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G Widmalm

Publications and source records attributed to G Widmalm.

At least 73 records · Page 4Linked to original sources
PubMed1996

The structure of the exopolysaccharide produced by the halophilic Archaeon Haloferax mediterranei strain R4 (ATCC 33500).

The halophilic Archaeon Haloferax mediterranei exudes into the growth medium a high molecular weight sulfated polysaccharide. The structure of the repeating unit of this polymer was determined by a combination of glycose, methylation, and sulfate analysis, periodate oxidation, and 1D and 2D NMR spectroscopic analysis of the native and periodate-oxidised/reduced polysaccharides. The location of the sulfate group was established from the 1H and 13C NMR data. The structure of the repeating unit of the polysaccharide may be written as [formula: see text]

Acetylglucosamine↗
PubMed1996

Selective cleavage of welan gum (S-130) by oxidative decarboxylation with lead tetraacetate.

Oxidative decarboxylation of peracetylated welan gum (S-130) with lead tetraacetate resulted in selective cleavage of the glucuronosidic linkages. Products of the degradation were reduced with sodium borohydride, O-deacetylated, and fractionated. Polymeric and oligomeric fractions were separated and analysed by 1H NMR spectroscopy and fast atom bombardment mass spectrometry, and were found to be monomers, dimers, and trimers of the repeating unit. Results show that this method may be used to liberate alditol-terminated multiples of the repeating unit of peracetylated glycuronans by cleavage and degradation of the uronic acid residues. The reaction sequence also confirms the recent finding that welan gum contains repeating units with randomly distributed terminal groups.

Acetylation↗
PubMed1996

Structural elucidation of an extracellular polysaccharide produced by Lactobacillus helveticus.

An extracellular polysaccharide produced by a strain of Lactobacillus helveticus isolated from cheese milk has been investigated. Sugar and methylation analysis together with 1H and 13C NMR spectroscopy revealed that the polysaccharide is composed of hexasaccharide repeating units. The sequence of sugar residues was determined by use of two-dimensional nuclear Overhauser effect spectroscopy and heteronuclear multiple-bond correlation experiments. The structure of the repeating unit of the exopolysaccharide from L. helveticus is as follows: [sequence: see text]

Carbohydrate Conformation↗
PubMed1996

Structural studies of the O-antigenic polysaccharide from an Aeromonas caviae strain.

The structure of the O-antigenic polysaccharide from a strain of Aeromonas caviae, isolated from the stools of a patient with diarrhoea, has been investigated. Sugar analysis, methylation analyses, and a uronic acid degradation together with NMR spectroscopy were the principal methods used. The sequence of the sugar residues could be determined by NOESY and HMBC experiments. It is concluded that the polysaccharide is composed of pentasaccharide repeating units with the following structure: [sequence: see text]

Aeromonas↗
PubMed1996

Structural studies of the enteroinvasive Escherichia coli (EIEC) O28 O-antigenic polysaccharide.

The structure of the O-specific side-chain of the lipopolysaccharide from Escherichia coli O28 has been investigated. NMR spectroscopy has been the main method used, complemented with sugar and methylation analyses. The polysaccharide contains one equivalent of O-acetyl groups per repeating unit. Selective cleavage of the O-deacetylated polymer was performed by treatment with aqueous hydrofluoric acid, and resulted in a trisaccharide-glycerol. The polysaccharide thus is of the teichoic acid type and composed of repeating units in which the trisaccharide-glycerol residues are joined by phosphodiester linkages. The O-antigen polysaccharide has the following structure. [sequence: see text] The absolute configuration of the glycerol moiety as R, )i.e., D-glycerol 1-phosphate) was determined by a new method based on TEMPO oxidation of the polysaccharide, followed by GLC analysis of the (+)-2-butyl ester of the resulting glyceric acid.

Carbohydrate Conformation↗
PubMed1996

Structural analysis of the O-antigenic polysaccharide from the enteropathogenic Escherichia coli O125.

The structure of the polysaccharide part of the lipopolysaccharide obtained from the enteropathogenic Escherichia coli O125 has been investigated. Methylation analysis, 1H-NMR spectroscopy and 13C-NMR spectroscopy revealed that the polysaccharide is composed of repeating hexasaccharide units. Smith degradation of the native O-polysaccharide resulted in a polysaccharide with four sugar residues in the repeating unit. Information on the sequence of the native O-polysaccharide and the Smith-degraded product was obtained by two-dimensional techniques, namely heteronuclear-multiple-bond-connectivity and NOESY experiments. The structure of the repeating unit of the O-polysaccharide of E. coli strain O125, which has two adjacent branch-point residues, is [sequence: see text].

Carbohydrate Conformation↗
PubMed1996

Structural studies of the exocellular polysaccharide from Sphingomonas paucimobilis strain I-886.

The exocellular polysaccharide from Sphingomonas paucimobilis strain I-886 has been studied using methylation analysis, Smith degradation, partial acid hydrolysis, NMR spectroscopy, and mass spectrometry as the principal methods. It is concluded that the repeating unit has the following structure: [formula: see text] The absolute configuration of the uronic acid was deduced from 1H NMR chemical shifts and is most likely D. Some preparations of the polysaccharide also contain phosphate and O-acyl groups which have not been identified or localised.

Carbohydrate Conformation↗
PubMed1996

A Klebsiella pneumoniae strain that shares a type-specific antigen with Shigella flexneri serotype 6. Characterization of the strain and strain and structural studies of the O-antigenic polysaccharide.

A strain of Klebsiella pneumoniae was found as the only isolate with pathogenic potential from the stool of a two-year old patient with diarrhoea. A strong serological cross-reactivity with Shigella flexneri serotype 6 was demonstrated. The cross-reacting antigens were shown to reside in the cell wall lipopoly-saccharide. Studies of the pathogenic potential of the Klebsiella strain showed low level of invasion of HEp-2 cells. However, tests for adherence to HEp-2 cells as well as tests for toxin production were negative. The strain had several small plasmids and was multidrug resistant. These data do not form a sufficient basis for estimating the pathogenic potential of the organism. No K antigen was detected. The structure of the O-antigenic polysaccharide from the K. pneumoniae strain was investigated using methylation analysis, NMR spectroscopy, and Smith degradation as the principal methods. The O-antigenic polysaccharide has the following pentasaccharide repeating unit: -->3)- alpha -L-Rhap-(1-->3)- alpha -L-Rhap-(1-->2)- alpha-L-Rhap- (1-->2)- alpha-L-Rhap-(1-->2)- alpha-L-Rhap-(1-->. This structure is not identical to any of the previously described O-antigens of K. pneumoniae. The strong serological cross-reactivity with the Shigella flexneri serotype 6 O-antigen can most likely be attributed to the structural element alpha-L-Rhap-(1-->2)- alpha -L-Rhap present in the O-polysaccharide repeating unit of this serotype. Antiserum raised against the K. pneumoniae strain also agglutinated S. dysenteriae serotype 1 and strains of all different serotypes of S. flexneri. The Shigella strains contain the structural element alpha-L-Rhap-(1-->3)- alpha-L-Rhap in their O-antigen polysaccharides which may be responsible for the observed cross-reactivity.

Bacterial Adhesion↗
PubMed1996

Structural studies of the Escherichia coli O26 O-antigen polysaccharide.

The structure of the O-specific side chain of the E. coli O26 lipopolysaccharide has been investigated. Based on sugar and methylation analyses, and 2D NMR spectroscopy employing HMBC experiments, it is concluded that the polysaccharide is composed of trisaccharide repeating units having the following structure. -->3)-alpha-L-Rhap-(1-->4)-alpha-L-FucpNAc-(1-->3)-beta-D-Gl cpNAc-(1-->

Acetylglucosamine↗
PubMed1996

Motional properties of a pentasaccharide containing a 2,6-branched mannose residue as studied by 13C nuclear spin relaxation.

13C relaxation data obtained at three different magnetic fields, 9.4, 11.8 and 14.1 T, and at two temperatures, 303 and 318 K, are reported for the pentasaccharide p-trifluoroacetamidophenyl 2,6-di-O-[beta-D-galactopyranosyl-(1-->4)-O-2-acetamido-2-deoxy-beta-D- glucopyranosyl] alpha-D-mannopyranoside. The pentasaccharide consists of two disaccharide units, attached at positions 2 and 6 to the central mannopyranoside residue. The relaxation data were interpreted with the Lipari-Szabo model-free approach. For the central mannose residue in the molecule a high order parameter (S2 = 0.91) was found and the relaxation data could be interpreted with the truncated form of the Lipari-Szabo model. The motional behavior of the two 2-acetamido-2-deoxy-glucopyranoside residues was found to differ. The one attached at the primary hydroxylic position displayed more extensive local motion (S2 = 0.75-0.77) than the one attached at the secondary hydroxylic position (S2 = 0.83-0.85). More extensive local motion for the two outer galactopyranoside residues was found (S2 = 0.56-0.59), but no significant difference in motional behavior between the two residues could be observed. Analysis of the relaxation data for the exocyclic carbons confirmed the results for the rings. For the mannose C6, the same motional parameters as obtained for the substituting 2-acetamido-2-deoxy-glucopyranoside residue were found. The two exocyclic carbons on the 2-acetamido-2-deoxy-glucopyranoside residues showed more extensive local motion, with lower order parameters (S2 = 0.59-0.66).

Carbohydrate Conformation↗
PubMed1996

Isolation and characterization of a trisulfide variant of recombinant human growth hormone formed during expression in Escherichia coli.

A new variant of human growth hormone was recently found [Pavlu, B. & Gellerfors, P. (1993) Bioseparation 3, 257-265]. We report here the identification and the structural determination of this variant. The variant, which is formed during the expression of human growth hormone in Escherichia coli, was found to be more hydrophobic than rhGH as judged by its prolonged elution time by hydrophobic interaction chromatography. The rhGH hydrophobic variant (rhGH-HV) was isolated and subjected to trypsin digestion and RP-HPLC analysis, resulting in an altered retention time of one single tryptic peptide as compared to the corresponding fragment of rhGH. This tryptic peptide constitutes the C-terminus (aa 179-191) of hGH and contains one of the two disulfide bridges in hGH, viz. Cys182-Cys189. Amino acid sequences and composition analyses of the tryptic peptide from rhGH-HV (Tv18-19) and the corresponding tryptic peptide from rhGH (T18+19) were identical. Electrospray mass spectrometry (ES MS) of Tv18+19 isolated from rhGH-HV revealed a monoisotopic mass increase of 32.7, as compared to T18+19 from rhGH. A synthetic Tv18+19 peptide having a trisulfide bridge between Cys182 and Cys189 showed identical fragment in ES/MS compared to Tv18+19 isolated from rhGH-HV, i.e. m/z 617.7 and 682.9. These fragments are formed through a unique cleavage in the trisulfide (Cys182-SSS-Cys189) bridge not found in the corresponding T18+19 disulfide peptide. Furthermore, the synthetic Tv18+19 co-eluted in RP-HPLC with Tv18+19 isolated from rhGH-HV. Two-dimensional NMR spectroscopy of the synthetic T18+19 and Tv18+19 peptides were performed. Using these data all protons were assigned. The major chemical shift changes (delta delta > 0.05 ppm) observed were for the beta-protons of Cys182 and Cys189 in Tv18+19 as compared to T18+19. CD spectroscopy data were also in agreement with the above results. Based on these physico-chemical data rhGH-HV has been structurally defined as a trisulfide variant of rhGH. The receptor binding properties of rhGH-HV was studied by a biosensor device, BIAcore. The binding capacity of rhGH-HV was similar to rhGH with a binding stoichiometry to the rhGHBP of 1:1.6 and 1:1.5, respectively, indicating that the trisulfide modification did not affect its receptor binding properties.

Amino Acid Sequence↗
PubMed1995

Structural elucidation of the O-antigenic polysaccharide from Escherichia coli O44:H18.

The O-antigen polysaccharide of the lipopolysaccharide from the enteroaggregative Escherichia coli O44:H18 has been investigated. Sugar and methylation analysis, 1H- and 13C-NMR spectroscopy revealed that the polysaccharide is composed of pentasaccharide repeating units. The sequence of sugar residues was determined by use of two-dimensional nuclear Overhauser effect spectroscopy and heteronuclear multiple bond correlation experiments. The structure of the repeating unit of the O-antigen from Escherichia coli O44:H18 is as follows. [formula: see text]

Carbohydrate Sequence↗
PubMed1995

Structure of the capsular polysaccharide of Vibrio cholerae O139 synonym Bengal containing D-galactose 4,6-cyclophosphate.

The capsular polysaccharide (CPS) of Vibrio cholerae O139 synonym Bengal, which is thought to carry determinants of O-specificity, was isolated by phenol/water extraction followed by delipidation of the contaminating lipopolysaccharide at pH 4.2 and gel-permeation chromatography. The CPS contained D-galactose, 3,6-dideoxy-L-xylo-hexose (colitose, Col), 2-acetamido-2-deoxy-D-glucose, 2-acetamido-2,6-dideoxy-D-glucose (N-acetyl-D-quinovosamine, D-QuiNAc), D-galacturonic acid (D-GalA), and phosphate. The CPS was studied by NMR spectroscopy, methylation analysis, and selective degradations, including partial acid hydrolysis at pH 3.1 and dephosphorylation with aqueous 48% hydrofluoric acid, which both resulted in complete cleavage of Col. It was concluded that the CPS is built up of hexasaccharide repeating units containing inter alia D-galactose 4,6-cyclophosphate and having the following structure [structure: see text] These data basically confirm the structure of the V. cholerae CPS proposed on the basis of an NMR study [L. M. Preston et al. (1995) J. Bacteriol. 177, 835-838] and specify exactly the absolute configurations of the constituent monosaccharides and the position of the cyclic phosphate.

Carbohydrate Sequence↗
PubMed1995

Structure of the capsular polysaccharide from the Klebsiella K8 reference strain 1015.

The structure of the capsular polysaccharide from the Klebsiella K8 reference strain 1015 has been elucidated. The structure was deduced from sugar analysis, different methylation analyses, a uronic acid degradation, and NMR spectroscopy. It is concluded that the polysaccharide is composed of pentasaccharide repeating units with the structure: [formula: see text] The structure differs from that of the previously published structure of the capsular polysaccharide from Klebsiella K8, which originates from another strain and has the following structure: [formula: see text] The serological similarity between the two strains is most likely derived from a common tetrasaccharide which is substituted in different ways in the two strains. Since the strain in the present investigation originates from the Klebsiella K reference strain collection of the International Escherichia and Klebsiella Centre, Copenhagen, Denmark, it is suggested that it should keep the designation K8. The other polysaccharide with Klebsiella K8 specificity should be renamed as K8,52,59 based on the cross-reactivity of the strain (I. Orskov, unpublished).

Bacterial Capsules↗
PubMed1995

Structural studies of the capsular polysaccharide from Klebsiella type 7.

The structure of the capsular polysaccharide elaborated by Klebsiella type 7 has been investigated. NMR spectroscopy together with sugar and methylation analysis have been the main methods used. A uronic acid degradation was also employed. The polysaccharide consists of hexasaccharide repeating units having the following structure. [formula: see text]

Bacterial Capsules↗
PubMed1995

Structural elucidation of the O-antigen lipopolysaccharide from two strains of Plesiomonas shigelloides that share a type-specific antigen with Shigella flexneri 6, and the common group 1 antigen with Shigella flexneri spp and Shigella dysenteriae 1.

Sugar and methylation analyses of native polysaccharides together with one-dimensional 1H- and 13C-NMR spectroscopy revealed that the two polysaccharides from strains 22074 and 12254 of Plesiomonas shigelloides are identical. The structure of the polysaccharide from strain 22074 was deduced from a uronic acid degradation and by NMR spectroscopy where heteronuclear multiple bond connectivity and two-dimensional nuclear Overhauser effect spectroscopy experiments established the pentasaccharide repeating unit as-->4)-alpha-D-GalpA-(1-->3)-alpha-D-GlcpNAc-(1-->3)-alpha-L- Rhap-(1-->2)-alpha-L-Rhap-(1-->2)-alpha-L-Rhap-(1-->.

Antigens, Bacterial↗
PubMed1995

Structure of an acidic microcapsular glycan from the reference strain (C.D.C. 866-57) for Serratia marcescens serogroup O1.

The structure of the acidic polysaccharide from Serratia marcescens serogroup O1 has been investigated. NMR spectroscopy together with sugar and methylation analysis have been used as well as a uronic degradation. The polysaccharide consists of pentasaccharide repeating units having the following structure. (sequence see text) The polysaccharide also contains one equivalent of O-acetyl groups per repeating unit present on, inter alia, a hydroxymethyl group.

Acetylglucosamine↗