Self-association studies on the EphB2 receptor SAM domain using analytical ultracentrifugation.
The self-association behavior of the Eph-kinases SAM domain has been studied in phosphate buffer, pH 7.4, containing 0.14 M NaCl using concentration-dependent sedimentation equilibrium experiments. Only weak interactions typical for a monomer-dimer equilibrium up to at least 12 mg/mL were observed. Such concentrated solutions require a consideration of the non-ideality expressed by virial coefficients. A special centrifuge equation was used for the global analysis to estimate equilibrium constants based on the thermodynamic activities of the reactants. When neglecting this, the parameters deviate by about 20%. Association constants for dimerization of the EphB2-SAM domain vary between 163 M(-1) at 10 degrees C and 395 M(-1) at 32 degrees C, indicating hydrophobic forces are involved in the dimerization process. In solutions of about 12 mg/mL, less than 50% dimers are in solution and higher oligomers can be excluded.
Behlke
J
J
Max Delbrück Center for Molecular Medicine, Berlin, Germany. behlke@mdc-berlin.de
Labudde
D
D
Ristau
O
O
D020816:Amino Acid Motifs; D055592:Biophysical Phenomena; D001703:Biophysics; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D015233:Models, Statistical; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry*; D036183:Receptor, EphB2; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature; D013816:Thermodynamics; D014461:Ultracentrifugation / Q000379:methods*
D012965:Sodium Chloride; D020794:Receptor Protein-Tyrosine Kinases; D036183:Receptor, EphB2