Crystal structure and thermodynamic analysis of diagnostic mAb 106.3 complexed with BNP 5-13 (C10A).
Proteins
; 76(3): 536-47, 2009 Aug 15.
Article
em En
| MEDLINE
| ID: mdl-19274732
ABSTRACT
B-type natriuretic peptide (BNP) is a naturally secreted regulatory hormone that influences blood pressure and vascular water retention in human physiology. The plasma BNP concentration is a clinically recognized biomarker for various cardiovascular diseases. Quantitative detection of BNP can be achieved in immunoassays using the high-affinity monoclonal IgG1 antibody 106.3, which binds an epitope spanning residues 5-13 of the mature bioactive peptide. To understand the structural basis of this molecular recognition, we crystallized the Fab fragment complexed with the peptide epitope and determined the three-dimensional structure by X-ray diffraction to 2.1 A resolution. The structure reveals the detailed interactions that five of the complementarity-determining regions make with the partially folded peptide. Thermodynamic measurements using fluorescence spectroscopy suggest that the interaction is enthalpy driven, with an overall change in free energy of binding, DeltaG = -54 kJ/mol, at room temperature. The parameters are interpreted on the basis of the structural information. The kinetics of binding suggest a diffusion-limited mechanism, whereby the peptide easily adopts a bound conformation upon interaction with the antibody. Moreover, comparative analysis with alanine-scanning results of the epitope explains the basis of selectivity for BNP over other related natriuretic peptides.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Cristalografia por Raios X
/
Peptídeo Natriurético Encefálico
/
Anticorpos Monoclonais
/
Complexo Antígeno-Anticorpo
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Revista:
Proteins
Ano de publicação:
2009
Tipo de documento:
Article