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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    International journal of peptide research and therapeutics 1 (1994), S. 149-155 
    ISSN: 1573-3904
    Keywords: Solid-phase peptide synthesis ; Side reaction ; Mass spectrometry ; Fmoc-Trp(Boc)-OH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several side reactions can be encountered in the synthesis of Trp-containing peptides, due to molecular species originating from side chain-protecting groups or from the linker during acidolytic cleavage of the peptide from the resin. The linker can be the source of both alkylation in solution of the indole moiety of the tryptophan side chain and permanent readdition of the cleaved peptide to the resin. We report that both these reactions occur at a high level during the synthesis of Trp-containing peptides on a PEG-PS resin containing a 2-methoxybenzyl alcohol-based linker, in spite of the presence of suitable scavengers in the TFA-based cleavage mixture. Both side reactions are efficiently prevented by the use of a protected analogue of tryptophan, namely Nim-Boc-Trp, previously reported for the synthesis of peptides containing tryptophan and arginine residues.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International journal of peptide research and therapeutics 2 (1996), S. 319-323 
    ISSN: 1573-3904
    Keywords: Difficult sequence ; Diketopiperazine ; Solid-phase peptide synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes the synthesis of the bradykinin B1 antagonist [desArg10]HOE 140 (d-Arg-Arg-Pro-Hyp-Gly-Thi-Ser-d-Tic-Oic-OH) by the solid-phase method. This synthesis is predicted to be a difficult one because the C-terminal sequence d-Tic-Oic, when linked to the resin, could easily undergo an intramolecular aminolysis, releasing the corresponding diketopiperazine. This reaction is greatly favored by the imino acidic structure of these two residues and by the d-configuration of the second one. When using the Fmoc strategy, the reaction takes place during the Fmoc removal with piperidine. In this case, it has been suggested previously that it is possible to prevent the side reaction by reducing the time of the base treatment. In our hands, this expedient worked correctly for the synthesis of a test tetrapeptide (H-Gly-Pro3-OH), but under the same conditions the synthesis of the target peptide failed completely. In contrast, the use of the very hindered 2-chlorotrityl resin reduced diketopiperazine formation to undetectable levels.
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  • 3
    ISSN: 1573-3904
    Keywords: B1 kinin receptor ; peptide antagonist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract It has recently been shown that the biological activity of the second generation kinin B1 receptor selective antagonist, desArg10 HOE 140, can be improved by specific amino acid substitutions. Starting from this observation, we undertook a systematic structure-activity relationship study of this antagonist, based on the alanine-scan technique, in order to obtain useful information for the rational design of more analogues. Our data indicate that the sequence of desArg10 HOE 140 does not tolerate the replacement by Ala of most of its residues, with the exception of Ser in position 7 and, to a lesser extent, D-Arg in position 1 and Hyp in position 4. The most critical residues appear to be Pro in position 3 and the C-terminal dipeptide DTic-Oic; Ala replacement at these positions resultes in a total loss of activity. Moreover, replacement by Ala of Gly in position 5 reverts the activity of desArg10 HOE 140 to that of an agonist.
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  • 4
    ISSN: 1573-3904
    Keywords: B1 kinin receptor ; peptide antagonist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It has recently been shown that the biological activity of the second generation kinin B1 receptor selective antagonist, desArg10 HOE 140, can be improved by specific amino acid substitutions. Starting from this observation, we undertook a systematic structure-activity relationship study of this antagonist, based on the alanine-scan technique, in order to obtain useful information for the rational design of more analogues. Our data indicate that the sequence of desArg10 HOE 140 does not tolerate the replacement by Ala of most of its residues, with the exception of Ser in position 7 and, to a lesser extent, D-Arg in position 1 and Hyp in position 4. The most critical residues appear to be Pro in position 3 and the C-terminal dipeptide Dtic-Oic; Ala replacement at these positions resultes in a total loss of activity. Moreover, replacement by Ala of Gly in position 5 reverts the activity of desArg10 HOE 140 to that of an agonist.
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  • 5
    ISSN: 1573-3904
    Keywords: Azobenzene ; Dimerization ; Photoisomerization ; Proteinase inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The synthesis and biological activity of a photochromic compound, in which two Lys2 dipeptides are linked through their N-terminal amino groups by an azobenzene moiety, are reported. The synthesis was achieved by a novel solid-phase dimerization strategy, based on the reaction of 4,4′-azobenzene dibenzoyl chloride with two N-terminal amino groups of distinct Lys2 dipeptides directly on the resin. Both the trans form and the photostationary state mixture (59% cis and 41% trans) inhibit a plant proteinase which is known to be sensitive to polycationic compounds.
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  • 6
    ISSN: 1075-2617
    Keywords: Antagonists ; chemometry ; major histocompatibility complex ; molecular modelling ; unnatural amino acids ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A direct binding assay has been used to investigate the effect of the secondary anchor residues on peptide binding to class I proteins of the major histocompatibility complex. Based on predictions from a previous chemometric approach, synthetic peptide analogues containing unnatural amino acids were synthesized and tested for B*2705 binding. Hydrophobic unnatural amino acids such as α-naphthyl- and cyclohexyl-alanine were found to be excellent substituents in the P3 secondary anchor position giving peptides with very high B*2705-binding affinity. The binding to B*2705 of peptides optimized for their secondary anchor residues, but lacking one of the P2 or P9 primary anchor residues was also investigated. Most such peptides did not bind, but one peptide, lacking the P2 Arg residue generally considered essential for binding to all B27 subtypes, was found to bind quite strongly. These findings demonstrate that peptide binding to class I proteins is due to a combination of all the anchor residues, which may be occupied also by unnatural amino acids-a necessary step towards the development of peptidic or non-peptidic antagonists for immunomodulation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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