Mass spectrometry-based approaches to mapping the surfaces of the infectious protein (prion) conformations of chronic wasting disease (CWD) and scrapie

Authors: Silva, Christopher

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2026
Publication Date: 3/10/2026
Citation: Silva, C.J. 2026. Mass spectrometry-based approaches to mapping the surfaces of the infectious protein (prion) conformations of chronic wasting disease (CWD) and scrapie. Chemistry Department Seminar, March 10, 2026. University at Albany, State University of New York. Meeting Abstract. 2026.

Interpretive Summary:

Technical Abstract: Prions are infectious proteins that cause transmissible spongiform encephalopathies (TSEs), such as cervid chronic wasting disease (CWD) and sheep scrapie. CWD and scrapie infections can occur sporadically or be transmitted from infected animals or prion contaminated environments. Prions (PrPSc) amplify by inducing a natively expressed prion protein (PrPC) to adopt the PrPSc conformation. PrPSc and PrPC possess identical primary structures and post-translational covalent modifications. PrPSc and PrPC phenotypes result from conformational differences. The secondary structure of PrPC is composed of random coil (66.5%), a-helix (31.4%), and ß-sheet (2%). The secondary structure of PrPSc is largely ß-sheet, with no a-helix. In the ß-sheet, adjacent amino acid side chains project in opposite perpendicular directions to the plane of the ß-sheet. PrPC is highly conserved among mammals and contains a disproportionately greater number of methionines than other mammalian proteins, six of which are common to most mammalian species. Methionine is labile to oxidation with hydrogen peroxide, converting it to the corresponding sulfoxide. Hydrogen peroxide mediated oxidation does not perturb the prion conformation. The extent of the reaction is determined by the surface exposure of a methionine, as all methionines are equally susceptible to hydrogen peroxide oxidation. Methionine sulfoxide is a covalent transformation that survives the conformation destroying denaturation required for analysis. Thus, oxidizing prions with hydrogen peroxide is a means of mapping a prion’s surface that is retained after denaturation and analysis. Samples of purified scrapie and CWD prions were oxidized with hydrogen peroxide. The oxidized samples were denatured, reduced, alkylated, and digested with proteases (trypsin and/or chymotrypsin, or ArgC). The resulting peptides were analyzed by a multiple reaction monitoring (MRM) method to determine the extent of methionine oxidation. The approach allowed us to distinguish among strains of scrapie and CWD.