Fig. 2.

EPR signals obtained from fibrils generated by using D178N huPrP 90–231 labeled at indicated positions. For clarity of presentation, spectra displaying a high degree of spin exchange are shown in red, and those spectra affected largely by dipolar broadening are shown in black. Spectra for spin-diluted fibrils generated by using a 1:4 ratio of labeled to unlabeled protein are shown as gray lines. Scan width is 200 G, and spectral pairs for each site are scaled to the same number of spins.