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Virus Res. 2015 Sep 2;207:120-6. doi: 10.1016/j.virusres.2015.03.008. Epub 2015 Mar 24.

Proteinase K and the structure of PrPSc: The good, the bad and the ugly.

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United States Department of Agriculture, Agricultural Research Service, Produce Safety & Microbiology Research Unit, 800 Buchanan Street, Albany, CA, USA. Electronic address:
Centre for Prions and Protein Folding Diseases, University of Alberta, Brain and Aging Research Building, Room 230A, Edmonton, AB T6G 2M8 Canada.
OniPro, Kensington, CA, USA.
CIMUS Biomedical Research Institute, University of Santiago de Compostela-IDIS, Room SS1D, Avenida de Barcelona s/n, 15782 Santiago de Compostela, Spain. Electronic address:


Infectious proteins (prions) are, ironically, defined by their resistance to proteolytic digestion. A defining characteristic of the transmissible isoform of the prion protein (PrP(Sc)) is its partial resistance to proteinase K (PK) digestion. Diagnosis of prion disease typically relies upon immunodetection of PK-digested PrP(Sc) by Western blot, ELISA or immunohistochemical detection. PK digestion has also been used to detect differences in prion strains. Thus, PK has been a crucial tool to detect and, thereby, control the spread of prions. PK has also been used as a tool to probe the structure of PrP(Sc). Mass spectrometry and antibodies have been used to identify PK cleavage sites in PrP(Sc). These results have been used to identify the more accessible, flexible stretches connecting the β-strand components in PrP(Sc). These data, combined with physical constraints imposed by spectroscopic results, were used to propose a qualitative model for the structure of PrP(Sc). Assuming that PrP(Sc) is a four rung β-solenoid, we have threaded the PrP sequence to satisfy the PK proteolysis data and other experimental constraints.


Limited proteolysis; PrP(Sc); PrP(Sc) structure; Prion; Proteinase K; β-Solenoid

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