Novel High-affinity Aβ-binding Peptides Identified by an Advanced In Vitro Evolution, Progressive Library Method

Sachika      Tsuji-Ueno; Masayuki      Komatsu; Kakeru      Iguchi; Masahiro      Takahashi; Syuhei      Yoshino; Miho      Suzuki; Naoto      Nemoto; Koichi      Nishigaki

Abstract

Recent studies have been supporting that the generation of Aβ42 oligomers is responsible for Alzheimers disease. Therefore, those peptides which bind to Aβ42 are scientifically interesting and can be possible candidates for the diagnosis and therapy of Alzheimers disease. A systemic in vitro evolution, developed recently and the designated progressive library method (PLM), was applied to obtain Aβ42-binding aptamers peptides. As a result, high affinity peptide aptamers made of 8 or 9 amino acids could be identified by this approach, endorsing the methodological effectiveness. Namely, the selection products from the secondary library of diversified peptides, which was constructed based on the information obtained from the primary library selection, were confirmed to be superior to those selected from the primary library as had been reported previously. The affinities of those peptides measured by SPR (surface plasmon resonance) were comparable to or higher than that of those peptides so far reported (Kd of 10-7). The other peptides selected were confirmed of their binding by a novel mode of gel shift assay (fluorescence enhancement caused by the binding). Thus, novel Aβ42-binding peptides with high affinity were provided for the future Alzheimers disease study. The demonstration of the effectiveness of the systemic in vitro evolution of PLM is very encouraging for the study of identifying novel functional peptides.

Keywords: Alzheimer's disease, amyloid β, cDNA display, in vitro evolution, peptide aptamer, progressive library methodAlzheimer's disease, amyloid β, cDNA display, in vitro evolution, peptide aptamer, progressive library method