Solution-Based Determination of Dissociation Constants for the Binding of Aß42 to Antibodies.

ABSTRACT

Amyloid ß-peptides (Aß) play a major role in the pathogenesis of Alzheimer's disease. Therefore, numerous monoclonal antibodies against Aß have been developed for basic and clinical research. The present study applied fluorescence based analytical ultracentrifugation and microscale thermophoresis to characterize the interaction between Aß42 monomers and three popular, commercially available antibodies, namely 6E10, 4G8 and 12F4. Both methods allowed us to analyze the interactions at low nanomolar concentrations of analytes close to their dissociation constants (K D) as required for the study of high affinity interactions. Furthermore, the low concentrations minimized the unwanted self-aggregation of Aß. Our study demonstrates that all three antibodies bind to Aß42 monomers with comparable affinities in the low nanomolar range. K D values for Aß42 binding to 6E10 and 4G8 are in good agreement with formerly reported values from SPR studies, while the K D for 12F4 binding to Aß42 monomer is reported for the first time.