Quasielastic neutron scattering study of human -synuclein; Implication for propensity for amyloid fibril formation

Fujiwara, Satoru; Araki, Katsuya*; Matsuo, Tatsuhito; Yagi, Hisashi*; Yamada, Takeshi*; Shibata, Kaoru  ; Mochizuki, Hideki*

A protein -synuclein (-Syn) forms amyloid fibrils. This abnormal protein aggregation is related to pathogenesis of a neuro-degenerative disorder, Parkinson's disease. Propensity for amyloid fibril formation depends on environmental conditions such as pH. We carried out quasielastic neutron scattering experiments to investigate the "dynamic" behavior of -Syn to investigate the relationship between the dynamics and propensity for amyloid fibril formation. The measurements on the solution samples of -Syn in different pH were carried out using a high energy resolution near-backscattering spectrometer, BL02 (DNA), at MLF/J-PARC, Japan. Differences in flexibility of the protein were detected between the different conditions. Since the difference in flexibility is likely to arise from different distributions of conformational substates of -Syn, the results obtained suggest an entropy-driven mechanism of the amyloid fibril formation.