The central event in the pathogenesis of prion protein (PrP) is a profound conformational change from its α-helical (PrPC) to its β-sheet-rich isoform (PrPSc).Many single amino acid mutations of PrP are associated with familial prion diseases,such as D202N,E211Q,and Q217R mutations located at the third native α-helix of human PrP.