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  • 1
    Electronic Resource
    Electronic Resource
    Polymyxin B induces transient permeability fluctuations in asymmetric planar lipopolysaccharide/phospholipid bilayers (1992)
    s.l. : American Chemical Society
    Biochemistry 31 (1992), S. 631-638 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00118a001
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  • 2
    Electronic Resource
    Electronic Resource
    Laser desorption mass spectrometry of nonvolatiles under shock wave conditions (1985)
    s.l. : American Chemical Society
    Analytical chemistry 57 (1985), S. 895-899 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00281a027
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  • 3
    Electronic Resource
    Electronic Resource
    Pore formation by complement in the outer membrane of Gram-negative bacteria studied with asymmetric planar lipopolysaccharide/phospholipid bilayers (1990)
    Springer
    The journal of membrane biology 118 (1990), S. 161-170 
    Details
    ISSN: 1432-1424
    Keywords: outer membrane ; planar lipid bilayer ; lipopolysaccharide ; complement ; pore formation ; membrane reconstitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The interaction of complement with an asymmetric planar lipopolysaccharide/phospholipid bilayer system as a model for the lipid matrix of the outer membrane of Gram-negative bacteria has been studied. The addition of whole human serum to the aqueous solution at the lipopolysaccharide side of the asymmetric membrane resulted in a rapid increase of the bilayer conductance in discrete steps, indicating the formation of transmembrane pores, which were not observed in the case of pure phospholipid membranes. The amplitudes of the discrete conductance steps varied over a range of more than one order of magnitude. The mean single step conductance was (0.39±0.24) nS for a subphase containing (inmm): 100 KCl, 5 MgCl2 and 5 HEPES buffer. The steps were grouped into bursts of typically 9±3 events per burst and the conductance change within one burst was (8.25±4.00) nS. The pore-forming activity of serum at the asymmetric membrane system was independent of the presence of specific antibodies against the lipopolysaccharide but was dependent on calcium ions. Furthermore, the pore-forming activity required complement component C9. A model for the mode of pore formation by complement is proposed: The complement pore is generated in discrete steps by insertion of C9 monomers into the membrane and their irreversible aggregation to water-filled channels with a diameter of approximately 7 nm assuming a circular geometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868473
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  • 4
    Electronic Resource
    Electronic Resource
    Reconstitution of the lipid matrix of the outer membrane of Gram-negative bacteria as asymmetric planar bilayer (1989)
    Springer
    The journal of membrane biology 109 (1989), S. 95-103 
    Details
    ISSN: 1432-1424
    Keywords: outer membrane ; planar lipid bilayer ; lipopolysaccharide ; α-toxin ; membrane reconstitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary This paper is a report on the reconstitution of the lipid matrix of the outer membrane of Gram-negative bacteria as an asymmetric planar bilayer. This is the first time that a planar membrane is described, which consists on one side of a phospholipid (PL) mixture and on the other side of lipopolysaccharide (LPS). Therefore, strong emphasis is placed on a physical characterization of this membrane via its electrical properties. The membranes were prepared from spread monolayers or from vesicle-derived monolayers. Contrary to observations for symmetric phospholipid membranes, specific capacitances of (0.67±0.02) μF·cm−2, breakdown voltages between 200 and 400 mV and specific conductances between 10−8 and 2×10−7S·cm−2 were obtained independent of the preparation method. The LPS-containing membranes were stable up to 3 hr if they were formed and kept at temperatures above the hydrocarbon chain melting temperature of the LPS. For the specific capacitance, a dependence on the aperture radius was observed. This is explained by assuming a toroidal transition zone at the rim of the aperture. First results on the action of the pore-forming α-toxin fromStaphylococcus aureus on bilayers of different composition demonstrate particular characteristics of this asymmetric bilayer system. The pore-formation rate is highest in symmetric phospholipid bilayers, considerably lower in asymmetric PL/LPS systems and fully inhibited in LPS/LPS systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870848
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  • 5
    Electronic Resource
    Electronic Resource
    Isolation and structural analysis of two lipid A precursors from a KDO deficient mutant of Salmonella typhimurium differing in their hexadecanoic acid content (1985)
    Springer
    Archives of microbiology 141 (1985), S. 353-358 
    Details
    ISSN: 1432-072X
    Keywords: KDO mutant ; Lipid A intermediates ; Hexadecanoic acid substitution ; Biosynthesis of lipid A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The extraction, purification and structural characterization of two lipid A precursors (Ia and Ib) differing only in one hexadecanoic acid are described. Both precursors were synthesized at elevated temperatures by a new mutant of Salmonella typhimurium (mutant Ts5) which is conditionally defective in synthesis of the 3-deoxy-d-manno-octulosonic acid region of lipopolysaccharides. Both precursors were purified by repeated phenol/chloroform/petroleum ether (PCP) extractions followed by thin layer chromatography. Teh precursor preparation was free of lipopolysaccharides and phospholipids and contained less than 0.1% protein. Structural analysis which included chemical degradation procedures as well as positive ion laser desorption (LDMS) mass spectroscopy of dephosphorylated lipid A precursors showed together that precursor Ia represents a diphosphorylated glucosamine disaccharide containing two ester, two amide-linked residues of 3-hydroxytetradecanoic acid and lacks the ester-linked dodecanoic, tetradecanoic and hexadecanoic acid as well as 3-deoxy-d-manno-octulosonic acid. Precursor Ib has the same basic structure as precursor Ia, but contains in addition one mol of hexadecanoic acid per mol disaccharide which is linked to the 3-hydroxy group of the amide-bound 3-hydroxy-tetradecanoic acid of the reducing, terminal glucosamine residue. The structure of precursor Ib supports the conclusion that hexadecanoic acid incorporation occurs at an early stage in lipid A biosynthesis prior to the attachment of 3-deoxy-d-manno-octulosonic acid and/or other polar substituents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428849
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  • 6
    Electronic Resource
    Electronic Resource
    Chemical studies on the lipopolysaccharide of Rhizobium meliloti 10406 and its lipid A region (1989)
    Springer
    Archives of microbiology 152 (1989), S. 527-532 
    Details
    ISSN: 1432-072X
    Keywords: Fast growing rhizobia ; Lipid A ; 3-Hydroxy-octadecenoic acid ; 27-Hydroxyoctacosanoic acid ; Rhizobium meliloti
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The structure of the lipopolysaccharide from Rhizobium meliloti 10406, a derivative of the wild-type strain MVII-1, was examined. The compositional analysis of its polysaccharide moiety demonstrated lack of heptose(s), but high contents in glucose, galacturonic acid and 2-keto-3-deoxy-octonate (dOclA) as characteristic features. The lipid A moiety consisted of a β-1,6 linked glucosamine disaccharide carrying ester (at C-4′) and glycosidically (at C-1) linked phosphate residues, both present exclusively as monoester phosphates but not as phosphodiesters. Ester- and amidelinked 3-hydroxy fatty acids were mostly present as non-3-O-acylated residues. Laser desorption mass spectrometry (LD-MS) revealed heterogeneity in the fatty acid substitution, as was also indicated by the non-stoichiometric ratios obtained by quantitative fatty acid analysis. The predominating lipid A structure contained at the reducing glucosamine residue ester-linked 3-hydroxy-tetradecanoic acid (3-OH-14:0) and amide-linked 3-OH-18:0, or 3-OH-18:1, respectively. The distal (non-reducing) glucosamine carried ester-bound the recently discovered 27-hydroxyoctacosanoic acid and 3-OH-14:0 and, as amide-linked fatty acid, mostly 3-hydroxy-stearic acid (3-OH-18:0). The isolated lipopolysaccharide exhibited a high extent of lethal toxicity in galactosamine-treated mice, comparable to that of enterobacterial lipopolysaccharide. The structural relationship of LPS and lipid A of Rhizobium meliloti to other rhizobial lipopolysaccharides and lipid A's with respect to questions of taxonomy and of phylogenetic relationships will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425481
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  • 7
    Electronic Resource
    Electronic Resource
    Lipopolysaccharide of Rhodospirillum salinarum 40: structural studies on the core and lipid A region (1995)
    Springer
    Archives of microbiology 164 (1995), S. 280-289 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsRhodospirillum salinarum ; Lipopolysaccharide ; Mixed lipid A ; 2 ; 3-Diamino-2 ; 3-dideoxy-d-glucose ; 4-O-Methyl- ; galacturonic acid ; Halophilic bacteria ; Lethal toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The structural elucidation of lipid A of the cell wall lipopolysaccharide (LPS) of Rhodospirillum salinarum 40 by chemical methods and laser desorption mass spectrometry revealed the presence of a mixed lipid A composed of three different 1,4′bisphosphorylated β(1→6)-linked backbone hexosaminyl-hexosamine disaccharides, i.e. those composed of GlcN→GlcN, 2,3-diamino-2,3-dideoxy-d-Glc-(DAG)→DAG, and DAG→GlcN. Lipid A of R. salinarum contained preferentially 3-OH-18 : 0 and 3-OH-14 : 0 as amide-linked and cisΔ11–18 : 1 and c19 : 0 as ester-linked fatty acids. The mass spectra of the liberated acyl-oxyacyl residues proved the concomitant presence of 3-O-(cisΔ11–18 : 1)–18 : 0 and 3-O-(c19 : 0)-14 : 0 as the predominating diesters in this mixed lipid A. The glycosidically linked and the ester-linked phosphate groups of the backbone disaccharide were neither substituted by ethanolamine, phosphorylethanolamine, nor by 4-amino-4-deoxy-l-arabinose, in contrast to most of the enterobacterial lipid As. In the core oligosaccharide fraction, a HexA (1→4)HexA(1→5)Kdo-trisaccharide was identified by methylation analysis. The terminal HexA (hexuronic acid) is possibly 4-OMe-GalA, a component described here as an LPS constituent for the first time. LPS of R. salinarum showed a lethality in C57BL/10 ScSN (LPS-responder)-mice) of an order of 10–1–10–2 of that reported for Salmonella abortus equi LPS, and it was also capable of inducing TNFα and IL6 in macrophages of C57BL/10ScSN mice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050265
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  • 8
    Electronic Resource
    Electronic Resource
    Nucleolar organizer regions (Ag-NORs) in multinuclear osteoclasts (1998)
    Springer
    Journal of bone and mineral metabolism 16 (1998), S. 227-233 
    Details
    ISSN: 1435-5604
    Keywords: Key words: osteoclasts ; nucleolar organizer regions ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: Osteoclasts are multinuclear bone-resorbing cells. Little is known about regulation of gene expression in these cells and how it changes during the aging of an osteoclast, which is indicated by an increasing number of nuclei. Silver staining of nucleolar organizer regions, so-called Ag-NORs, allows us to assess the activity of rRNA expression. Using this technique, we show that individual nuclei of osteoclasts can be stained specifically and that the majority of individual nuclei contained Ag-NORs. The number and size of Ag-NORs varied, indicative of difference in the progression of the cell cycle through the G1 phase. The relative activity of Ag-NORs was not synchronized on the level of individual nuclei, regardless of the number of nuclei per osteoclast. Surprisingly, the total activity of Ag-NOR appeared to be correlated to the total nuclear area of an osteoclast. We conclude that regulation of gene expression in multinuclear osteoclasts most likely occurs on the level of individual nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007740050049
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  • 9
    Electronic Resource
    Electronic Resource
    Laser desorption mass spectrometry of synthetic lipid a-like compounds (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 132-141 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The applicability and the present limitations of the laser microprobe mass analyser LAMMA®-500 as an instrument for the structural analysis of higher molecular weight, non-volatile, bio-organic compounds (≤2000 u) were investigated. For this purpose mass spectra of various synthetic and natural compounds representing cell wall components of Gram-negative bacteria, e.g. phospholipids and lipid A-like molecules were studied. In several cases these spectra exhibited relatively simple and interpretable patterns with a prominent quasi-molecular ion originating from alkali attachment. For one group of the compounds studied - synthetic lipid A-like molecules containing a phosphate moiety - the spectra were rather complicated and lacked pronounced quasi-molecular peaks. Possible reasons for this observation are discussed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200110308
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  • 10
    Electronic Resource
    Electronic Resource
    Monitoring of bacterial drug response by mass spectrometry of single cells (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 16 (1988), S. 457-459 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The application of the laser microprobe mass analyser LAMMA 500 to the solution of problems in the field of microbiology is reported. The special features of this instrument allow the analysis of single bactrial cells, and questions can be answered which are not accessible to the normally applied integral methods. Thus it is possible to establish distributions of, for instance, elemental concentrations within a bacterial population and of correlations between measured characteristics of a bacterium with its morphology. The mass spectrum of a single bacterial cell comprises information on its intracellular cation contents as well as on the organic matrix. The relation between the sodium and potassium contents can serve as a criterion of the physiological state of a cell and of its viability. The information from the organic matrix can be extracted from the complex spectra of fragment ions produced by the interaction of the laser with the cell by applying multivariate data analysis, thus rendering additional information. Examples will be given for in vitro drug screening and in vivo therapy control in leprosy, an infection which is caused by a mycobacterial species, Mycobacterium leprae; this organism does not multiply in artificial growth media so that only limited numbers of organisms are available for microbiological investigations.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200160191
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