{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T03:10:01Z","timestamp":1787627401567,"version":"build-2736575974"},"reference-count":56,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2024,6,17]],"date-time":"2024-06-17T00:00:00Z","timestamp":1718582400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institute on Drug Abuse\u2013Intramural Research Program","doi-asserted-by":"publisher","award":["Z1A DA000606"],"award-info":[{"award-number":["Z1A DA000606"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"National Institute on Drug Abuse\u2013Intramural Research Program","doi-asserted-by":"publisher","award":["Z1A DA000389"],"award-info":[{"award-number":["Z1A DA000389"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biomolecules"],"abstract":"<jats:p>Modafinil analogs with either a sulfoxide or sulfide moiety have improved binding affinities at the human dopamine transporter (hDAT) compared to modafinil, with lead sulfoxide-substituted analogs showing characteristics of atypical inhibition (e.g., JJC8-091). Interestingly, the only distinction between sulfoxide and sulfide substitution is the presence of one additional oxygen atom. To elucidate why such a subtle difference in ligand structure can result in different typical or atypical profiles, we investigated two pairs of analogs. Our quantum mechanical calculations revealed a more negatively charged distribution of the electrostatic potential surface of the sulfoxide substitution. Using molecular dynamics simulations, we demonstrated that sulfoxide-substituted modafinil analogs have a propensity to attract more water into the binding pocket. They also exhibited a tendency to dissociate from Asp79 and form a new interaction with Asp421, consequently promoting an inward-facing conformation of hDAT. In contrast, sulfide-substituted analogs did not display these effects. These findings elucidate the structural basis of the activity cliff observed with modafinil analogs and also enhance our understanding of the functionally relevant conformational spectrum of hDAT.<\/jats:p>","DOI":"10.3390\/biom14060713","type":"journal-article","created":{"date-parts":[[2024,6,17]],"date-time":"2024-06-17T11:14:16Z","timestamp":1718622856000},"page":"713","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["The Structural Basis of the Activity Cliff in Modafinil-Based Dopamine Transporter Inhibitors"],"prefix":"10.3390","volume":"14","author":[{"given":"Kuo-Hao","family":"Lee","sequence":"first","affiliation":[{"name":"Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse\u2013Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gisela Andrea","family":"Camacho-Hernandez","sequence":"additional","affiliation":[{"name":"Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse\u2013Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amy Hauck","family":"Newman","sequence":"additional","affiliation":[{"name":"Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse\u2013Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4137-096X","authenticated-orcid":false,"given":"Lei","family":"Shi","sequence":"additional","affiliation":[{"name":"Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse\u2013Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,6,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"585","DOI":"10.1124\/pr.108.000869","article-title":"SLC6 neurotransmitter transporters: Structure, function, and regulation","volume":"63","author":"Kristensen","year":"2011","journal-title":"Pharmacol. 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