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Studies on the hydrogenation steps of the nitrogen molecule at the Azotobacter vinelandii nitrogenase site
Author(s) -
Stavrev Krassimir K.,
Zerner Michael C.
Publication year - 1998
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/(sici)1097-461x(1998)70:6<1159::aid-qua5>3.0.co;2-z
Subject(s) - nitrogenase , chemistry , molecule , protonation , azotobacter vinelandii , density functional theory , concerted reaction , computational chemistry , nitrogen , catalysis , photochemistry , nitrogen fixation , ion , organic chemistry
We follow the initial activation of the nitrogen molecule at the FeMo cofactor of nitrogenase and subsequently model the hydrogenation of N 2 up to the fourth protonation step using the intermediate neglect of differential overlap quantum‐chemical model. The results obtained favor a reaction mechanism going through hydrazido intermediates on the 4‐Fe surfaces, externally to the FeMo cofactor. Calculations using density functional theory on smaller model systems also support the suggested mechanism over other possible schemes that involve early release of the first molecule of ammonia as a product of the enzymatic reaction. We also demonstrate that dielectric stabilization due to the protein around the cofactor could lower markedly the barrier for the product release as an ammonium ion. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 1159–1168, 1998