{"title":"固氮酶固氮机制的最后 E5 至 E8 步骤。","authors":"Per E M Siegbahn","doi":"10.1021/acs.jpcb.4c04331","DOIUrl":null,"url":null,"abstract":"<p><p>Nitrogenase converts nitrogen in the air to ammonia. It is often regarded as the second most important enzyme in nature after photosystem II. The mechanism for how nitrogenase is able to perform the difficult task of cleaving the strong bond in N<sub>2</sub> is debated. It is known that for every electron that is donated to N<sub>2</sub>, two ATP are hydrolyzed. In the experimentally suggested mechanism, the activation occurs after four reductions of the ground state, but there is no suggestion for how the enzyme uses the hydrolysis energy to perform catalysis. In the theoretical mechanism, it is suggested that hydrolysis is used to reduce the electron donor. In previous papers, the steps leading to the activation of N<sub>2</sub> in the so-called E<sub>4</sub> state has been investigated, using both the experimental and theoretical mechanism, showing that only the theoretical one leads to agreement with EPR observations for E<sub>4</sub>. In the present paper, the four steps following E<sub>4</sub>, leading to the release of two ammonia molecules, are described using the same methodology as used in the previous studies.</p>","PeriodicalId":60,"journal":{"name":"The Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":2.8000,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Final E<sub>5</sub> to E<sub>8</sub> Steps in the Nitrogenase Mechanism for Nitrogen Fixation.\",\"authors\":\"Per E M Siegbahn\",\"doi\":\"10.1021/acs.jpcb.4c04331\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>Nitrogenase converts nitrogen in the air to ammonia. It is often regarded as the second most important enzyme in nature after photosystem II. The mechanism for how nitrogenase is able to perform the difficult task of cleaving the strong bond in N<sub>2</sub> is debated. It is known that for every electron that is donated to N<sub>2</sub>, two ATP are hydrolyzed. In the experimentally suggested mechanism, the activation occurs after four reductions of the ground state, but there is no suggestion for how the enzyme uses the hydrolysis energy to perform catalysis. In the theoretical mechanism, it is suggested that hydrolysis is used to reduce the electron donor. In previous papers, the steps leading to the activation of N<sub>2</sub> in the so-called E<sub>4</sub> state has been investigated, using both the experimental and theoretical mechanism, showing that only the theoretical one leads to agreement with EPR observations for E<sub>4</sub>. In the present paper, the four steps following E<sub>4</sub>, leading to the release of two ammonia molecules, are described using the same methodology as used in the previous studies.</p>\",\"PeriodicalId\":60,\"journal\":{\"name\":\"The Journal of Physical Chemistry B\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.8000,\"publicationDate\":\"2024-10-10\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"The Journal of Physical Chemistry B\",\"FirstCategoryId\":\"1\",\"ListUrlMain\":\"https://doi.org/10.1021/acs.jpcb.4c04331\",\"RegionNum\":2,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"2024/9/30 0:00:00\",\"PubModel\":\"Epub\",\"JCR\":\"Q3\",\"JCRName\":\"CHEMISTRY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Journal of Physical Chemistry B","FirstCategoryId":"1","ListUrlMain":"https://doi.org/10.1021/acs.jpcb.4c04331","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/9/30 0:00:00","PubModel":"Epub","JCR":"Q3","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
Final E5 to E8 Steps in the Nitrogenase Mechanism for Nitrogen Fixation.
Nitrogenase converts nitrogen in the air to ammonia. It is often regarded as the second most important enzyme in nature after photosystem II. The mechanism for how nitrogenase is able to perform the difficult task of cleaving the strong bond in N2 is debated. It is known that for every electron that is donated to N2, two ATP are hydrolyzed. In the experimentally suggested mechanism, the activation occurs after four reductions of the ground state, but there is no suggestion for how the enzyme uses the hydrolysis energy to perform catalysis. In the theoretical mechanism, it is suggested that hydrolysis is used to reduce the electron donor. In previous papers, the steps leading to the activation of N2 in the so-called E4 state has been investigated, using both the experimental and theoretical mechanism, showing that only the theoretical one leads to agreement with EPR observations for E4. In the present paper, the four steps following E4, leading to the release of two ammonia molecules, are described using the same methodology as used in the previous studies.
期刊介绍:
An essential criterion for acceptance of research articles in the journal is that they provide new physical insight. Please refer to the New Physical Insights virtual issue on what constitutes new physical insight. Manuscripts that are essentially reporting data or applications of data are, in general, not suitable for publication in JPC B.