Use of conformationally constrained peptides for a topographical analysis of the combing site of a monoclonal anti-substance P antibody.
The topography of the binding site of a monoclonal anti-substance P antibody directed toward the C-terminal pentapeptide of substance P, Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2, was analyzed further using a wide range of constrained analogues of substance P. Results obtained in the present study show the following: (a) The binding subsites of Phe7 and Phe8 are large and deep, accommodating various side chains, including nonaromatic amino acids. (b) In contrast, the binding pockets for Gly-Leu-Met-NH2 appear more restrictive. Consequently, five residues in the peptide are necessary for the high binding affinity to the antibody, the C-terminal tripeptide determining the binding specificity. These data, which appear to contradict those previously published, illustrate the limits of conclusions drawn from studies generally carried out using exclusively Ala-substituted peptides. In addition, the present results indicate that the topography of the binding site of this monoclonal antibody differs from that of the specific substance P neurokinin-1 receptor, in agreement with the differences observed in the fine specificities of these two substance P binding macromolecules.
Déry
O
O
CEA, Service de Pharmacologie et d'immunologie DSV/DRIPP, Bât 136, Gif-sur-Yvette, France.
Josien
H
H
Grassi
J
J
Chassaing
G
G
Couraud
J Y
JY
Lavielle
S
S
D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000276:immunology; D001665:Binding Sites; D001666:Binding Sites, Antibody; D009842:Oligopeptides / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D018040:Receptors, Neurokinin-1 / Q000737:chemistry / Q000378:metabolism; D013373:Substance P / Q000031:analogs & derivatives / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism
D000911:Antibodies, Monoclonal; D009842:Oligopeptides; D018040:Receptors, Neurokinin-1; D013373:Substance P