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Using electrochemical poising of protein crystals, together with in crystallo EPR spectroscopic verification of the redox state, we obtain structures showing the P-cluster at PN, P1+, P2+, and P3+ levels. This provides a detailed structural characterization of P-cluster rearrangement between the catalytically relevant PN and P1+ levels and the first experimental confirmation that the S = 7\/2 P3+ state is structurally similar to P2+. These studies pave the way for future understanding of the structure\u2013function relationship in nitrogenase catalysis.<\/jats:p>","DOI":"10.1021\/jacs.6c08522","type":"journal-article","created":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T09:27:57Z","timestamp":1788254877000},"page":"37583-37588","source":"Crossref","is-referenced-by-count":0,"title":["Structural\nCharacterization of Four Redox States of\nthe P-cluster in Molybdenum Nitrogenase via Electrochemical\nControl of Crystals"],"prefix":"10.1021","volume":"148","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2526-7433","authenticated-orcid":true,"given":"Shoba","family":"Laxmi","sequence":"first","affiliation":[{"name":"University of Oxford, Inorganic Chemistry Laboratory , , South Parks Road , ,","place":["Oxford, U.K., OX1 3QR"]},{"name":"Rutherford Appleton Laboratory , , Harwell Campus , ,","place":["Didcot, U.K., OX11 0QX"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"William K.","family":"Myers","sequence":"additional","affiliation":[{"name":"University of Oxford, Inorganic Chemistry Laboratory , , South Parks Road , ,","place":["Oxford, U.K., OX1 3QR"]},{"name":"University of Oxford , , ,","place":["Oxford, U.K., OX1 3QR"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8186-9450","authenticated-orcid":true,"given":"Zhi-Yong","family":"Yang","sequence":"additional","affiliation":[{"name":"Utah State University , , , ,","place":["Logan, Utah, United States, 84322"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6457-9504","authenticated-orcid":true,"given":"Lance C.","family":"Seefeldt","sequence":"additional","affiliation":[{"name":"Utah State University , , , ,","place":["Logan, Utah, United States, 84322"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1473-457X","authenticated-orcid":true,"given":"Stephen B.","family":"Carr","sequence":"additional","affiliation":[{"name":"University of Oxford, Inorganic Chemistry Laboratory , , South Parks Road , ,","place":["Oxford, U.K., OX1 3QR"]},{"name":"Rutherford Appleton Laboratory , , Harwell Campus , ,","place":["Didcot, U.K., OX11 0QX"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6444-9382","authenticated-orcid":true,"given":"Kylie A.","family":"Vincent","sequence":"additional","affiliation":[{"name":"University of Oxford, Inorganic Chemistry Laboratory , , South Parks Road , ,","place":["Oxford, U.K., OX1 3QR"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,8,26]]},"reference":[{"issue":"6391","key":"2026090910081575900_cit1","doi-asserted-by":"publisher","DOI":"10.1126\/science.aar6611","article-title":"Beyond fossil fuel\u2013driven nitrogen transformations","volume":"360","author":"Chen","year":"2018","journal-title":"Science"},{"issue":"7","key":"2026090910081575900_cit2","doi-asserted-by":"publisher","first-page":"490","DOI":"10.1038\/s41929-018-0092-7","article-title":"Catalysts for nitrogen reduction\nto ammonia","volume":"1","author":"Foster","year":"2018","journal-title":"Nature Catalysis"},{"issue":"28","key":"2026090910081575900_cit3","doi-asserted-by":"publisher","first-page":"10572","DOI":"10.1021\/acssuschemeng.0c03675","article-title":"Enhanced Electrochemical\nReduction of N2 to Ammonia over Pyrite FeS2 with Excellent\nSelectivity","volume":"8","author":"Du","year":"2020","journal-title":"ACS Sustainable Chem. 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