Two‐Dimensional ¹H‐nmr study of antigen–antibody interactions: Binding of synthetic decapeptides to an anti‐acetylcholine receptor monoclonal antibody

Abstract

Two-dimensional NMR experiments [correlated spectroscopy (COSY) and two-dimensional transferred nuclear Overhauser enhancement spectroscopy (TR-NOESY)] have been applied to study the interactions of a monoclonal antibody (mAb) directed to the main immunogenic region (MIR) of the acetylcholine receptor (AChR), and four synthetic decapeptides from the MIR. The decapeptides were the Torpedo AChR alpha 67-76 fragment (W67-N68-P69-A70-D71-Y72-G73-+ ++G74-I75-K76) and its three [A69], [A73], and [A76] analogues. The results led to the following conclusions: (1) the magnitude of the TR-NOE cross peaks does not depend only on the structuration of the peptide in the bound state, but also on restrictions of the mobility, i.e., on the correlation time tau c, which can be different for every residue; (2) the binding capacity of the synthetic peptides to mAbs measured by radioimmunoassay is directly correlated to the NOE magnitude; and (3) the combined interpretation of the COSY and TR-NOESY experiments gives a qualitative information about the nature and the overall conformation of the sequence which is in contact with the mAb binding site.

Bacterial expression of a single‐chain Fv fragment which efficiently protects the acetylcholine receptor against antigenic modulation caused by myasthenic antibodies

“…Furthermore, these regions are very hydrophobic as was deduced by computer analysis (data not shown). These characteristics correlate well with the conformational analysis of the MIR [lo, 11,47,481.The N-terminal half of the a67-76 (MIR) decapeptide (i.e. a67-71) contains the most critical residues for antibody binding [S] and is by itself capable of binding to the mAbs [47].…”

The Nuclear Overhauser Effect in the Lead Identification Process Pharmacophore Models

“…Since then, the tr-NOE technique has been used to analyze the conformational properties of several peptides bound to proteins and antibodies [55][56][57][58][59][60][61][62]. Works related to complexes between sugar and proteins [63,64] or sugar and antibodies [65] have also been performed.…”

Compared structures of the free nicotinic acetylcholine receptor main immunogenic region (MIR) decapeptide and the antibody-bound [A76] MIR analogue: A molecular dynamics simulation from two-dimensional NMR data

“…The radial distribution functions for all intermolecular atom pairs calculated from the atomic trajectories during the last 40 ps of MD are in agreement with both Rao and Singh simulationsz8 and the x-ray structure of DMS0.29 A DGII calculation was performed on the extended MIR peptide with a set of 19 backbone-backbone, 20 backbone-side-chain, and 7 side-chain-side-chain distance constraints. Due to the multiple orientation of the side chains denoted by the JmSP coupling constants, 19," the backbone-side-chain and side-chain-side-chain distance constraints were associated with a lower force constant (4 kcal mol-' k') than the backbone-backbone distance constraints (12 kcal mol-' k*). The nonassigned prochiral protons in the side chains were replaced by pseudoatoms.…”