title: Nitric oxide initiates iron binding to neocuproine.
abstract: It was demonstrated that two species of paramagnetic dinitrosyl iron complex (DNIC) with neocuproine form under the following conditions: in addition of neocuproine to a solution of DNIC with phosphate; in gaseous NO treatment of a mixture of Fe(2+) + neocuproine aqueous solutions at pH 6.5-8; and in addition of Fe(2+)--citrate complex + neocuproine to a S-nitrosocysteine (cys-NO) solution. The first form of DNIC with neocuproine is characterized by an EPR signal with g-factor values of 2.087, 2.055, and 2.025, when it is recorded at 77K. At room temperature, the complex displays a symmetric singlet at g = 2.05. The second form of DNIC with neocuproine gives an EPR signal with g-factor values of 2.042, 2.02, and 2.003, which can be recorded at a low temperature only.The revealed complexes are close to DNIC with cysteine in their stability. The ability of neocuproine to bind Fe(2+) in the presence of NO with formation of paramagnetic DNICs warrants critical reevaluation of the statement that neocuproine is only able to bind Cu(+) ions. It was suggested that the observed affinity of neocuproine to iron was due to transition of Fe(2+) in DNIC with neocuproine to Fe(+). In experiments on cys-NO, it was shown that the stabilizing effect of neocuproine on this compound could be due to neocuproine binding to the iron catalyzing decomposition of cys-NO.
authors: Institute of Chemical Physics, Russian Academy of Sciences, Kosygin Strasse 4, Moscow, 11797, Russian Federation. mikoyan@center.chph.ras.ru
authors: A F
authors: AF
authors: Vanin
authors: V A
authors: VA
authors: Serezhenkov
authors: I V
authors: IV
authors: Malenkova
mesh_terms: D002614:Chelating Agents / Q000378:metabolism*; D003545:Cysteine / Q000031:analogs & derivatives / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D007502:Iron Chelating Agents / Q000378:metabolism; D007700:Kinetics; D009569:Nitric Oxide / Q000378:metabolism*; D009589:Nitrogen Oxides / Q000737:chemistry / Q000378:metabolism*; D009603:Nitroso Compounds / Q000378:metabolism; D010618:Phenanthrolines / Q000378:metabolism*; D026403:S-Nitrosothiols; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
chemical_list: D002614:Chelating Agents; D007502:Iron Chelating Agents; D009589:Nitrogen Oxides; D009603:Nitroso Compounds; D010618:Phenanthrolines; D026403:S-Nitrosothiols; D009569:Nitric Oxide; C073661:dinitrosyl iron complex; C002701:neocuproine; C021315:S-nitrosocysteine; D007501:Iron; D003545:Cysteine