Short polyglutamine peptide forms a high-affinity binding site for thioflavin-T at the N-terminus.

摘要: Thioflavin-T is one of the most important amyloid specific dyes and has been used for more than 50 years; however, molecular mechanism staining still not understood. Chemically synthesized short polyglutamine peptides (Qn, n = 5–10) were subjected to thioflavin-T (ThT) assay. It was found that minimum Qn peptide stained positive ThT Q6. Two types ThT-binding sites, a high-affinity site (kd1 0.1–0.17 μM) low-affinity (kd2 5.7–7.4 μM), observed in polyQs (n 6–9). 13C{2H}REDOR NMR experiments carried out extract local structure binding sites Q8 aggregates by observing intermolecular dipolar coupling between [3-Me-d3]ThT natural abundance or residue-specific [1,2-13C2] labeled Q8s. difference spectra [3-Me-d3]ThT/natural (1/9) complex indicated all five carbons glutamine residue participated formation sites. 13C{2H}DQF–REDOR [3-Me-d3]ThT/residue-specific (1/50) complexes demonstrated N-terminal had direct contact with molecule at