Crystal structure and thermodynamic analysis of diagnostic mAb 106.3 complexed with BNP 5-13 (C10A)

Journal Article · Thu Sep 02 04:00:00 EDT 2010 · Proteins

DOI:https://doi.org/10.1002/prot.22366· OSTI ID:1006141

Longenecker, Kenton L; Ruan, Qiaoqiao; Fry, Elizabeth H; Saldana, Sylvia C; Brophy, Susan E; Richardson, Paul L; Tetin, Sergey Y

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 {angstrom} 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, {Delta}G = -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.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: USDOE
• OSTI ID: 1006141
• Journal Information: Proteins, Journal Name: Proteins Journal Issue: (3) ; 08, 2009 Vol. 76; ISSN PSFGEY; ISSN 0887-3585
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
BLOOD PRESSURE
CARDIOVASCULAR DISEASES
CRYSTAL STRUCTURE
DETECTION
ENTHALPY
FLUORESCENCE SPECTROSCOPY
FREE ENERGY
HORMONES
KINETICS
PEPTIDES
PHYSIOLOGY
PLASMA
RESIDUES
RESOLUTION
RETENTION
THERMODYNAMICS
WATER
X-RAY DIFFRACTION