{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T13:46:51Z","timestamp":1785851211059,"version":"3.56.0"},"reference-count":32,"publisher":"American Society for Microbiology","issue":"8","license":[{"start":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T00:00:00Z","timestamp":1785888000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T00:00:00Z","timestamp":1785888000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"funder":[{"DOI":"10.13039\/100005564","name":"Gilead Sciences","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100005564","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["Antimicrob Agents Chemother"],"published-print":{"date-parts":[[2026,8,5]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title\/>\n                    <jats:p>\n                      Obeldesivir (GS-5245, ODV), an orally administered 5\u2032-isobutyryl ester prodrug of GS-441524, has demonstrated anti-SARS-CoV-2 activity in preclinical and clinical settings. ODV is hydrolyzed in plasma to provide high systemic exposures of GS-441524, enabling the efficient intracellular formation of the bioactive 5\u2032-triphosphate GS-443902, an ATP analog inhibiting the SARS-CoV-2 RNA-dependent RNA polymerases. Remdesivir (RDV), the first US FDA-approved antiviral treatment for COVID-19, is also activated to GS-443902. In this paper, we systematically profiled the human enzymes potentially involved in ODV and RDV activation using multiple approaches: (i) biochemical studies on the catalytic efficiency (\n                      <jats:italic toggle=\"yes\">k<\/jats:italic>\n                      <jats:sub>cat<\/jats:sub>\n                      \/\n                      <jats:italic toggle=\"yes\">K<\/jats:italic>\n                      <jats:sub>m<\/jats:sub>\n                      ); (ii) analysis of activation in single-gene knockout cells; and (iii) the antiviral activity assessment in single-gene knockout cells. Our results demonstrated that ODV hydrolysis to GS-441524 is catalyzed by carboxylesterase 1 and 2 with high efficiency. For the enzymes involved in the consecutive formation of 5\u2032-mono-, di-, and tri-phosphates (MP, DP, and TP), adenosine kinase (ADK) likely plays a minor role in forming GS-441524-MP, suggesting the involvement of other phosphotransferases. This was further supported by cell-based single-gene ADK-knockout studies. In contrast, both biochemical and cell-based assay data strongly support adenylate kinase 2 as the key enzyme for the phosphorylation of GS-441524-MP, while nucleoside diphosphate kinase NM23-H2, phosphoglycerate kinase, and pyruvate kinase likely all contribute to the formation of GS-441524-TP. This work leads to a deeper understanding of ODV and RDV metabolism, and suggests further studies are needed to identify the enzyme responsible for the activation of GS-441524 to its 5\u2032-monophosphate.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1128\/aac.00055-26","type":"journal-article","created":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T12:00:44Z","timestamp":1782129644000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Identification of key metabolic enzymes involved in the activation of obeldesivir and remdesivir to the active triphosphate metabolite"],"prefix":"10.1128","volume":"70","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0083-799X","authenticated-orcid":true,"given":"Yili","family":"Xu","sequence":"first","affiliation":[{"name":"Gilead Sciences, Inc.","place":["Foster City, 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