PubMed Health⌕ Search

Biomedical subjects

W Praznik

Publications and source records attributed to W Praznik.

9 recordsLinked to original sources
PubMed2002

Soluble dietary fibres in Jerusalem artichoke powders: composition and application in bread.

Powders of tubers from Jerusalem artichoke (Helianthus tuberosus, L.), cultivar Gigant, of different harvesting times (autumn and spring) were applied in bakery products, particularly in wheat/rye bread. The quality of this bread was compared to bread with cereal flours substituted with commercial products as Raftilin ST and Raftilose P95. Compared to standard and substituted bread, Jerusalem artichoke bread shows a high quality in organoleptic evaluation (grade I with 36.5 and 37.5 scores). In utilised Jerusalem artichoke powders (JAPs) the amount of fructan (inulin) hydrolysis to fructose during the baking process depends on its initial degree of polymerisation (dp). With JAP of autumn harvest (fructan: dpn = 9.9, dpw = 21.8) less fructose (24.6%) is formed than with those of spring harvest (fructan: dpn = 4.9, dpw = 7.1) (40.7%). Compared to this bread, substitution with commercial products Raftilin ST (inulin: dpn = 8.4, dpw = 17.4) and Raftilose P95 (fructo-oligosaccharides: dpn = 2.7, dpw = 3.0) yields 11.9% and 45.8% of fructose upon total hydrolysis, respectively. The loss of fructan content by the bakery process is 38% in bread with JAP of autumn and 43% in bread with JAP of spring harvest; Raftilin ST- and Raftilose P95-bread come up with loss of fructan content of 35% and 47%, respectively.

Bread↗
PubMed2000

Characterisation of the high-molecular weight fructan isolated from garlic (Allium sativum L.).

A high molecular weight fructan was isolated from garlic and the structure determined by enzymatic, chemical and spectroscopic (NMR) methods. It was found that the garlic fructan belongs to the neokestose family. It has a (2 --> 1)-linked beta-D-Fruf backbone with (2 --> 6)-linked beta-D-Fruf side chains. A structural model was postulated for a degree of polymerisation of about 58. This model was substantiated using an endo-inulinase purified from Aspergillus ficuum and by 1H and 13C NMR spectroscopy.

Aspergillus↗
PubMed1999

Structural characterization of the N-linked oligosaccharides from tomato fruit.

The primary structures of the N-linked oligosaccharides from tomato fruit (Lycopersicon esculentum) have been elucidated. For the isolation of the protein fraction, two procedures were employed alternatively: a low temperature acetone powder method and ammonium sulfate precipitation of the tomato extract. After peptic digestion, the glycopeptides were purified by cation-exchange chromatography; the oligosaccharides were released by N-glycosidase A and fluorescently labelled with 2-aminopyridine. Structural characterization was accomplished by means of two-dimensional HPLC in combination with exoglycosidase digestions and MALDI-TOF mass spectrometry. Two varieties as well as two stages of ripening were investigated. In all the samples, the same sixteen N-glycosidic structures were detected; the two most abundant glycans showed identical properties to those of the major N-linked oligosaccharides of horseradish peroxidase and pineapple stem bromelain, respectively and accounted for about 65-78% of the total glycan amount; oligomannosidic glycans occurred only in small quantities (3-9%). The majority of the N-glycans were beta 1,2-xylosylated and carried an alpha 1,3-fucose residue linked to the terminal N-acetylglucosamine. This structural element contributes to cross-reactions among non-related glycoproteins and has been shown to be an IgE-reactive determinant (Tretter, Altmann, Kubelka, März, & Becker, 1993). The presented study gives a possible structural explanation for reported immunological cross-reactivities between tomato and grass pollen extracts due to carbohydrate IgE epitopes (Petersen, Vieths, Aulepp, Schlaak, & Becker, 1996), thereby demonstrating the importance of the structural characterization of plant N-glycans for a more reliable interpretation of immunological data.

Carbohydrate Conformation↗
PubMed1997

A capillary electrophoretic study on the specificity of beta-galactosidases from Aspergillus oryzae, Escherichia coli, Streptococcus pneumoniae, and Canavalia ensiformis (jack bean).

The specificities of the beta-galactosidases from Aspergillus oryzae, Escherichia coli, Streptococcus pneumoniae, and Canavalia ensiformis (jack bean) have been studied by capillary zone electrophoresis. Various di- and oligosaccharides as well as a biantennary asialo N-glycan were used as substrates. Following enzymatic hydrolysis, the mixtures of substrates and products were derivatized with ethyl 4-aminobenzoate and separated by high-performance capillary electrophoresis in a borate buffer system using uv detection. Baseline separation of the respective peaks was obtained in 4 min, allowing the analysis of a large number of samples. Therefore, initial rates of hydrolysis could be determined. The beta-galactosidase from A. oryzae exhibited minimal activity toward Galbeta1-3GlcNAc. In contrast to the enzyme from S. pneumoniae which is almost specific for beta1-4 linkages, the Aspergillus galactosidase readily hydrolyzed Galbeta1-4GlcNAc and Galbeta1-6GlcNAc. Neither of the four beta-galactosidases acted upon Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-3Galbeta1-4Gl c (lacto-N-fucopentaose III) even though the corresponding nonfucosylated oligosaccharides were good substrates. With the exception of the enzyme from E. coli, the beta-galactosidases degalactosylated a biantennary N-linked oligosaccharide.

Aspergillus oryzae↗
PubMed1995

Purification of exo- and endoinulinase from crude inulinase extract for the analysis of fructans.

This paper describes a technique for rapid and easy separation of a crude inulinase extract into exo- and endoinulinase from a commercially available inulinase stock (Novozym 230 from Novo Nordisk A/S) by means of non-denaturating polyacrylamide gel electrophoresis. The purified enzymes were tested with inulin. Characterization of the reaction products was done by high-performance thin-layer chromatography, size exclusion chromatography and semi-preparative reverse-phase high-performance liquid chromatography.

Chromatography, High Pressure Liquid↗
PubMed1993

Fructo-oligosaccharides from Urginea maritima.

Fructo-oligosaccharides from red squill (Urginea maritima) were isolated by precipitation with methanol, GPC on Biogel P2/P4, and reversed-phase HPLC. Structures of the tri- and tetra-saccharides were verified by the reductive cleavage method. A tetrasaccharide that contained both (2-->1)- and (2-->6)-linked beta-D-Fru f residues was isolated. The higher fractions from GPC were analysed by the reductive cleavage method without prior purification by reversed-phase HPLC. The mode of biosynthesis of sinistrin is discussed.

Carbohydrate Conformation↗
PubMed1992

The structure of the fructan sinistrin from Urginea maritima.

The structure of sinistrin from red squill (Urginea maritima) was determined by methylation analysis and 13C NMR spectroscopy, using the fructans from Pucinella peisonis and quack-grass (Agropyron repens) as reference substances. Application of the reductive cleavage method showed that, of the beta-D-fructofuranosyl residues in sinistrin, 33% were 1-linked, 19% were 6-linked, 25% were terminal, and 19% were 1,6-linked. The average dp was 31 and, of the 3.24% of alpha-D-glucopyranosyl residues, 0.54% were terminal and 2.70% were 6-substituted. The fructan of quack grass was also highly branched with a (2-->6)-linked backbone, terminal alpha-D-glucopyranosyl residues, and a dp of approximately 45. The fructan from Pucinella peisonis was slightly branched, with a dp of approximately 10 and a (2-->6)-linked backbone.

Carbohydrate Conformation↗
PubMed1992

Fructo-oligosaccharides from the stems of Triticum aestivum.

Fructo-oligosaccharides, extracted with hot water from wheat stems before flowering, were fractionated by gel-permeation chromatography on Biogel P2. The tri-/tetra- and penta-saccharide fractions were purified by HPLC and analysed by the reductive cleavage method. The trisaccharides 1-kestose and 6-kestose, the branched tetrasaccharide bifurcose, and the (2-->6)-linked pentasaccharide were identified. The fractions of higher molecular weight were also investigated and confirmed the branched-levan structure of this fructan.

Carbohydrate Conformation↗