![]() AV-1451 and AV-1451 were characterized in in vitro binding assays using recombinant and native proteins/tissues from postmortem samples of controls and Alzheimer's disease and PSP patients. The aim of the present study was to characterize the in vitro binding of AV-1451 to understand and identify potential off-target binding that could explain the poor discrimination observed in PSP patients. Moreover, accurate quantification of AV-1451 uptake in Alzheimer's disease may not be possible. Although results obtained in Alzheimer's disease patients are compelling, discrimination of tracer uptake in healthy individuals and patients with supranuclear palsy (PSP) is less clear as there is substantial overlap of signal in multiple brain regions. Lilly/Avid's AV-1451 is one of the most advanced tau PET tracers in the clinic. Vermeiren, Céline Motte, Philippe Viot, Delphine Mairet-Coello, Georges Courade, Jean-Philippe Citron, Martin Mercier, Joël Hannestad, Jonas Gillard, Michel The tau positron-emission tomography tracer AV-1451 binds with similar affinities to tau fibrils and monoamine oxidases. However, changes in surface electrostatic interactions sometimes changed the binding specificity of the designed peptides. Incorporating residues that favor helix formation into the designs increased binding affinities in all cases, providing low- nanomolar binders of each target. We have now measured the binding affinities and specificities of anti-bZIPs that bind to FOS, XBP1, ATF6, and CREBZF in solution and tested whether redesigning the surface residues can increase design-target affinity. High-throughput testing using peptide arrays indicated many successes. These "anti-bZIP" peptides were designed with an emphasis on target- binding specificity, with contributions to design-target specificity and affinity engineered considering only the coiled-coil core residues. Here we extend a prior study in which peptides were designed to bind tightly and specifically to representative members of each of 20 human bZIP families. However, folding studies on the model bZIP GCN4 show that coiled-coil surface residues also contribute to binding affinity. Previous work designing peptides to compete with native coiled-coil interactions focused primarily on designing the core residues of the interface to achieve affinity and specificity. This makes coiled coils attractive protein-protein interaction targets to disrupt using engineered molecules. The basic leucine-zipper (bZIP) transcription factors are one family of proteins for which coiled-coil mediated dimerization is essential for function, and misregulation of bZIPs can lead to disease states including cancer. The coiled-coil dimer is a prevalent protein interaction motif that is important for many cellular processes. Kaplan, Jenifer B Reinke, Aaron W Keating, Amy E Increasing the affinity of selective bZIP- binding peptides through surface residue redesign. Hence, high affinity tumor targeting and tunable albumin binding were combined in one small adaptable protein. The new affinity proteins competed for ERBB2- binding with the monoclonal antibody trastuzumab and recognized the native receptor on a human cancer cell line. Moreover, parallel selections against ERBB2 in the presence of human serum albumin identified several amino acid substitutions that dramatically modulate the albumin affinity, which could provide a convenient means to control the pharmacokinetics. Several affinity-matured molecules were shown to bind human ERBB2 with sub- nanomolar affinity while retaining the interaction with human serum albumin. Cell surface display and flow-cytometric sorting allowed stringent selection of top candidates from pools pre-enriched by phage display. Phage display selection against ERBB2 was used for identification of a lead candidate, followed by affinity maturation using second-generation libraries. In an attempt aimed at combining ERBB2-targeting with antibody-like pharmacokinetic properties in a small protein format, we have engineered bispecific ERBB2- binding proteins that are based on a small albumin- binding domain. However, small proteins and peptides generally suffer from fast excretion through the kidneys, and thereby require frequent administration in order to maintain a therapeutic concentration. In such strategies, the full-length antibody format is probably not required for therapeutic effect and smaller tumor-specific affinity proteins might be an alternative. Recent studies suggest that the over-expression of this receptor in various cancers might also be exploited for antibody-based payload delivery, e.g. The epidermal growth factor receptor 2, ERBB2, is a well-validated target for cancer diagnostics and therapy. ![]() Nilvebrant, Johan Åstrand, Mikael Georgieva-Kotseva, Maria Björnmalm, Mattias Löfblom, John Hober, Sophia ![]() Engineering of Bispecific Affinity Proteins with High Affinity for ERBB2 and Adaptable Binding to Albumin ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |