title: Iron(II) porphyrins induced conversion of nitrite into nitric oxide: A computational study.
abstract: Nitrite reduction to nitric oxide by heme proteins was reported as a protective mechanism to hypoxic injury in mammalian physiology. In this study, the pathways of nitrite reduction to nitric oxide mediated by iron(II) porphyrin (P) complexes, which were generally recognized as models for heme proteins, were investigated by using density functional theory (DFT). In view of two type isomers of combination of nitrite and Fe(II)(P), N-nitro- and O-nitrito-Fe(II)-porphyrin complexes, and two binding sites of proton to the different O atoms of nitrite moiety, four main pathways for the conversion of nitrite into nitric oxide mediated by iron(II) porphyrins were proposed. The results indicate that the pathway of N-bound Fe(II)(P)(NO2) isomer into Fe(III)(P)(NO) and water is similar to that of O-bound isomer into nitric oxide and Fe(III)(P)(OH) in both thermodynamical and dynamical aspects. Based on the initial computational studies of five-coordinate nitrite complexes, the conversion of nitrite into NO mediated by Fe(II)(P)(L) complexes with 14 kinds of proximal ligands was also investigated. Generally, the same conclusion that the pathways of N-bound isomers are similar to those of O-bound isomer was obtained for iron(II) porphyrin with ligands. Different effects of ligands on the reduction reactions were also found. It is notable that the negative proximal ligands can improve reactive abilities of N-nitro-iron(II) porphyrins in the conversion of nitrite into nitric oxide compared to neutral ligands. The findings will be helpful to expand our understanding of the mechanism of nitrite reduction to nitric oxide by iron(II) porphyrins.
authors.affiliation: College of Life Science & Bioengineering, Beijing University of Technology, Beijing 100124, PR China.
authors.forename: Ting Ting
authors.initials: TT
authors.lastname: Zhang
authors.affiliation: College of Life Science & Bioengineering, Beijing University of Technology, Beijing 100124, PR China. Electronic address: ydliu@bjut.edu.cn.
authors.forename: Yong Dong
authors.initials: YD
authors.lastname: Liu
authors.affiliation: College of Life Science & Bioengineering, Beijing University of Technology, Beijing 100124, PR China.
authors.forename: Ru Gang
authors.initials: RG
authors.lastname: Zhong
mesh_terms: D006639:Histidine / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D007536:Isomerism; D008024:Ligands; D008665:Metalloporphyrins / Q000737:chemistry*; D008956:Models, Chemical; D009569:Nitric Oxide / Q000737:chemistry*; D009573:Nitrites / Q000737:chemistry*; D010084:Oxidation-Reduction; D011522:Protons; D014867:Water / Q000737:chemistry
chemical_list: D008024:Ligands; D008665:Metalloporphyrins; D009573:Nitrites; D011522:Protons; C513578:porphyrinatoiron(II); D014867:Water; D009569:Nitric Oxide; D006639:Histidine; D007501:Iron
keywords: DFT; Iron(II) porphyrin; Nitric oxide; Nitrite; Proximal ligand