{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T00:43:22Z","timestamp":1790642602326,"version":"4.1.0"},"reference-count":60,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2019,3,22]],"date-time":"2019-03-22T00:00:00Z","timestamp":1553212800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["R01-GM122441"],"award-info":[{"award-number":["R01-GM122441"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100001233","name":"William G. McGowan Charitable Fund","doi-asserted-by":"publisher","award":["none"],"award-info":[{"award-number":["none"]}],"id":[{"id":"10.13039\/100001233","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Carnegie\/DOE Alliance Center","award":["none"],"award-info":[{"award-number":["none"]}]},{"DOI":"10.13039\/100000879","name":"Alfred P. Sloan Foundation","doi-asserted-by":"publisher","award":["none"],"award-info":[{"award-number":["none"]}],"id":[{"id":"10.13039\/100000879","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Department of Energy\/National Nuclear Security Administration","award":["DE-NA-0002006"],"award-info":[{"award-number":["DE-NA-0002006"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Determining the effects of extreme conditions on proteins from \u201cextremophilic\u201d and mesophilic microbes is important for understanding how life adapts to living at extremes as well as how extreme conditions can be used for sterilization and food preservation. Previous molecular dynamics simulations of dihydrofolate reductase (DHFR) from a psychropiezophile (cold- and pressure-loving), Moritella profunda (Mp), and a mesophile, Escherichia coli (Ec), at various pressures and temperatures indicate that atomic fluctuations, which are important for enzyme function, increase with both temperature and pressure. Here, the factors that cause increases in atomic fluctuations in the simulations are examined. The fluctuations increase with temperature not only because of greater thermal energy and thermal expansion of the protein but also because hydrogen bonds between protein atoms are weakened. However, the increase in fluctuations with pressure cannot be due to thermal energy, which remains constant, nor the compressive effects of pressure, but instead, the hydrogen bonds are also weakened. In addition, increased temperature causes larger increases in fluctuations of the loop regions of MpDHFR than EcDHFR, and increased pressure causes both increases and decreases in fluctuations of the loops, which differ between the two.<\/jats:p>","DOI":"10.3390\/ijms20061452","type":"journal-article","created":{"date-parts":[[2019,3,25]],"date-time":"2019-03-25T06:56:52Z","timestamp":1553497012000},"page":"1452","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["Effects of Pressure and Temperature on the Atomic Fluctuations of Dihydrofolate Reductase from a Psychropiezophile and a Mesophile"],"prefix":"10.3390","volume":"20","author":[{"given":"Qi","family":"Huang","sequence":"first","affiliation":[{"name":"Department of Chemistry, Georgetown University, Washington, DC 20057, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jocelyn M.","family":"Rodgers","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Georgetown University, Washington, DC 20057, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Russell J.","family":"Hemley","sequence":"additional","affiliation":[{"name":"Department of Civil and Environmental Engineering, George Washington University, Washington, DC 20052, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2474-5253","authenticated-orcid":false,"given":"Toshiko","family":"Ichiye","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Georgetown University, Washington, DC 20057, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,3,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e9","DOI":"10.1017\/S0033583516000044","article-title":"Thermal protein unfolding by differential scanning calorimetry and circular dichroism spectroscopy Two-state model versus sequential unfolding","volume":"49","author":"Seelig","year":"2016","journal-title":"Q. 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