{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T12:52:29Z","timestamp":1791895949592,"version":"4.3.4"},"reference-count":36,"publisher":"Wiley","issue":"9","license":[{"start":{"date-parts":[[2026,8,9]],"date-time":"2026-08-09T00:00:00Z","timestamp":1786233600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"},{"start":{"date-parts":[[2026,8,9]],"date-time":"2026-08-09T00:00:00Z","timestamp":1786233600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/501100000038","name":"Natural Sciences and Engineering Research Council of Canada","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100000038","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Protein Science"],"published-print":{"date-parts":[[2026,9]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    The SARS\u2010CoV\u20102 main protease (M\n                    <jats:sup>pro<\/jats:sup>\n                    ) is essential for viral replication and functions as a homodimer, with dimerization being critical for catalytic activity. M\n                    <jats:sup>pro<\/jats:sup>\n                    contains an unusually high number of cysteine residues. Among these, C117 and the catalytic nucleophile C145 can form a reversible disulfide bond under oxidative conditions. To investigate the structural and functional consequences of irreversible oxidation of these residues, we generated oxidation mimics by substituting these residues with aspartate (C117D and C145D), to mimic the sulfinic acid oxidation state. Kinetic assays revealed that both variants are catalytically inactive, with C117D exhibiting at least 100\u2010fold lower activity than wild\u2010type (WT) M\n                    <jats:sup>pro<\/jats:sup>\n                    . Small\u2010angle X\u2010ray scattering (SAXS) and differential scanning fluorimetry (DSF) demonstrated that C117D adopts a monomeric, destabilized state in solution, whereas C145D retains a dimeric conformation similar to WT. Crystallographic analysis of C117D revealed a dramatic rearrangement of domain III, involving a ~40\u00b0 rotation relative to domains I and II, and disorder in the N\u2010 and C\u2010terminal regions, disrupting the canonical dimerization interface. Local structural changes propagated from the C117D site to the active site, including an unwound oxyanion loop that provides structural evidence for the observed inactivity. Rescue of the stable, dimeric state for C117D was achieved through formation of the covalent C117D\u2010GC376 complex. These findings establish a high\u2010resolution structure of monomeric full\u2010length SARS\u2010CoV\u20102 M\n                    <jats:sup>pro<\/jats:sup>\n                    and underscore a critical role of C117 in maintaining dimerization and enzymatic function. Furthermore, the unique monomeric domain II\u2010III interface present in the monomeric form may offer opportunities for allosteric inhibitor design targeting M\n                    <jats:sup>pro<\/jats:sup>\n                    dimerization.\n                  <\/jats:p>","DOI":"10.1002\/pro.70753","type":"journal-article","created":{"date-parts":[[2026,8,10]],"date-time":"2026-08-10T04:27:22Z","timestamp":1786336042000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["The\n                    <scp>C117D<\/scp>\n                    oxidation mimic reveals the monomeric structure of\n                    <scp>SARS<\/scp>\n                    \u2010\n                    <scp>CoV<\/scp>\n                    \u20102 main protease"],"prefix":"10.1002","volume":"35","author":[{"given":"Sam","family":"Andress","sequence":"first","affiliation":[{"name":"Department of Biology University of Waterloo  Ontario Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5540-916X","authenticated-orcid":false,"given":"Matthew J.","family":"McLeod","sequence":"additional","affiliation":[{"name":"Department of Chemistry University of Cincinnati  Cincinnati Ohio USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7329-1115","authenticated-orcid":false,"given":"Todd","family":"Holyoak","sequence":"additional","affiliation":[{"name":"Department of Biology University of Waterloo  Ontario 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