caa a22 4500 605513120 CHVBK 20210128100658.0 cr unu---uuuuu 210128e20150501xx s 000 0 eng 10.1007/s00894-015-2679-0 doi (NATIONALLICENCE)springer-10.1007/s00894-015-2679-0 Bacterial nitric oxide reductase: a mechanism revisited by an ONIOM (DFT:MM) study [Elektronische Daten] [Amr Attia, Radu Silaghi-Dumitrescu] Bacterial nitric oxide reductase (cNOR) is an important binuclear iron enzyme responsible for the reduction of nitric oxide to nitrous oxide in the catalytic cycle of bacterial respiration. The reaction mechanism of cNOR as well as the key reactive intermediates of the reaction are still under debate. Here, we report a computational study based on ONIOM (DFT:MM) calculations aimed at investigating the reaction mechanism of cNOR. The results suggest that the reaction proceeds via the mono-nitrosyl mechanism which starts off by the binding of an NO molecule to the heme b3 center, N-N hyponitrite bond formation as a result of the reaction with a second NO molecule was found to proceed with an exothermic energy barrier to yield a hyponitrite adduct forming an open (incomplete) ring conformation with the non-heme FeB center (O-N-N-O-FeB). N-O bond cleavage to yield N2O was shown to be the rate-limiting step with an activation barrier of 22.6kcal mol-1. The dinitrosyl (trans) mechanism, previously proposed by several studies, was also examined and found unfavorable due to high activation barriers of the resulting intermediates. Graphical Abstract Bacterial nitric oxide reductaseᅟ Springer-Verlag Berlin Heidelberg, 2015 Bacterial nitric oxide reductase nationallicence cNOR nationallicence DFT nationallicence ONIOM nationallicence QM:MM nationallicence Reaction mechanism nationallicence Heme iron nationallicence Non-heme iron nationallicence Attia Amr Department of Chemistry, Faculty of Chemistry and Chemical Engineering, Babeș-Bolyai University, Cluj-Napoca, Romania aut Silaghi-Dumitrescu Radu Department of Chemistry, Faculty of Chemistry and Chemical Engineering, Babeș-Bolyai University, Cluj-Napoca, Romania aut Journal of Molecular Modeling Springer Berlin Heidelberg 21/5(2015-05-01), 1-12 1610-2940 21:5<1 2015 21 894 https://doi.org/10.1007/s00894-015-2679-0 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00894-015-2679-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Attia Amr Department of Chemistry, Faculty of Chemistry and Chemical Engineering, Babeș-Bolyai University, Cluj-Napoca, Romania aut NATIONALLICENCE 700 1- Silaghi-Dumitrescu Radu Department of Chemistry, Faculty of Chemistry and Chemical Engineering, Babeș-Bolyai University, Cluj-Napoca, Romania aut NATIONALLICENCE 773 0- Journal of Molecular Modeling Springer Berlin Heidelberg 21/5(2015-05-01), 1-12 1610-2940 21:5<1 2015 21 894