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Proton Transfer Pathways in Nitrogenase with and without Dissociated S2B

Nitrogenase is the only enzyme that can convert N(2) to NH(3). Crystallographic structures have indicated that one of the sulfide ligands of the active‐site FeMo cluster, S2B, can be replaced by an inhibitor, like CO and OH(−), and it has been suggested that it may be displaced also during the norma...

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Autores principales: Jiang, Hao, Svensson, Oskar K. G., Cao, Lili, Ryde, Ulf
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9804283/
https://www.ncbi.nlm.nih.gov/pubmed/35920055
http://dx.doi.org/10.1002/anie.202208544
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author Jiang, Hao
Svensson, Oskar K. G.
Cao, Lili
Ryde, Ulf
author_facet Jiang, Hao
Svensson, Oskar K. G.
Cao, Lili
Ryde, Ulf
author_sort Jiang, Hao
collection PubMed
description Nitrogenase is the only enzyme that can convert N(2) to NH(3). Crystallographic structures have indicated that one of the sulfide ligands of the active‐site FeMo cluster, S2B, can be replaced by an inhibitor, like CO and OH(−), and it has been suggested that it may be displaced also during the normal reaction. We have investigated possible proton transfer pathways within the FeMo cluster during the conversion of N(2)H(2) to two molecules of NH(3), assuming that the protons enter the cluster at the S3B, S4B or S5A sulfide ions and are then transferred to the substrate. We use combined quantum mechanical and molecular mechanical (QM/MM) calculations with the TPSS and B3LYP functionals. The calculations indicate that the barriers for these reactions are reasonable if the S2B ligand remains bound to the cluster, but they become prohibitively high if S2B has dissociated. This suggests that it is unlikely that S2B reversibly dissociates during the normal reaction cycle.
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spelling pubmed-98042832023-01-03 Proton Transfer Pathways in Nitrogenase with and without Dissociated S2B Jiang, Hao Svensson, Oskar K. G. Cao, Lili Ryde, Ulf Angew Chem Int Ed Engl Research Articles Nitrogenase is the only enzyme that can convert N(2) to NH(3). Crystallographic structures have indicated that one of the sulfide ligands of the active‐site FeMo cluster, S2B, can be replaced by an inhibitor, like CO and OH(−), and it has been suggested that it may be displaced also during the normal reaction. We have investigated possible proton transfer pathways within the FeMo cluster during the conversion of N(2)H(2) to two molecules of NH(3), assuming that the protons enter the cluster at the S3B, S4B or S5A sulfide ions and are then transferred to the substrate. We use combined quantum mechanical and molecular mechanical (QM/MM) calculations with the TPSS and B3LYP functionals. The calculations indicate that the barriers for these reactions are reasonable if the S2B ligand remains bound to the cluster, but they become prohibitively high if S2B has dissociated. This suggests that it is unlikely that S2B reversibly dissociates during the normal reaction cycle. John Wiley and Sons Inc. 2022-08-19 2022-09-26 /pmc/articles/PMC9804283/ /pubmed/35920055 http://dx.doi.org/10.1002/anie.202208544 Text en © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH https://creativecommons.org/licenses/by-nc/4.0/This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc/4.0/ (https://creativecommons.org/licenses/by-nc/4.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
spellingShingle Research Articles
Jiang, Hao
Svensson, Oskar K. G.
Cao, Lili
Ryde, Ulf
Proton Transfer Pathways in Nitrogenase with and without Dissociated S2B
title Proton Transfer Pathways in Nitrogenase with and without Dissociated S2B
title_full Proton Transfer Pathways in Nitrogenase with and without Dissociated S2B
title_fullStr Proton Transfer Pathways in Nitrogenase with and without Dissociated S2B
title_full_unstemmed Proton Transfer Pathways in Nitrogenase with and without Dissociated S2B
title_short Proton Transfer Pathways in Nitrogenase with and without Dissociated S2B
title_sort proton transfer pathways in nitrogenase with and without dissociated s2b
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9804283/
https://www.ncbi.nlm.nih.gov/pubmed/35920055
http://dx.doi.org/10.1002/anie.202208544
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