Figure 1. Characterization of rPrP^C, rPrP^8OR and rPrP^10OR.

(A) Freshly prepared rPrP^C, rPrP^8OR and rPrP^10OR proteins were separated by SDS/PAGE under non-reducing conditions and then immunoblotted with mAb 8H4. Molecular-mass (Mol. Wt.) markers are indicated in kDa to the left-hand side of the panel. (B) Acidic native gel electrophoresis of rPrP^C, rPrP^8OR and rPrP^10OR. The gel was stained with Coomassie Blue. All three recombinant proteins exist as monomers under these conditions. (C) Far-UV CD spectra of rPrP^C, rPrP^8OR and rPrP^10OR. The spectra were obtained using 20 μM of rPrP^C (dotted line), rPrP^8OR (broken line) and rPrP^10OR (solid line) in 20 mM sodium acetate (pH 5.5). While rPrP^C and rPrP^8OR have rather similar secondary structures, rPrP^10OR has a small decrease in the negativity of the spectra. Therefore insertion mutations at the N-terminus are able to influence the secondary structure of the molecule, depending on the number of octapeptide-repeat inserts.