SCRAPIE INFECTIVITY CORRELATES WITH CONVERTING ACTIVITY, PROTEASE RESISTANCE, AND AGGREGATION OF SCRAPIE-ASSOCIATED PRION PROTEIN IN GUANIDINE DENATURATION STUDIES

Denaturation studies with guanidine HCl (GdnHCl) were performed to tes t the relationship between scrapie infectivity and properties of scrap ie-associated prion protein (PrPSc). Large GdnHCl-induced reductions i n infectivity were associated,vith the irreversible elimination of bot h the proteinase K resistance and apparent self-propagating converting activity of PrPSc. In intermediate GdnHCl concentrations that stimula te converting activity and partially disaggregate PrPSc, both scrapie infectivity and converting activity were associated with residual part ially protease-resistant multimers of PrPSc.