| 研究実績の概要 |
We have successfully fused the amyloid peptides (Amyloid beta and Alpha-synuclein) at the C-terminal of the ferritin cage and thus, isolated a precise number of such peptides into a confined protein environment. For amyloid beta which is a 42-residue peptide, the ferritin maintained the 24-mer spherical cage. The encapsulated peptide formed beta-sheet structure inside the cage which is confirmed by the ThT assay and Fr-IR analysis. We studied the movement fo the ferritin cage and the disassembly of the cage which expose the encapsulated amyloid beta oligomer surrounded by the ferritin subunits. For alpha-synuclein which is a 140 amino acid residue, ferritin cage did not formed due the length of the peptide. Therefore, we divided the peptide into three sections after analyzing the structure. The residue 61-95 which is mostly responsible for the beta-sheet formation was chosen and fused with the C-terminal of the ferritin cage. Ferritin cage was formed with such fragment which was characterized by MALDI however, the X-ray crystal structure did not show the position of the encapsulated peptides indicating that the peptides are dynamic in the cage. Using high-speed AFM, we observed the oligomeric state of alpha-synuclein by disassembling ferritin cage. Unlike amyloid beta peptide, the alpha-synuclein oligomer dissociates with time. Overall, our studies demonstrated the precise encapsulation of amylogenic peptides into a restricted space which usually difficult to study in solution.
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