Fig. 5.

Proteinase K digestion of huPrP23-144 before (A) and after (B) fibrillization. Molecular weight markers are shown on the left, and the concentration of proteinase K is indicated below each line. Protein was converted to fibrillar form by incubating at a concentration of 400 μM for 12 h at 25°C in 50 mM phosphate buffer, pH 6.5. Samples of monomeric and fibrillar protein (125 μM) were digested with various amounts of proteinase K for 30 min at 37°C. The digestion was terminated by boiling for 10 min in SDS sample loading buffer. Protein fragments were separated by SDS/PAGE and visualized by Coomassie blue staining.