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Biomedical subjects

O Holst

Publications and source records attributed to O Holst.

98 records · Page 6Linked to original sources
PubMed1990

Characterization of murine monoclonal and murine, rabbit, and human polyclonal antibodies against chlamydial lipopolysaccharide.

Murine monoclonal and rabbit, murine, and human polyclonal antibodies against chlamydial lipopolysaccharide (LPS) were characterized by the passive hemolysis and passive hemolysis inhibition assays and by absorption experiments with LPSs of Chlamydia psittaci, Chlamydia trachomatis, and a recombinant strain of Salmonella minnesota Re (r595-207) expressing the chlamydia-specific LPS epitope, as well as natural and synthetic partial structures of chlamydial LPS. Eleven monoclonal antibodies of the immunoglobulin M and G classes were characterized as chlamydia-specific by their failure to react with Re-type LPS, binding to a similar epitope for which the trisaccharide alpha-3-deoxy-D-manno-2-octulosonic acid (KDO)-(2-8)-alpha-KDO-(2-4)-alpha-KDO was an absolute prerequisite. For optimal binding, parts of the lipid A moiety were also involved; however, phosphoryl and ester-linked acyl groups and the reducing glucosamine residue of lipid A were dispensable. A similar antibody specificity was detected in lapine and murine hyperimmune sera after immunization with chlamydia, in addition to those recognizing more complex (e.g., those requiring the presence of phosphoryl residues) and less complex epitopes. Among the latter were those cross-reacting with Re-type LPS, which could be removed by absorption. The titers of different antibody specificities, in particular the ratio of chlamydia-specific to cross-reactive antibodies, present in murine polyclonal antisera depended on the immunization protocol. The preferential formation of chlamydia-specific antibodies was observed after immunization with liposome-incorporated immunogens. Human sera from patients with suspected genital chlamydial infections were also found to contain chlamydia-specific and cross-reactive antibodies, the latter of which could be removed by absorption with Re-type LPS.

Antibodies, Bacterial↗
PubMed1989

A phosphodiester bridge between two arabinose residues as a structural element of an extracellular glycoprotein of Volvox carteri.

The sulphated glycoprotein SSG 185 is the monomeric precursor of a highly aggregated structural element in the extracellular matrix of the multicellular green alga Volvox carteri. A phosphodiester of arabinose was isolated from a saccharide fragment of SSG 185. The structure of this phosphodiester was investigated by methylation analysis, 13C-NMR, photometric methods and enzymatic assays and identified as D-Araiota-5-phospho-5-D-Araiota. The function of this phosphodiester bridge as a crosslink of different carbohydrate chains in SSG 185 is discussed.

Arabinose↗
PubMed1985

Prokaryotic triterpenoids. The hopanoids of the purple non-sulphur bacterium Rhodomicrobium vannielii: an aminotriol and its aminoacyl derivatives, N-tryptophanyl and N-ornithinyl aminotriol.

Triterpenoids belonging to the hopane family are widely distributed in prokaryotes. Three new hopanoids have now been isolated from the purple non-sulphur bacterium Rhodomicrobium vannielii and identified essentially by spectroscopic methods. The basic compound is the 35-aminobacteriohopane-32,33,34-triol, from which the other two hopanoids are derived by introduction of a tryptophanyl or an ornithinyl moiety linked to the amino group at C-35 via an amide linkage. This is the first report of hopanoids possessing an amino group in their side-chain and linked to aminoacyl residues.

Chemical Phenomena↗
PubMed1983

Structural studies on the phosphate-free lipid A of Rhodomicrobium vannielii ATCC 17100.

The structure of the free lipid A from Rhodomicrobium vannielii ATCC 17100 was elucidated. It consists of a central beta-1',6-linked glucosamine disaccharide which is not substituted by phosphate. About 30% of the disaccharide molecules are substituted with mannopyranose in beta-1,4'-linkage to the non-reducing glucosamine. The reducing glucosamine can be directly reduced with NaBH4, indicating either that this glucosamine is not substituted at C1 or its substituent has been removed during the preparation of free lipid A or is removed during reduction with NaBH4. The following formula shows the 'backbone' structure of the free lipid A from Rm. vannielii ATCC 17100: beta-Manp(1-- leads to 4)-beta-GlcpN(1 leads to 6)GlcpN. 3-(R)-Hydroxyhexadecanoic acid is linked to the amino group of the reducing glucosamine. The residue at the amino group of the non-reducing glucosamine has not been identified. The hydroxyl groups of the central disaccharide are acylated with 3-(tetradecanoyloxy)-tetradecanoic acid, 3-hydroxytetradecanoic acid, delta 14-docosenoic acid (delta 14-C22:1) and acetyl groups. The hydroxyl groups of the mannose are not substituted.

Amides↗
PubMedDate not supplied

Unusual lipid A types in phototrophic bacteria and related species.

Photosynthetic bacteria of the Rhodospirillaceae family (sulfur-free purple bacteria) possess lipopolysaccharides (LPS) that deviate markedly from the Salmonella lipopolysaccharides in the chemical makeup of the lipid A component and in their biologic properties. LPS of Rhodopseudomonas gelatinosa is highly toxic and pyrogenic, while that of Rhodospirillum tenue shows cryptic toxicity. Two LPS types are completely non-toxic. The Rhodopseudomonas sphaeroides lipid A has the same backbone as that of Salmonella, but a part of the amide-linked fatty acids has the unusual 3-oxo structure (3-oxo-14:0). The lipid A's of Rhodopseudomonas viridis and Rhodopseudomonas palustris have 2,3-diamino-2,3-dideoxy-D-glucose as the backbone sugar. This is the first demonstration of this sugar in nature. In recent studies using 16S rRNA sequencing, the nonphotosynthetic Nitrobacter strains were shown to be phylogenetically closely related to R. palustris. The R. palustris lipid A type has been identified in three Nitrobacter species, including Nitrobacter winogradskyi, the type strain. The data demonstrate the taxonomic significance of lipid A constituents and structures.

Bacteria↗