Design, synthesis, and conformational study of biologically active photolabeled analogues of the main immunogenic region of the acetylcholine receptor.
Photoaffinity labeling is a powerful tool for the characterization of the molecular basis of ligand binding to acceptor molecules, which provides important insights for mapping the bimolecular interfaces. The autoimmune disease myasthenia gravis is caused by autoantibodies against the acetylcholine receptor (AChR). The majority of the anti-AChR antibodies bind to the "main immunogenic region" (MIR) of the AChR. To identify the contact points between the complementarity determining regions of the anti-MIR antibodies that recognize the MIR contact sites of the AChR, we present here three photoreactive dodecapeptide MIR analogues containing the photolabel p-benzoyl-L-phenylalanine (Bpa) moiety, either in position 1 or 11. The structure of the produced 12-mers was analyzed using two-dimensional (1)H-NMR spectroscopy, whereas their binding to anti-MIR monoclonal antibodies (mAbs) was determined by immunochemical assays. In all cases the modifications resulted in conservation of the beta-turn conformation of the N-terminus, which has been proved essential for antibody recognition and increased anti-MIR binding relative to the MIR decapeptide.
Theodorou
V
V
Department of Chemistry, University of Ioannina, 45 110 Ioannina, Greece.
Tsikaris
V
V
Sakarellos-Daitsiotis
M
M
Avramopoulou
V
V
Kostelidou
K
K
Tzartos
S J
SJ
Sakarellos
C
C
D000345:Affinity Labels / Q000138:chemical synthesis / Q000737:chemistry*; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001665:Binding Sites; D015195:Drug Design; D006801:Humans; D007120:Immunochemistry; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000276:immunology; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology; D010777:Photochemistry; D011487:Protein Conformation; D011978:Receptors, Nicotinic / Q000737:chemistry* / Q000276:immunology
D000345:Affinity Labels; D000911:Antibodies, Monoclonal; D009842:Oligopeptides; D010446:Peptide Fragments; D011978:Receptors, Nicotinic