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  • 1
    ISSN: 0170-2041
    Keywords: Lantibiotics ; Circular dichroism ; Gallidermin ; Percursor proteins ; Conformation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to investigate the conformational properties of the precursor proteins of lanthionine-containing bacteriocins we synthesized the leader peptides of the pre-lantibiotics of gallidermin, epidermin, Pep5, nisin, subtilin, the C-terminal 30-mer segment of pre-cinnamycin, propeptide segments of Pep5 and gallidermin and the complete pre-gallidermin, which consists of 52 residues. The peptides were synthesized in a step-by-step synthesis by the Fmoc/tBu strategy using an optimized procedure for the synthesis of large peptides. All peptides were analyzed by HPLC and characterized by electrospray mass spectrometry and amino acid analysis. Circular dichroism spectra exhibited strong α-helical Cotton effects even at a low concentration of trifluoroethanol for all N-terminal leader peptides. Comparative investigations of the C-terminal propeptide segments led to a model of the conformation of the prepeptides of Pep5 and gallidermin in aqueous and lipophilic environments. In addition, circular dichroism investigations on the synthetic precursor protein of gallidermin and the isolated natural pre-Pep5 were performed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0170-2041
    Keywords: Cyclization methods ; Neuropeptide Y ; Coupling reagents ; Cyclopeptide ; Peptide synthesis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The short-cut analog of neuropeptide Y (NPY), NPY 1YESK-Ahx-25RHYINKITRQRY-NH2, was synthesized on the amide anchor 5-(4-aminomethyl-3,5-dimethoxyphenoxy)valeric acid (ADPV) attached to polystyrene/1% divinylbenzene by using the 9-fluorenylmethoxycarbonyl/tert-butyl (Fmoc/tBu) strategy. Side-chain-to-side-chain cyclization of residues Glu2 to Lys30 of this linear heptadecapeptide amide was carried out by using different activating reagents under high-dilution conditions of the free peptide. The use of diphenylphosphoryl azide (DPPA) with the addition of triethylamine gave the highest yield of cyclic peptide. Replacing the tertiary amine by dipotassium hydrogen phosphate as an insoluble inorganic base did not improve the cyclization. Complete cyclization was achieved within four hours by using 2-(1H-benzotriazol-1-yl) -1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU) in combination with 1-hydroxybenzotriazol (HOBt) as activating agent, but the separation from excess TBTU resulted in lower yields. Reactions were monitored by HPLC and kinetic investigations were made. The identity and purity of the final product were proven by various analytical methods including atmospheric pressure ionization mass spectrometry (API-MS). The receptor binding constant of the cyclic analog was found to be comparable to that of NPY.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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