Immobilization of homogeneous monomeric, oligomeric and fibrillar Aß species for reliable SPR measurements.

ABSTRACT

There is strong evidence that the amyloid-beta peptide (Aß) plays a central role in the pathogenesis of Alzheimer's disease (AD). In this context, a detailed quantitative description of the interactions with different Aß species is essential for characterization of physiological and artificial ligands. However, the high aggregation propensity of Aß in concert with its susceptibility to structural changes due to even slight changes in solution conditions has impeded surface plasmon resonance (SPR) studies with homogeneous Aß conformer species. Here, we have adapted the experimental procedures to state-of-the-art techniques and established novel approaches to reliably overcome the aforementioned challenges. We show that the application of density gradient centrifugation (DGC) for sample purification and the use of a single chain variable fragment (scFv) of a monoclonal antibody directed against the amino-terminus of Aß allows reliable SPR measurements and quality control of the immobilized Aß aggregate species at any step throughout the experiment.