2HKF

Crystal structure of the Complex Fab M75- Peptide


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.01 Å
  • R-Value Free: 0.242 
  • R-Value Work: 0.176 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Stabilization of antibody structure upon association to a human carbonic anhydrase IX epitope studied by X-ray crystallography, microcalorimetry, and molecular dynamics simulations.

Kral, V.Mader, P.Collard, R.Fabry, M.Horejsi, M.Rezacova, P.Kozisek, M.Zavada, J.Sedlacek, J.Rulisek, L.Brynda, J.

(2008) Proteins 71: 1275-1287

  • DOI: 10.1002/prot.21821
  • Primary Citation of Related Structures:  2HKH

  • PubMed Abstract: 
  • Specific antibodies interfere with the function of human tumor-associated carbonic anhydrase IX (CA IX), and show potential as tools for anticancer interventions. In this work, a correlation between structural elements and thermodynamic parameters of ...

    Specific antibodies interfere with the function of human tumor-associated carbonic anhydrase IX (CA IX), and show potential as tools for anticancer interventions. In this work, a correlation between structural elements and thermodynamic parameters of the association of antibody fragment Fab M75 to a peptide corresponding to its epitope in the proteoglycan-like domain of CA IX, is presented. Comparisons of the crystal structures of free Fab M75 and its complex with the epitope peptide reveal major readjustments of CDR-H1 and CDR-H3. In contrast, the overall conformations and positions of CDR-H2 and CDR-L2 remain unaltered, and their positively charged residues may thus present a fixed frame for epitope recognition. Adoption of the altered CDR-H3 conformation in the structure of the complex is accompanied by an apparent local stabilization. Analysis of domain mobility with translation-libration-screw (TLS) method shows that librations of the entire heavy chain variable domain (V(H)) decrease and reorient in the complex, which correlates well with participation of the heavy chain in ligand binding. Isothermal titration microcalorimetry (ITC) experiments revealed a highly unfavorable entropy term, which can be attributed mainly to the decrease in the degrees of freedom of the system, the loss of conformational freedom of peptide and partially to a local stabilization of CDR-H3. Moreover, it was observed that one proton is transferred from the environment to the protein-ligand complex upon binding. Molecular dynamics simulations followed by molecular mechanics/generalized Born surface area (MM-GBSA) calculations of the ligand (epitope peptide) binding energy yielded energy values that were in agreement with the ITC measurements and indicated that the charged residues play crucial role in the epitope binding. Theoretical arguments presented in this work indicate that two adjacent arginine residues (ArgH50 and ArgH52) are responsible for the observed proton transfer.


    Organizational Affiliation

    Department of Recombinant Expression and Structural Biology, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, 166 37 Prague, Czech Republic.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Immunoglobulin Light chain Fab fragment
L
219N/AN/A
Protein Feature View is not available: No corresponding UniProt sequence found.
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Immunoglobulin Heavy chain Fab fragment
H
218N/AN/A
Protein Feature View is not available: No corresponding UniProt sequence found.
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
Carbonic anhydrase 9
P
9Homo sapiensGene Names: CA9 (G250, MN)
EC: 4.2.1.1
Find proteins for Q16790 (Homo sapiens)
Go to Gene View: CA9
Go to UniProtKB:  Q16790
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.01 Å
  • R-Value Free: 0.242 
  • R-Value Work: 0.176 
  • Space Group: P 1
Unit Cell:
Length (Å)Angle (°)
a = 40.388α = 85.03
b = 43.145β = 88.47
c = 58.023γ = 85.67
Software Package:
Software NamePurpose
MOSFLMdata reduction
REFMACrefinement
SCALAdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-11-13
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Advisory, Version format compliance