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  • 1
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Escherichia coli iron transport system via ferrichrome belongs to the group of ATP-dependent transporters that are widely distributed in prokaryotes and eukaryotes. Transport across the cytoplasmic membrane is mediated by three proteins: FhuD in the periplasm, FhuB in the cytoplasmic membrane and FhuC (ATPase) associated with the inside of the cytoplasmic membrane. Interaction of FhuD with FhuB was studied in vitro with biotinylated synthetic 10 residue and 20–24 residue peptides of FhuB by determining the activity of β-galactosidase linked to the peptides via streptavidin. Peptides identical in sequence to only one of the four periplasmic loops (loop 2), predicted by a transmembrane model of FhuB, and peptides representing a transmembrane segment and part of the adjacent cytoplasmic loop 7 of FhuB bound to FhuD. Decapeptides were transferred into the periplasm of cells through a FhuA deletion derivative that forms permanently open channels three times as large as the porins in the outer membrane. FhuB peptides that bound to FhuD inhibited ferrichrome transport, while peptides that did not bind to FhuD did not affect transport. These data led us to propose that the periplasmic FhuD interacts with a transmembrane region and the cytoplasmic segment 7 of FhuB. The transmembrane region may be part of a pore through which a portion of FhuD inserts into the cytoplasmic membrane during transport. The cytoplasmic segment 7 of FhuB contains the conserved amino acid sequence EAA…G (in FhuB DTA…G) found in ABC transporters, which is predicted to interact with the cytoplasmic FhuC ATPase. Triggering of ATP hydrolysis by substrate-loaded FhuD may occur by physical interaction between FhuD and FhuC, which bind close to each other on loop 7. Although FhuB consists of two homologous halves, FhuB(N) and FhuB(C), the sites identified for FhuD-mediated ferrichrome transport are asymmetrically arranged.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-3904
    Keywords: alamethicin ; circular dichroism ; ELISA ; hepatitis C ; spacer ; tetraethylene glycol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary New hydrophilic linkers of the formula Fmoc-NHCH2CH2COO(CH2CH2O)4X (X=COCH2CH2COOH Fmoc-Ats (2), X=CONHCH2COOH Fmoc-Atg (4) and X=CONHCH2CH2COOH Fmoc-Ata (5) have been prepared by heterobifunctional modification of tetraethylene glycol as starting material. These linkers represent a useful tool for solid phase peptide synthesis according to Fmoc/tBu strategy. Two examples are presented to illustrate the applicability of these building blocks: (i) spacing between biotin and a peptide epitope of the hepatitis C virus and evaluation in a biotin-streptavidin ELISA, and (ii) coupling of the new linker to the N- and C-terminus of the peptide antibiotic alamethicin to show eventual influences on the peptide's α-helical conformation.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-3904
    Keywords: alamethicin ; circular dichroism ; ELISA ; hepatitis C ; spacer ; tetraethylene glycol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract New hydrophilic linkers of the formula Fmoc- NHCH2CH2COO(CH2CH2O)4X (X = COCH2CH2COOH Fmoc-Ats (2), X = CONHCH2COOH Fmoc-Atg (4), and X = CONHCH2CH2COOH Fmoc-Ata (5)) have been prepared by heterobifunctional modification of tetraethylene glycol as starting material. These linkers represent a useful tool for solid phase peptide synthesis according to Fmoc/tBu strategy. Two examples are presented to illustrate the applicability of these building blocks: (i) spacing between biotin and a peptide epitope of the hepatitis C virus and evaluation in a biotin- streptavidin ELISA, and (ii) coupling of the new linker to the N- and C-terminus of the peptide antibiotic alamethicin to show eventual influences on the peptide's α-helical conformation.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0947-6539
    Keywords: binding assays ; immunosensors ; electrochemical polymerisations ; peptide derivatives ; peptide immobilisation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For the first time, antigenic peptides have been immobilised by electrochemical polymerisation after having been modified with a polymerisable functional group. 3-Hydroxyphenylacetic acid was chosen as the novel polymerisable group. The synthetic peptides represent epitopes of the bovine foot and mouth disease virus and of the sodium channel of the cardiac muscle. The polymerisation was performed by applying a constant anodic potential or by cyclic voltammetry. A combination of these two methods was also employed, that is, cyclic voltammetry with a delay at the anodic vertex potential. No additional free phenolic monomer was required for the polymerisation. The layers formed by the polymerisation were recognised by specific antibodies. The specific binding of the antibodies to the polymer film could be demonstrated by ELISA, an enzyme-linked amperometric immunoassay, and electrochemical impedance measurements, as well as by fluorescence-labelled antibodies. A peptide derived from laminine was also immobilised by electrochemical polymerisation. It could be shown that neuroblastoma cells adhere to this layer.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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