3E8U

Crystal structure and thermodynamic analysis of diagnostic Fab 106.3 complexed with BNP 5-13 (C10A) reveal basis of selective molecular recognition

Summary for 3E8U

• Entry DOI: 10.2210/pdb3e8u/pdb
• Descriptor: Fab 106.3 heavy chain, Fab 106.3 light chain, BNP peptide epitope, ... (4 entities in total)
• Functional Keywords: fab 106.3, igg1, brain natriuretic peptide (bnp), immune system
• Biological source: Mus musculus; More
• Total number of polymer chains: 3
• Total formula weight: 48149.18

Authors

Longenecker, K.L.,Ruan, Q.,Fry, E.H.,Saldana, S.S.,Brophy, S.E.,Richardson, P.L.,Tetin, S.Y. (deposition date: 2008-08-20, release date: 2009-07-07, Last modification date: 2017-10-25)

Primary citation

Longenecker, K.L.,Ruan, Q.,Fry, E.H.,Saldana, S.C.,Brophy, S.E.,Richardson, P.L.,Tetin, S.Y.
Crystal structure and thermodynamic analysis of diagnostic mAb 106.3 complexed with BNP 5-13 (C10A).
Proteins, 76:536-547, 2009

PubMed 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.

PubMed: 19274732
DOI: 10.1002/prot.22366

Experimental method

X-RAY DIFFRACTION (2.1 Å)