Fig. 2.

Conformation of the loop of residues 166–176 in PrP^C from different species and corresponding NMR spectra. (A) Polypeptide backbone of ePrP (121–231) represented by a spline function through the C^α positions. The radius of the gray cylindrical rod is proportional to the mean global backbone displacement per residue, as evaluated after superposition for best fit of the atoms N, C^α, and C′ of the residues 125–228 in the bundle of 20 energy-minimized conformers used to represent the NMR structure (Fig. 1 A). The region comprising residues 166–175 is highlighted in red. (B) Same as A for mPrP[S170N,N174T], with the residues 166–175 in blue. (C) Same as A for mPrP[N174T]. For residues 166–175, the cylindrical rod is yellow; where no backbone resonances could be observed, the cylindrical rod is drawn as a broken line. (D) Same as C for wild-type mPrP, with residues 166–175 in green. (E) 3D HNCA spectrum of ePrP(121–231). Strips are displayed for the residues 166–176, with sequential and intraresidual C^α–C^α connectivities indicated with red lines. The strip containing Phe-175 has been drawn with lower contour levels to show the weak sequential signal. (F) Same presentation as in E for mPrP(121–231), with the observed sequential and intraresidual C^α–C^α connectivities indicated with green lines.