Conversion of a-helices into b-sheets features in the formation of the scrapie prion proteins - Pan, K-M; Baldwin, M; Nguyen, J; Gasset, M; Serban, A; Groth, D; Mehlhorn, I; Huang, Z; Fletterick, RJ; Cohen, FE; Prusiner, SB (Proc Natl Acad Sci USA, 1993)