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  • 1
    Digitale Medien
    Digitale Medien
    Evaluation of errors of interproton distances and correlation time determined from NMR cross-relaxation rates (1992)
    Springer
    Journal of biomolecular NMR 2 (1992), S. 573-582 
    Details
    ISSN: 1573-5001
    Schlagwort(e): Amaninamide ; Correlation time ; Evaluation of errors ; Interproton distances ; NOESY ; ROESY ; 2D NMR ; Peptides ; Cross-relaxation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary We have analyzed a combined use of the two-dimensional nuclear Overhauser effect in the laboratory frame (NOESY) and in the rotating frame (ROESY) to determine interproton distances and correlation time in medium-sized rigid molecules (Davis, 1987). This method can be applied in the intermediate motional regime, 0.2 〈 ωoτc, 〈 5, (τc, correlation time, (ωo resonance frequency). Error limits depend on the motional regime and are smallest near ωoτc=1.14. The method was tested on six geminal proton pairs in the bicyclic octapeptide (S-deoxo-γ-[R]-OH-Ile3 amaninamide, Mw =870) for which at 297 K in DMSO, a correlation time of 1.0 ns, with a standard deviation of 0.12 ns, and an interproton distance of 1.87 Å, with standard deviation of 0.04 Å, are obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02192846
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  • 2
    Digitale Medien
    Digitale Medien
    New synthetic tools for peptide-tetraphenylporphyrin derivatives (1998)
    Springer
    International journal of peptide research and therapeutics 5 (1998), S. 269-276 
    Details
    ISSN: 1573-3904
    Schlagwort(e): metalloenzymes ; peptide-porphyrins ; solid-phase peptide-synthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary New metal-tetraphenylporphyrins and Fmoc-lysine-metalloporphyrin derivatives have been used to prepare peptide-porphyrin and peptide-metalloporphyrin compounds via solid-phase peptide synthesis. A water-soluble peptide, covalently bound to a manganese(III)-porphyrin, has been used as a catalyst to promote the oxidation of ABTS by hydrogen peroxide ort-butylhydroperoxide.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02443544
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  • 3
    Digitale Medien
    Digitale Medien
    New Synthetic Tools for Peptide-Tetraphenylporphyrin Derivatives (1998)
    Springer
    International journal of peptide research and therapeutics 5 (1998), S. 269-276 
    Details
    ISSN: 1573-3904
    Schlagwort(e): metalloenzymes ; peptide-porphyrins ; solid-phase peptide-synthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract New metal-tetraphenylporphyrins and Fmoc-lysine-metalloporphyrin derivatives have been used to prepare peptide-porphyrin and peptide-metalloporphyrin compounds via solid-phase peptide synthesis. A water-soluble peptide, covalently bound to a manganese(III)-porphyrin, has been used as a catalyst to promote the oxidation of ABTS by hydrogen peroxide or t-butylhydroperoxide.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008869818565
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  • 4
    Digitale Medien
    Digitale Medien
    β-Amino acid residues: Conformational characterization of an N- and C-protected homo-β-(S)-leucine (1997)
    Springer
    International journal of peptide research and therapeutics 4 (1997), S. 129-134 
    Details
    ISSN: 1573-3904
    Schlagwort(e): homo-β-Amino acids ; β-Amino acid residue ; X-ray diffraction ; Crystal structure ; Solid-state conformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract An N- and C-protected derivative of homo-β-leucine, Fmoc-homo-β-(S)-leucine methyl ester, synthesized from the corresponding proteinogenic parent α-amino acid in enantiopure form has been fully characterized in the solid state by X-ray diffraction analysis. The crystal conformation of this new residue indicates an extended conformation for this homo-β-residue, with the ϕ torsion angle being more constrained than the µ and ψ angles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008895310236
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  • 5
    Digitale Medien
    Digitale Medien
    β-amino acid residues: Conformational characterization of an N- and C-protectedhomo-β-(S)-leucine (1997)
    Springer
    International journal of peptide research and therapeutics 4 (1997), S. 129-134 
    Details
    ISSN: 1573-3904
    Schlagwort(e): homo-β-Amino acids ; β-Amino acid residue ; X-ray diffraction ; Crystal structure ; Solid-state conformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An N- and C-protected derivative ofhomo-β-leucine, Fmoc-homo-β-(S)-leucine methyl ester, synthesized from the corresponding proteinogenic parent α-amino acid in enantiopure form has been fully characterized in the solid state by X-ray diffraction analysis. The crystal conformation of this new residue indicates and extended conformation for thishomo-β-residue, with the ϕ torsion angle being more constrained than the μ and ψ angles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02443524
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  • 6
    Digitale Medien
    Digitale Medien
    Conformational behaviour of A cyclolinopeptide a analogue: Two-dimensional NMR study of cyclo(Pro1-Pro-Phe-Phe-Ac6c-IIe-ala-Val8) (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 1 (1995), S. 330-340 
    Details
    ISSN: 1075-2617
    Schlagwort(e): Cyclolinopeptide A ; cyclooctapeptides ; NMR ; conformational studies ; restrained molecular dynamics ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The cyclic octapeptide cyclo[-Pro1-Pro-Phe-Phe-Ac6c-Ile-ala-Val8-] [C8-Ac6c], containing the Pro1-Pro-Phe-Phe sequence, followed by a bulky helicogenic Cα,α-dialkylated glycine residue Ac6c (1-aminocyclohexane-1-carboxylic acid), and a D-Ala residue at position 7 has been synthesized. This cyclic peptide is a deletion analogue of the naturally occurring cyclic nonapeptide cyclolinopeptide A (CLA). It has been designed with the aim of studying the role that the Ac6c and D-Ala residues play on the conformational behaviour of the whole molecule and their influence on the conformation of the Pro1-Pro-Phe-Phe sequence when compared with cyclolinopeptide A.C8Ac6c has been investigated in chloroform and acetonitrile solutions by 2D NMR techniques. Only one set of sharp signals is observed in both solvents. This evidence strongly supports the hypothesis that only one conformational state exists in the chosen solvents. The interpretation of the experimental data points to the existence for C8-Ac6c of a very rigid structure stabilized by intramolecular hydrogen bonds. The measured NOE effects allow the calculation of internuclear distances, which have been used as restraints in molecular dynamic calculations. The proposed conformation of the molecule shows that the Pro-Pro-Phe segment retains the conformation observed in natural CLA both in solution and in the solid state and that the Ac6c residue indeed reinforces the ring rigidity not permitting the formation of any appropriate cavity in which inorganic cations could be complexed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/psc.310010508
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  • 7
    Digitale Medien
    Digitale Medien
    Elucidation of the structure of constrained bicyclopeptides in solution by two-dimensional cross-relaxation spectroscopy: Amatoxin analogues (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 3-13 
    Details
    ISSN: 1075-2617
    Schlagwort(e): Structure of amatoxin analogues ; constrained bicyclopeptides ; NMR ; molecular dynamics ; Chemistry ; Biochemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The evaluation of peptide structures in solution is made feasible by the combined use of two-dimensional NMR in the laboratory (NOESY) and rotating frames (ROESY), and by the use of molecular dynamics calculations. The present paper describes how both the NMR method and molecular dynamics calculations were applied to very rigid synthetic bicyclic peptides that are analogues of natural amatoxins. The NMR theory, which allows the estimate of interatomic distances between interacting nuclei, is briefly discussed. The experimental data were compared with those of known solid-state structures. Three amatoxin analogues have been examined. Of these, one is biologically active (S-deoxo γ[R] OH-Ile3-amaninamide) and its structure in the solid state has recently been worked out. The second and third analogues (S-deoxo-Ile3 -Ala5-amaninamide and S-deoxo-D-Ile3 -amaninamide, respectively) are inactive and their solid-state structures are unknown. The data presented confirm the authors' previous hypothesis that lack of biological activity of S-deoxo-Ile3-Ala5- amaninamide is due to the masking of the tryptophan ring by the methyl group of L-Ala and not to massive conformational changes of the analogue.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/psc.44
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  • 8
    Digitale Medien
    Digitale Medien
    Conformational Analysis by NMR and Distance-Geometry Techniques of Deltorphin Analogs (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 2279-2287 
    Details
    ISSN: 1434-193X
    Schlagwort(e): Receptor selectivity ; Agonist activity ; Distance geometry ; Conformation ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: To identify the peptide conformation that is preferentially recognized by the receptor, we have synthetized by solid-phase method a series of deltorphin I analogs with increasing selectivity for δ- and μ-opioid receptor. Structure-selectivity relationship of these peptides were evaluated on the basis of receptor-binding properties and conformational features, computed by two-dimensional NMR spectra and distance-geometry techniques. These compounds in solution are present with a large number of conformers with no defined secondary structural elements. The analysis of the average properties of these compounds indicate the presence of some distinct conformational preferences that can be related to the observed opioid receptor selectivities. Selectivity for the δ- and μ-opioid receptors can be ascribed to the spatial arrangement of the aromatic moieties. In addition, substitutions in position 2 and 4 are important for the correct arrangement and must be taken into account in the design of δ-opioid receptor-selective ligands.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Discovering protein secondary structures: Classification and description of isolated α-turns (1996)
    New York : Wiley-Blackwell
    Biopolymers 38 (1996), S. 705-721 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Irregular protein secondary structures are believed to be important structural domains involved in molecular recognition processes between proteins, in interactions between peptide substrates and receptors, and in protein folding. In these respects tight turns are being studied in detail. They also represent template structures for the design of new molecules such as drugs, pesticides, or antigens. Isolated α-turns, not participating in α-helical structures, have received little attention due to the overwhelming presence of other types of tight turns in peptide and protein structures. The growing number of protein X-ray structures allowed us to undertake a systematic search into the Protein Data Bank of this uncharacterized protein secondary structure. A classification of isolated α-turns into different types, based on conformational similarity, is reported here. A preliminary analysis on the occurrence of some particular amino acids in certain positions of the turned structure is also presented. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Solvent-mediated conformational transition in β-alanine containing cyclic peptides. VIIIprevious parts of this series are in Refs 1-7. (1996)
    New York : Wiley-Blackwell
    Biopolymers 38 (1996), S. 693-703 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In the present paper we describe the solution nmr structural analysis and restrained molecular dynamic simulation of the cyclic pentapeptide cyclo-(Pro-Phe-Phe-β-Ala-β-Ala). The conformational analysis carried out in CD3CN and dimethylsulfoxide (DMSO) solutions by nmr spectroscopy was based on interproton distances derived from rotating frame nuclear Overhauser effect spectroscopy spectra and homonuclear coupling constants. A restrained molecular dynamic simulation in vacuo was also performed to build refined molecular models. The molecule is present in both solvent systems as two slowly interconverting conformers, characterized by a cis-trans isomerism around the β-Ala5-Pro1 peptide bond. In CD3CN solution, the conformer with a cis peptide bond is quite similar to that observed in the solid state, while the conformer containing all trans peptide bonds is characterized by an intramolecular hydrogen bond stabilizing a C10- and a C13-ring structure. In DMSO solution, the trans isomer is partly similar to that observed in CD3CN solution while the cis isomer is different from that observed in the solid state. The effect of the solvent in stabilizing different conformations was also investigated in DMSO-CD3CN solvent mixtures. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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