title: Nitric oxide coupling to generate N2O promoted by a single-heme system as examined by density functional theory.
abstract: Bacteria utilize a heme/non-heme enzyme system to detoxify nitric oxide (NO) to N2O. In order to probe the capacity of a single-heme system to mediate this NO-to-N2O transformation, various scenarios for addition of electrons, protons, and a second NO molecule to a heme nitrosyl to generate N2O were explored by density functional theory calculations. We describe, utilizing this single-heme system, several stepwise intermediates along pathways that enable the critical N-N bond formation step yielding the desired Fe-N2O product. We also report a hitherto unreported directional second protonation that results in either productive N2O formation with loss of water, or formation of a non-productive hyponitrous acid adduct Fe{HONNOH}.
authors.affiliation: Department of Biological Engineering, Nanjing University of Science and Technology, 200 Xiao Ling Wei Road, Nanjing, Jiangsu Province, 210094, PR China; Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, 73019, USA. Electronic address: yijun@njust.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Yi
authors.affiliation: Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, 73019, USA.
authors.forename: Adam L O
authors.initials: ALO
authors.lastname: Campbell
authors.affiliation: Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, 73019, USA. Electronic address: grichteraddo@ou.edu.
authors.forename: George B
authors.initials: GB
authors.lastname: Richter-Addo
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D006418:Heme / Q000737:chemistry* / Q000378:metabolism; D007501:Iron / Q000737:chemistry; D008958:Models, Molecular; D009569:Nitric Oxide / Q000737:chemistry* / Q000378:metabolism*; D009573:Nitrites; D009609:Nitrous Oxide / Q000737:chemistry* / Q000378:metabolism*; D011166:Porphyrins / Q000737:chemistry / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D009573:Nitrites; D011166:Porphyrins; C025117:hyponitrite; C006969:chlorin; D009569:Nitric Oxide; D006418:Heme; C107018:porphine; D007501:Iron; D009609:Nitrous Oxide
keywords: Density functional theory; Hyponitrite; Iron porphine; Nitric oxide coupling; Nitrous oxide