PubMed Health⌕ Search

Biomedical subjects

P Prehm

Publications and source records attributed to P Prehm.

47 records · Page 3Linked to original sources
PubMed1978

Citrobacter O-antigens: structure of the O-antigenic polysaccharide from Citrobacter sp. 396.

The structure of the O-specific polysaccharide moiety of the lipopolysaccharide from Citrobacter 396 was elucidated by composition, methylation, and periodate oxidation studies. The repeating unit consists of four 2-linked mannoses and one 3-linked N-acetylglucosamine. One of the mannose units is substituted at C3 with alpha-glucose, and one is substituted at C3 with alpha-(2-O-acetyl)-abequose. All the mannosyl linkages appear to have the beta-configuration; the N-acetylglucosaminyl linkage has the alpha-configuration. In bacterial agglutination and passive hemagglutination in some Salmonella antisera, Citrobacter 396 as well as its O-antigenic lipopolysaccharide expressed the serological factors 5 and 6. In corroboration of our structural studies, this showed the presence of alpha-(2-O-acetyl)-abequosyl-1,3-mannose (factor 5) and alpha-glucosyl-1,3-mannose (factor 6).

Antigens, Bacterial↗
PubMed1976

The cell-wall lipopolysaccharide of Escherichia coli K-12. Structure and acceptor site for O-antigen and other substituents.

The lipopolysaccharides of two wild-type Escherichia coli K-12 strains, two core-deficient mutants and one SR recombinant with Salmonella typhimurium specificity were analyzed. The respective oligosaccharides were dephosphorylated and methylated. Chemical analysis of the oligosaccharides and mass spectrometric analysis of their methylated derivatives indicated the presence of core structures with different degrees of completion. In different strains of E. coli K-12 the complete core is substituted at the non-reducing end with N-acetylglucosamine or with another substituent. There are indications that the latter may be N-acetylmannosaminuronic acid. In the SR recombinant the complete (N-acetylglucosamine-free) K-12 core is substituted with one S-specific oligosaccharide of S. typhimurium. The attachment site for all these substituents is the 6-position of the non-reducing core-terminal glucose. The heterogeneity of the K-12 core preparations and mode and nature of their substitution are discussed.

Antigens, Bacterial↗
PubMed1976

The O9 antigen of Escherichia coli. Structure of the polysaccharide chain.

The lipopolysaccharide from Escherichia coli O9:K30- was isolated in about 2% yield with aqueous 45% phenol at 65 degrees C, followed by ultracentrifugation. The polysaccharide moiety was obtained by graded hydrolysis and gel permeation chromatography. It consisted of a mannan which carried on its reducing end the core oligosaccharide of the R1 type. The mannan contained 1 leads to 2 and 1 leads to 3 linkages in a ratio of 3:2, as determined by methylation analysis and mass spectrometry. On periodate oxidation, 58% of the mannose residues were destroyed. Degradation of oligosaccharide mixtures with alpha-mannosidase from jack bean meal, as well as a specific rotation of [alpha]25D = +89 degrees indicated that all mannosyl linkages have the alpha-configuration. Smith degradation resulted in the liberation of mannosyl (1 leads to 3)-mannose (bound to glyceraldehyde), as established by methylation analysis. From these results we conclude that the O9 polysaccharide of E. coli has a pentasaccharide repeating unit of alpha-mannosyl(1 leads to 3)-alpha-mannosyl-(1 leads to 2)-alpha-mannosyl-(1 leads to 2)-alpha-mannosyl-(1 leads to 2)-mannose, which are joined in the polysaccharide through alpha-(1 leads to 3)-mannosyl linkages.

Chromatography, Gas↗
PubMed1976

Cell-wall lipopolysaccharides of ampicillin-resistant mutants of Escherichia coli K-12.

The lipopolysaccharides of ampicillin-resistant cell-wall-defective mutants of Escherichia coli K-12 were analyzed. From their lipopolysaccharides the respective core oligosaccharides were obtained. Following dephosphorylation,the core oligosaccharides were methylated and analyzed by gas chromatography/mass spectrometry. From core-defective mutants substructures of the K-12 core were obtained. Analysis of the lipopolysaccharide preparations from wild-type K-12 indicated the presence of several core structures with different degrees of completion. The lipopolysaccharide preparation was degraded and the oligosaccharide mixture was partially resolved by gel filtration chromatography. Methylation, gas chromatography and mass spectrometry of the oligosaccharides permitted the tentative formulation of the K-12 core structure. Alternative interpretations for this heterogeneity are discussed.

Ampicillin↗
PubMed1976

Enzymatic action of coliphage omega8 and its possible role in infection.

The receptor of coliphage omega8 is the O-specific mannan of Escherichia coli O8 in which the trisaccharide alpha-mannosyl-1,2-alpha-mannosyl-1,2-mannose is joined through alpha-mannosyl-1,3-linkages. Coliphage omega8 produces an endo-alpha-1,3-mannosidase which destroys the receptor, liberating a series of oligosaccharides (repeating trisaccharide and multiples). The enzyme is an integral part of the phage particles and also occurs in a free form in the lysates. Phage particles hydrolyze alpha-1,3-mannosyl linkages in the lipopolysaccharide, the polysaccharide (mannan) moiety, and higher oligosaccharides with an efficiency decreasing in this order. No transmannosylation could be detected. Phage particles also degrade the receptor mannan on whole bacteria, as determined with 14C-labeled E. coli O8. The values of Km and Vmax were determined with omega8 particles and free enzymes using native lipopolysaccharide and its triethylammonium salt. The latter, which was obtained after electrodialysis, has a micellar weight of 2.5 X 10(5), whereas the native lipopolysaccharide forms supermicelles with micellar weights of several millions. With coliphage omega8 as enzyme and supermicellar lipopolysaccharide as substrate Km=5 X 10(-8) M was obtained. This, together with the fact that omega8 attaches irreversibly to E. coli O8, was used in proposing a hypothesis for the possible role of the enzyme in the first steps of infection with coliphage omega8.

Adsorption↗
PubMed1975

Cell-wall lipopolysaccharide from Escherichia coli B.

The lipopolysaccharide of Escherichia coli BB and a number of R-phage selected (e.g. T3, T4) cell-wall-defective mutants were analyzed. From their lipopolysaccharides the respective core oligosaccharides were obtained. Following dephosphorylation, the oligosaccharides were methylated and analyzed by gas chromatography/mass spectrometry. This revealed the sugar sequence in the hexose-heptose region of the core. The linkage of heptose (Hep) to 2-keto-3-deoxyoctonate (KDO) was established as ... Hep 1,5 leads to KDO ... by methylation analysis. The substituted derivative of KDO was identified by gas chromatography and mass spectrometry. The KDO region contains three KDO units. Its structure was elaborated by (a) selective removal and identification of 7-phosphoryl ethanolamine-KDO (KDO-PN), (b) periodate oxidation and thiobarbituric acid reaction in conjunction with mild hydrolysis, (c) a modified methylation analysis. Phosphate substitution of E. coli BB core was studied by beta-elimination and using the information obtained with KDO-PN. The structures of the cell wall lipopolysaccharides from E. coli BB and cell-wall-defective mutants are given.

Chromatography, Gas↗