Scrapie agent contains a hydrophobic protein.

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Abstract
The scrapie agent causes a degenerative nervous system disorder of sheep and goats. Considerable evidence indicates that the scrapie agent contains a protein that is necessary for infectivity, but direct demonstration of a protein moiety has been hampered by lack of sufficiently purified preparations. Employing preparations of the scrapie agent enriched 100- to 1000-fold with respect to protein, digestion by proteinase K destroyed > 99.9% of the infectivity. Diethylpyrocarbonate, which chemically modifies amino acid residues in proteins with high efficiency, also inactivated the scrapie agent in these purified preparations. Reductions of infectivity by proteinase K and diethylpyrocarbonate were not observed with less purified preparations. The agent bound to phenyl-Sepharose could not be eluted with 8.5 M ethylene glycol; a combination of ethylene glycol and detergents did release the agent. Thus evidence for a protein and for hydrophobic domains within the scrapie agent is provided. Whether the protein required for infectivity is the same protein responsible for the hydrophobic properties of the scrapie agent remains to be established.