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  • 1
    ISSN: 1600-065X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Summary: The neuromuscular junction nicotinic acetylcholine receptor (AChR), a pentameric membrane glycoprotein, is the autoantigen involved in the autoimmune disease myasthenia gravis (MG). In animals immunized with intact AChR and in human MG, the anti-AChR antibody response is polyclonal. However, a small extracellular region of the AChR a-subunit, the main immunogenic region (MIR), seems to be a major target for anti-AChR antibodies. A major loop containing overlapping epitopes for several anti-MIR monoclonal antibodies (mAbs) lies within residues α67–76 at the extreme synaptic end of each a-subunit; however, anti-MIR mAbs are functionally and structurally quite heterogeneous. Anti-MIR mAbs do not affect channel gating, but are very effective in the passive transfer of MG to animals; in contrast, their Fab or Fv fragments protect the AChR from the pathogenic effects of the intact antibodies. Antibodies against the cytoplas-mic region of the AChR can be elicited by immunization with denatured AChR and the precise epitopes of many such mAbs have been identified; however, it is unlikely that such antibodies are present in significant amounts in human MG. Antibodies to other extracellular epitopes on all AChR subunits are present in both experimental and human MG; these include antibodies to the acetylcholine-binding site which affect AChR function in various ways and also induce acute experimental MG. Finally, anti-AChR antibodies cross-reactive with noti-AChR antigens exist, suggesting that MG may result from molecular mimicry. Despite extensive studies, many gaps remain in our understanding of the antigenic structure of the AChR, especially in relation to human MG. A thorough understanding of the antigenic structure of the AChR is required for an in-depth understanding, and for possible specific immunotherapy, of MG.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1573-3904
    Schlagwort(e): Antigen-antibody interaction ; Antigenic peptide ; Leishmania ; SRYD motif ; 2D NMR
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The I250ASRYDQL257 synthetic octapeptideof the Leishmania major surface glycoproteingp63, which efficiently inhibits parasite attachmentto the macrophage receptors and mimics antigenicallyand functionally the RGDS sequence of fibronectin, wasstudied by 2D TR-NOESY in the presence of an anti-SRYDmonoclonal antibody (mAbSRYD) that recognizes bothSRYD-containing peptides and the cognate protein onintact parasites. Molecular modeling was performedusing distance constraints obtained from TR-NOEs. Thebound structure was compared with that of the freepeptide in DMSO solution and with the crystalstructure of the RYD fragment of the OPG2 Fab, anantireceptor antibody that mimics an RGD cell adhesion site.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1573-3904
    Schlagwort(e): Arginine ionic interactions ; gp63 adhesion site ; Arginine-aspartic acid interactions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The antigenicity and conformational properties of the Ser-Arg-Tyr-Asp (SRYD) segment (252–255) of the major surface glycoprotein ofLeishmania, gp63, which plays a key role in the parasite-macrophage attachement, are presented. It was found that the antibody recognition, using anti-IASRYDQL antibodies, of the SRYD-containing analogues, Ac-SRYD-NH2 (1), ANIASRYD-NH2 (2), Ac-SRYD (3), SRYD (4) and ANIASRYD (5), is rather similar. The structure of the SRYD moiety in analogues 1 and 2 is characterized by the presence of a type I β-turn, stabilized by the formation of a hydrogen bonding between the C-terminaltrans-carboxamide proton and the Arg-CO and an ionic bridge between arginine and aspartic acid side chains, while the conformation of compounds 3, 4 and 5 is stabilized by an ionic bridge between the arginine side chain and the C-terminal carboxylate group. A common structural motif involving the arginine side chain in an ionic interaction is identified in all the SRYD analogues, which may explain the observed similarities in the antibody recognition of the reported peptides.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1573-3904
    Schlagwort(e): Antigenicity of the Sm epitope ; Carriers of antigenic peptides ; Peptide conformation ; Proline-rich Sm epitope ; Sm autoantigen ; Systemic lupus erythematosus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The PPGMRPP sequence, found in several copies in the Sm and U1RNPautoantigens, is the main target of anti-Sm and anti-U1RNP antibodies insystemic lupus erythematosus (SLE) and mixed connective tissue disease(MCTD) patient's sera. It is also recognized, to a lower extent, byanti-Ro/SSA and anti-La/SSB specificities. The PPGMRPP-NH2peptide amide and the PPGMRPP peptide, which is bound to a pentamericsequential oligopeptide carrier (SOC5), were examined by1H-NMR spectroscopy and ELISA assays, using sera from patientswith autoimmune rheumatic diseases. Among the three main conformers foundfor the free PPGMRPP, the extended one was also identified for PPGMRPP-NH2 and (PPGMRPP)5-SOC5.This can be attributed to the absence of ionic interactions between theArg-guanidinium and the carboxylate group in the amide andSOC5-bound forms of the peptide. Immunoassays using sera fromvarious specificities showed an enhanced anti-Sm and anti-U1RNP recognitionof PPGMRPP-NH2 and(PPGMRPP)5-SOC5, and lowering of the anti-Ro/SSAand anti-La/SSB reactivity. The presence of multiple conformers of freePPGMRPP may explain the unexpected cross-reactivity to the anti-Ro/Lapositive sera, while the prevalence of the extended conformation inPPGMRPP-NH2 and (PPGMRPP)5-SOC5is mainly responsible for the enhanced recognition from the anti-Sm andanti-U1RNP autoantibodies. It is concluded that the antigenic specificity ofPPGMRPP-NH2 and (PPGMRPP)5-SOC5 ismainly induced by conformational changes resulting from the conversion ofthe C-terminal carboxylate group to the amide form.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    International journal of peptide research and therapeutics 4 (1997), S. 481-487 
    ISSN: 1573-3904
    Schlagwort(e): Catalytic triad residues ; Cyclic branched peptide ; Cyclization on solid support ; Enzymatic properties of serine protease model ; Proline cyclic hexapeptide ; Serine protease model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The design, synthesis and catalytic properties of a cyclic branched peptide carrier that possesses the catalytic triad residues of the serine proteases is reported. The synthesis of the peptide model was totally completed on solid support using three different orthogonal amino protecting groups. Hydrolytic activity measurements against Suc-Ala-Ala-Ala-pNA substrate showed that it is hydrolysed by the peptide model to a small extent. Despite this small hydrolytic activity, it is the first time, to our knowledge, that hydrolysis of such a substrate is reported by an enzyme model compound. Contrary, this enzyme model peptide showed considerable activity against the Boc-Ala-pNP substrate (k cat =0.414 min−1 andK m =0.228 mm). These results suggest that the designed carrier brings in appropriate contact the catalytic triad residues (Ser, His, Asp) resulting in the obtained hydrolytic activity.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1573-3904
    Schlagwort(e): Antigenicity of the Sm epitope ; Carriers of antigenic peptides ; Peptide conformation ; Proline-rich Sm epitope ; Sm autoantigen ; Systemic lupus erythematosus (SLE)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The PPGMRPP sequence, found in several copies in the Sm and U1RNP autoantigens, is the main target of anti-Sm and anti-U1RNP antibodies in systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD) patient's sera. It is also recognized, to a lower extent, by anti-Ro/SSA and anti-La/SSB specificities. The PPGMRPP-NH2 peptide amide and the PPGMRPP peptide, which is bound to a pentameric sequential oligopeptide carrier (SOC5), were examined by1H-NMR spectroscopy and ELISA assays, using sera from patients with autimmune rheumatic diseases. Among the three main conformers found for the free PPGMRPP, the extended one was also identified for PPGMRPP-NH2 and (PPGMRPP)5-SOC5. This can be attributed to the absence of ionic interactions between the Arg-guanidinium and the carboxylate group in the amide and SOC5-bound forms of the peptide. Immunoassays using sera from various specificities showed an enhanced anti-Sm and anti-U1RNP recognition of PPGMRPP-NH2 and (PPGMRPP)5-SOC5, and lowering of the anti-Ro/SSA and anti-La/SSB reactivity. The presence of multiple conformers of free PPGMRPP may explain the unexpected cross-reactivity to the anti-Ro/La positive sera, while the prevalence of the extended conformation in PPGMRPP-NH2 and (PPGMRPP)5-SOC5 is mainly responsible for the enhanced recognition from the anti-Sm and anti-U1RNP autoantibodies. it is concluded that the antigenic specificity of PPGMRPP-NH2 and (PPGMRPP)5-SOC5 is mainly induced by conformational changes resulting from the conversion of the C-terminal carboxylate group to the amide form.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1573-3904
    Schlagwort(e): Antigen-antibody interaction ; Antigenic peptide ; Leishmania pg63 ; Molecular dynamics ; SRYD motif ; 2D NMR
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The I250 ASRYDQL257 synthetic octapeptide of theLeishmania major surface glycoprotein gp63, which efficiently inhibits parasite attachment to the macrophage receptors and mimics antigenically and functionally the RGDS sequence of fibronectin, was studied by 2D TR-NOESY in the presence of an anti-SRYD monoclonal antibody (mAbSRYD) that recognizes both SRYD-containing peptides and the cognate protein on intact parasites. Molecular modeling was performed using distance constraints obtained from TR-NOEs. The bound structure was compared with that of the free peptide in DMSO solution and with the crystal structure of the RYD fragment of the OPG2 Fab, an antireceptor antibody that mimics an RGD cell adhesion site.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    ISSN: 1573-3904
    Schlagwort(e): Leishmania gp63 ; 2D NMR ; Molecular dynamics ; DMSO solvent box ; Arginine ionic bridge ; βI-turn
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The IASRYDQL synthetic octapeptide (250–257) of the Leishmania major surface glycoprotein gp63 efficiently inhibits parasite attachment to the macrophage receptors in in vitro experiments, and the SRYD-containing tetrapeptide mimics antigenically and functionally the RGDS sequence of fibronectin. The conformational properties of the octapeptide were investigated in dimethylsulfoxide (DMSO) with the combined use of NMR data (vicinal coupling constants, nuclear Overhauser effects (NOEs) and temperature coefficient values), molecular modeling by energy minimization and molecular dynamics. The structure is characterized by the high occurrence, exceeding 95%, of the Arg-Asp side-chain-side-chain ionic interaction, which plays a key role in the backbone folding through a distorted type-I β-turn involving the Gln256-NH to Arg253-CO hydrogen bond.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    International journal of peptide research and therapeutics 4 (1997), S. 481-487 
    ISSN: 1573-3904
    Schlagwort(e): Catalytic triad residues ; Cyclic branched peptide ; Cyclization on solid support ; Enzymatic properties of serine protease model ; Proline cyclic hexapeptide ; Serine protease model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The design, synthesis and catalytic properties of acyclic branched peptide carrier that possesses thecatalytic triad residues of the serine proteases isreported. The synthesis of the peptide model wastotally completed on solid support using threedifferent orthogonal amino protecting groups.Hydrolytic activity measurements againstSuc-Ala-Ala-Ala-pNA substrate showed that it ishydrolysed by the peptide model to a small extent.Despite this small hydrolytic activity, it is thefirst time, to our knowledge, that hydrolysis of such a substrate is reported by an enzyme model compound.Contrary, this enzyme model peptide showedconsiderable activity against the Boc-Ala-pNPsubstrate (kcat = 0.414 min–1 and Km = 0.228 mm). These results suggest that thedesigned carrier brings in appropriate contact thecatalytic triad residues (Ser, His, Asp) resulting inthe obtained hydrolytic activity.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The conformational properties of two [D-A70, A76] and [Aib70, A76] analogues of the α67-76 Torpedo acetylcholine receptor fragment, with low binding capacity for the anti main immunogenic region (MIR) antibodies, were studied in DMSO by two-dimensional nmr techniques and molecular dynamics simulations. The results were compared to the free and bound conformations of the [A76] analogue, which has twice more affinity for the anti-MIR monoclonal antibody 6 (mAb6), than the natural Torpedo sequence. It appeared that a single substitution of the A70, at a crucial position, by the D-A70 or Aib70, could modify completely the conformational behavior of the peptide and reduced its recognition by the anti-MIR antibody. The WNPADY rigid structure at the N-terminal part was essential for antibody recognition. The adjacent more flexible C-terminal sequence (GGIK) gives additional stability to the monoclonal antibody-peptide complex probably due to an adequate orientation of the peptide side chains in the complex, by setting them in close contact with the antibody. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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