{"title":"氮酶机制中的硫化物释放和重新结合。","authors":"Per E. M. Siegbahn","doi":"10.1002/jcc.27494","DOIUrl":null,"url":null,"abstract":"<p>Nitrogenases are the only enzymes that activate the strong triple bond in N<sub>2</sub>. The mechanism for the activation has been very difficult to determine in spite of decades of work. In previous modeling studies it has been suggested that the mechanism for nitrogen activation starts out by four pre-activation steps (A<sub>0</sub>–A<sub>4</sub>) before catalysis. That suggestion led to excellent agreement with experimental Elecrtron Paramagnetic Resonance (EPR) observations in the step where N<sub>2</sub> becomes protonated (E<sub>4</sub>). An important part of the pre-activation is that a sulfide is released. In the present paper, the details of the pre-activation are modeled, including the release of the sulfide. Several possible transition states for the release have been obtained. An A<sub>4</sub>(E<sub>0</sub>) state is reached which is very similar to the E<sub>4</sub> state. For completeness, the steps going back from A<sub>4</sub>(E<sub>0</sub>) to A<sub>0</sub> after catalysis are also modeled, including the insertion of a sulfide.</p>","PeriodicalId":188,"journal":{"name":"Journal of Computational Chemistry","volume":"45 32","pages":"2835-2841"},"PeriodicalIF":3.4000,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jcc.27494","citationCount":"0","resultStr":"{\"title\":\"Sulfide release and rebinding in the mechanism for nitrogenase\",\"authors\":\"Per E. M. Siegbahn\",\"doi\":\"10.1002/jcc.27494\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Nitrogenases are the only enzymes that activate the strong triple bond in N<sub>2</sub>. The mechanism for the activation has been very difficult to determine in spite of decades of work. In previous modeling studies it has been suggested that the mechanism for nitrogen activation starts out by four pre-activation steps (A<sub>0</sub>–A<sub>4</sub>) before catalysis. That suggestion led to excellent agreement with experimental Elecrtron Paramagnetic Resonance (EPR) observations in the step where N<sub>2</sub> becomes protonated (E<sub>4</sub>). An important part of the pre-activation is that a sulfide is released. In the present paper, the details of the pre-activation are modeled, including the release of the sulfide. Several possible transition states for the release have been obtained. An A<sub>4</sub>(E<sub>0</sub>) state is reached which is very similar to the E<sub>4</sub> state. For completeness, the steps going back from A<sub>4</sub>(E<sub>0</sub>) to A<sub>0</sub> after catalysis are also modeled, including the insertion of a sulfide.</p>\",\"PeriodicalId\":188,\"journal\":{\"name\":\"Journal of Computational Chemistry\",\"volume\":\"45 32\",\"pages\":\"2835-2841\"},\"PeriodicalIF\":3.4000,\"publicationDate\":\"2024-08-27\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jcc.27494\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Computational Chemistry\",\"FirstCategoryId\":\"92\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1002/jcc.27494\",\"RegionNum\":3,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"CHEMISTRY, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Computational Chemistry","FirstCategoryId":"92","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/jcc.27494","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
Sulfide release and rebinding in the mechanism for nitrogenase
Nitrogenases are the only enzymes that activate the strong triple bond in N2. The mechanism for the activation has been very difficult to determine in spite of decades of work. In previous modeling studies it has been suggested that the mechanism for nitrogen activation starts out by four pre-activation steps (A0–A4) before catalysis. That suggestion led to excellent agreement with experimental Elecrtron Paramagnetic Resonance (EPR) observations in the step where N2 becomes protonated (E4). An important part of the pre-activation is that a sulfide is released. In the present paper, the details of the pre-activation are modeled, including the release of the sulfide. Several possible transition states for the release have been obtained. An A4(E0) state is reached which is very similar to the E4 state. For completeness, the steps going back from A4(E0) to A0 after catalysis are also modeled, including the insertion of a sulfide.
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This distinguished journal publishes articles concerned with all aspects of computational chemistry: analytical, biological, inorganic, organic, physical, and materials. The Journal of Computational Chemistry presents original research, contemporary developments in theory and methodology, and state-of-the-art applications. Computational areas that are featured in the journal include ab initio and semiempirical quantum mechanics, density functional theory, molecular mechanics, molecular dynamics, statistical mechanics, cheminformatics, biomolecular structure prediction, molecular design, and bioinformatics.
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