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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #424447
Research Project: Rapid Antemortem Tests for the Early Detection of Transmissible Spongiform Encephalopathies and Other Animal Diseases

Location: Produce Safety and Microbiology Research

Title: Mass spectrometry-based sequencing of prion protein conformations

Author
item Silva, Christopher
item Erickson-Beltran, Melissa
item REQUENA, JESUS - University Of Santiago De Compostela

Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/28/2025
Publication Date: 8/18/2025
Citation: Silva, C.J., Erickson-Beltran, M.L., Requena, J.R. 2025. Mass spectrometry-based sequencing of prion protein conformations. American Chemical Society Abstracts. ACS Fall 2025/Abstract #4309757. https://doi.org/10.1021/scimeetings.5c11363.
DOI: https://doi.org/10.1021/scimeetings.5c11363

Interpretive Summary:

Technical Abstract: Prions (PrPSc) are infectious proteins comprised of multimers of refolded conformers of a natively expressed cellular prion protein (PrPC). Denaturing PrPSc is necessary for analysis, but doing so destroys its conformation. PrPC and its conformer PrPSc are comprised of a disproportionately greater number of methionines than is typical for a mammalian protein. A prion’s methionines can be oxidized by hydrogen peroxide without perturbing the prion conformation. A methionine’s susceptibility to oxidation is dependent upon its surface exposure. We developed a method to detect six tryptic or tryptic/chymotryptic peptides (TNMK, MLGSAMSR, ENMYR, IMER, VVEQMCITQYQR) that contain all of the methionines in sheep PrP. Samples of sheep recombinant PrP (rPrP) and sheep scrapie were oxidized with four different concentrations of hydrogen peroxide (0, 5, 10, or 20 mM). Oxidation of the methionines in sheep rPrP was consistent with the surface exposure calculated from the crystal structure. The structure of sheep scrapie is not known, but the extent of methionine oxidation (216 > 137 > 132 > 157 > 209 > 112) was different from that of sheep rPrP. These results show that methionine oxidation is dependent upon surface exposure and is consistent with the surface exposure derived from a known structure (rPrP). They suggest that this approach quantifies the surface exposure of the methionines in scrapie prions and, thereby, effects a kind of conformational sequencing.