Nitric oxide donation by the binuclear tetranitrosyl iron complexes in the presence of erythrocytes

Russian Chemical Bulletin - The kinetic regularities of nitric oxide donation in the presence of erythrocytes by representatives of a new class of synthetic nitric oxide donors, binuclear...     

Kinetic regularities of erythrocyte hemolysis and hemoglobin oxidation under the action of sulfur-nitrosyl iron complexes as nitric oxide donors

The kinetics of erythrocyte hemolysis and intra-erythrocyte hemoglobin oxidation under the action of synthetic sulfur-nitrosyl iron complexes was studied. The complexes capable of releasing nitric oxide due to spontaneous hydrolytic decomposition was studied. The addition of these complexes to a 0.2% suspension of mouse erythrocytes results in hemolysis. The kinetic curves of hemolysis exhibit an induction period, whose duration is different for each complex. The hemolysis is preceded by hemoglobin oxidation with nitric oxide penetrating into the cell. The oxidation of hemoglobin follows the first-order rate equation. The apparent first-order rate constants characterizing the NO-donating ability of each complex were determined. The hemolytic effect of the studied complexes is suggested to be related to the formation of peroxynitrite inside erythrocytes. Peroxynitrite is the cytotoxic product of interaction of nitric oxide and the superoxide radical anion.     

Reaction of ferricytochrome c with the iron nitrosyl complex {Fe2[S(CH2)2NH3]2(NO)4}SO4 • 2.5H2O

By an example of cysteamine iron nitrosyl complex {Fe₂[S(CH₂)₂NH₃]₂(NO)₄}SO₄ ? 2.5H₂O (CAC) it was shown for the first time that the NO donor hydrolysis in the presence of ferricytochrome c (cyt c³⁺) affords the iron nitrosyl complex NO—cyt c³⁺. It was found that cyt c³⁺ can serve as a depot for NO evolved during the hydrolysis of CAC. In the presence of CAC, the rate of NO—cyt c³⁺ complex decomposition to NO and cyt c³⁺ depends on the molar ratio [cyt c³⁺]: [CAC] and at [cyt c³⁺]: [CAC] = 0.3 it was found to be lower than that in decomposition of CAC in the absence of cyt c³⁺. As a result, the total NO evolving process becomes 5.6 times more prolonged. The number of NO groups evolved from CAC can be determined by the reaction of CAC with cyt c³⁺ in the presence of ferricyanide: at most one NO group is evolved to a solution in the spontaneous hydrolysis of CAC (pH 7.0), and no less than three of them are evolved from oxidized CAC.     

Effect of hemoglobin on the NO-donor ability of μ<Superscript>2</Superscript>-<Emphasis Type="Italic">S</Emphasis>-bis(pyrimidine-2-thiolato)tetranitrosyldiiron

The hydrolysis of the iron nitrosyl complex [Fe₂(μ₂-SC₄H₃N₂)₂(NO)₄](C₄H₃N₂S^? is pyrimidine-2-thiolate) in the presence of hemoglobin (Hb) is accompanied by the NO release into a solution. In the absence of Hb, the starting complex is oxidized by nitric oxide that is released into a solution, which leads to further transformations of NO, nitric oxide being present in the solution only partially. The effective rate constant for the decomposition of the complex is high and depends on its concentration. On the one hand, in the presence of Hb, NO molecules rapidly and irreversibly bind to Hb to form HbNO, which is the intermediate in the nitric oxide metabolism. On the other hand, the reversible binding of the iron nitrosyl complex to the surface functional groups of Hb leads to a decrease in its concentration in a solution and deceleration of the formation of NO. Therefore, Hb can ensure the complete and more prolonged assimilation of NO.     

Elliptic solutions of the semidiscrete B-version of the Kadomtsev–Petviashvili equation

Theoretical and Mathematical Physics - We study elliptic solutions of the semidiscrete B-version of the Kadomtsev–Petviashvili equation and derive the equations of motion of their poles. The...     

Investigation of the protective properties of a subnanometer diamond-like carbon film

The influence of diamond-like carbon coatings on the corrosion resistance of zirconium is investigated. Zirconium films with a thickness of 20 nm and different thicknesses of carbon protective films are examined. The chemical state of atoms on the surface is characterized using the measured photoelectron, electron energy loss, and Auger electron spectra. The results obtained demonstrate that the diamond-like carbon coating with a thickness of approximately 1 nm almost completely protects the metal film against oxidation. These protective properties of the diamond-like carbon coatings are explained by their high chemical inertness and uniformity over the thickness.