Hybridization of an Aß-specific antibody fragment with aminopyrazole-based ß-sheet ligands displays striking enhancement of target affinity.

Determining Aß levels in body fluids remains a powerful tool in the diagnostics of Alzheimer's disease. This report delineates a new supramolecular strategy which increases the affinity of antibodies towards Aß to make diagnostic procedures more sensitive. A monoclonal antibody IC16 was generated to an N-terminal epitope of Aß and the variable regions of the heavy and light chains were cloned as a recombinant protein (scFv). A 6 × histidine tag was fused to the C-terminus of IC16-scFv allowing hybridization with a small organic ß-sheet binder via Ni-NTA complexation. On the other hand, a multivalent nitrilotriacetic acid (NTA)-equipped trimeric aminopyrazole (AP) derivative was synthesized based on a cyclam platform; and experimental evidence was obtained for efficient Ni(2+)-mediated complex formation with the histidine-tagged antibody species. In a proof of principle experiment the hybrid molecule showed a strong increase in affinity towards Aß. Thus, the specific binding power of recombinant antibody fragments to their ß-sheet rich targets can be conveniently enhanced by non-covalent hybridization with small organic ß-sheet binders.

Synthesis of a hexahydropyrrolo indole (HPI) compound library.

Scaffolds of natural products represent promising starting points for the development of focused compound libraries. Here, we describe the development of a synthetic route to a compound library based on the hexahydropyrrolo indole (HPI) scaffold, the denoting structural motif of the HPI natural product family. To this end, a two-step approach consisting of a batch synthesis of an advanced functionalizable HPI intermediate followed by the establishment of reaction conditions that allow derivatization of this scaffold at three different positions is described. Subsequently, the optimized methods were applied to the synthesis of a 276-member library.