. Its application for the synthesis of saccharides is possible taking into account that 15% UDP-glucose is hydrolysed within 15 h incubation time [less ▲]

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See detailCONTINUOUS ENZYMATIC-SYNTHESIS OF 2'-DEOXYTHYMIDINE-5'(ALPHA-D-GLUCOPYRANOSYL)DIPHOSPHATE
Zervosen, Astrid ULg; ELLING, Lothar; KULA, Maria-Regina

in Angewandte Chemie (International ed. in English) (1994), 33(5), 571-572

The preparation of primary nucleotide sugars like dTDP-glucose with sucrose synthase, a glycosyl transferase in plants, provides an alternative in enzymatic synthesis to the use of highly specific ... [more ▼]

The preparation of primary nucleotide sugars like dTDP-glucose with sucrose synthase, a glycosyl transferase in plants, provides an alternative in enzymatic synthesis to the use of highly specific pyrophosphorylases. In an enzyme membrane reactor a continuous synthesis can be performed on preparative scale. [less ▲]

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