title: Transformation of dinitrosyl iron complexes [(NO)2Fe(SR)2]- (R = Et, Ph) into [4Fe-4S] Clusters [Fe4S4(SPh)4]2-: relevance to the repair of the nitric oxide-modified ferredoxin [4Fe-4S] clusters.
abstract: Transformation of dinitrosyl iron complexes (DNICs) [(NO)(2)Fe(SR)(2)](-) (R = Et, Ph) into [4Fe-4S] clusters [Fe(4)S(4)(SPh)(4)](2-) in the presence of [Fe(SPh)(4)](2-/1-) and S-donor species S(8) via the reassembling process ([(NO)(2)Fe(SR)(2)](-) --> [Fe(4)S(3)(NO)(7)](-) (1)/[Fe(4)S(3)(NO)(7)](2-) (2) --> [Fe(4)S(4)(NO)(4)](2-) (3) --> [Fe(4)S(4)(SPh)(4)](2-) (5)) was demonstrated. Reaction of [(NO)(2)Fe(SR)(2)](-) (R = Et, Ph) with S(8) in THF, followed by the addition of HBF(4) into the mixture solution, yielded complex [Fe(4)S(3)(NO)(7)](-) (1). Complex [Fe(4)S(3)(NO)(7)](2-) (2), obtained from reduction of complex 1 by [Na][biphenyl], was converted into complex [Fe(4)S(4)(NO)(4)](2-) (3) along with byproduct [(NO)(2)Fe(SR)(2)](-) via the proposed [Fe(4)S(3)(SPh)(NO)(4)](2-) intermediate upon treating complex 2 with 1.5 equiv of [Fe(SPh)(4)](2-) and the subsequent addition of 1/8 equiv of S(8) in CH(3)CN at ambient temperature. Complex 3 was characterized by IR, UV-vis, and single-crystal X-ray diffraction. Upon addition of complex 3 to the CH(3)CN solution of [Fe(SPh)(4)](-) in a 1:2 molar ratio at ambient temperature, the rapid NO radical-thiyl radical exchange reaction between complex 3 and the biomimetic oxidized form of rubredoxin [Fe(SPh)(4)](-) occurred, leading to the simultaneous formation of [4Fe-4S] cluster [Fe(4)S(4)(SPh)(4)](2-) (5) and DNIC [(NO)(2)Fe(SPh)(2)](-). This result demonstrates a successful biomimetic reassembly of [4Fe-4S] cluster [Fe(4)S(4)(SPh)(4)](2-) from NO-modified [Fe-S] clusters, relevant to the repair of DNICs derived from nitrosylation of [4Fe-4S] clusters of endonuclease III back to [4Fe-4S] clusters upon addition of ferrous ion, cysteine, and IscS.
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan, Republic of China.
authors.forename: Chih-Chin
authors.initials: CC
authors.lastname: Tsou
authors.forename: Zong-Sian
authors.initials: ZS
authors.lastname: Lin
authors.forename: Tsai-Te
authors.initials: TT
authors.lastname: Lu
authors.forename: Wen-Feng
authors.initials: WF
authors.lastname: Liaw
mesh_terms: D018360:Crystallography, X-Ray; D005288:Ferredoxins / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D058085:Iron Compounds / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009569:Nitric Oxide / Q000737:chemistry*; D009589:Nitrogen Oxides / Q000737:chemistry*; D013457:Sulfur Compounds / Q000737:chemistry*
chemical_list: D005288:Ferredoxins; D058085:Iron Compounds; D009589:Nitrogen Oxides; D013457:Sulfur Compounds; D009569:Nitric Oxide; C073661:dinitrosyl iron complex; D007501:Iron