Heme-copper assembly mediated reductive coupling of nitrogen monoxide (*NO).
A iron-dinitrosyl species ((6)L)Fe(NO)(2) (2), generated from nitrogen monoxide (*NO) binding to its related iron(II)-mononitrosyl complex ((6)L)Fe(NO) (1), efficiently effects reductive coupling of two *NO molecules to release nitrous oxide (N(2)O), when Cu(+) ion and 2 equiv acid are added; the heme/Cu product is [((6)L)Fe(III)...Cu(II)(D)](3+) (D = H(2)O or MeCN). In a control experiment where only ((6)L)Fe(NO)(2) (2) is exposed to 2 equiv acid, no UV-vis change is observed; upon warming, *NO((g)) is released and ((6)L)Fe(NO) is reformed. The copper ion complex within the (6)L ligand framework is required for the *NO coupling chemistry. In a further control experiment Cu(+) ion is added to ((6)L)Fe(NO)(2) without acid present, [((6)L)Fe(NO)...Cu(II)(NO(2)(-))](+) is obtained, with the amount of N(2)O((g)) released fitting with copper(I) ion promoted disproportionation chemistry, 3*NO + ligand-Cu(I) --> N(2)O + ligand-Cu(II)(NO(2)(-)). The chemical system described represents a (stoichiometric) functional model for heme/Cu protein nitric oxide reductase activity.
Wang
Jun
J
Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Schopfer
Mark P
MP
Sarjeant
Amy A N
AA
Karlin
Kenneth D
KD
D003300:Copper / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D006418:Heme / Q000737:chemistry*; D009569:Nitric Oxide / Q000737:chemistry*; D009573:Nitrites / Q000737:chemistry; D009585:Nitrogen Dioxide / Q000737:chemistry; D010084:Oxidation-Reduction
D005290:Ferric Compounds; D009573:Nitrites; C025117:hyponitrite; D009569:Nitric Oxide; D006418:Heme; D003300:Copper; D009585:Nitrogen Dioxide