Redox properties of iron-dithiocarbamates and their nitrosyl derivatives: implications for their use as traps of nitric oxide in biological systems.

While the Fe(2+)-dithiocarbamate complexes have been commonly used as NO traps to estimate NO production in biological systems, these complexes can undergo complex redox chemistry. Characterization of this redox chemistry is of critical importance for the use of this method as a quantitative assay of NO generation. We observe that the commonly used Fe(2+) complexes of N-methyl-D-glucamine dithiocarbamate (MGD) or diethyldithiocarbamate (DETC) are rapidly oxidized under aerobic conditions to form Fe(3+) complexes.

Complexes of Fe2+ with diethyldithiocarbamate or N-methyl-D-glucamine dithiocarbamate as traps of nitric oxide in animal tissues: comparative investigations.

In EPR experiments on mice it was demonstrated that a hydrophobic complex Fe2+ with diethyldithiocarbamate (DETC) is a more efficient selective NO trap than a hydrophilic complex Fe2+ with N-methyl-D-glutamine dithiocarbamate (MGD). This difference can be due to the higher stability of paramagnetic nitrosyl iron complex with DETC (MNIC-DETC) formed by NO binding to Fe2+-DETC in animal tissues in vivo. The complex analogue MNIC-MGD is reversibly oxidized in animal blood to transform into the diamagnetic EPR-silent form.

[Hydrophobic and hydrophilic complexes of Fe2+ with dithiocarbamate derivatives as a nitric oxide trap in mice].

It has been shown by using EPR method that hydrophobic complexes Fe(2+)-diethyldithiocarbamate (DETC) act more efficiently as a selective traps of nitric oxide (NO) in mice organisms than hydrophilic complexes Fe(2+)-N-methyl-D-glutamyldithiocarbamate (MGD). This difference seemed to be due to higher stability of paramagnetic mononitrosyl iron complexes with DETC (MNIC-DETC) formed in vivo in animal tissues in a result of NO binding with Fe(2+)-DETC complexes. Analogous complexes MNIC-MGD appeared a blood were oxidized to diamagnetic, EPR silent form.

[Dimeric and monomeric forms of dinitrosyl iron complexes with thiol-containing ligands: physico-chemical properties and vasodilator activity].

When studying the vasodilator activity of dinitrosyl iron complexes (DNIC) with thiol-containing ligands as NO donors, it should be taken into consideration that these complexes depending on the content of thiols in the environment can occur in either form that differ by their EPR, gamma-resonance and optical characteristics and also by their vasodilator effect on isolated blood vessels. The more stable diamagnetic form appears at the ratio Fe2+:RS(-)-1:2. It reversibly dissociates to the monomeric paramagnetic form [(RS-)2Fe+(NO+)2] on increasing the thiol content to the level 20 times and more exceeding the quantity of iron.

Physical properties of dinitrosyl iron complexes with thiol-containing ligands in relation with their vasodilator activity.

When studying the vasodilator activity of dinitrosyl iron complexes (DNIC) with thiol-containing ligands as NO donors, it should be taken into consideration that these complexes depending on the content of thiols in the environment can occur in either of two forms that differ by their EPR, gamma-resonance and optical characteristics and also by their vasodilator effect on isolated blood vessels. The more stable diamagnetic form appears at the ratio Fe2+:RS- = 1:2. It reversibly dissociates to the monomeric paramagnetic form [(RS-)2Fe+(NO+)2] on increasing the thiol content to the level 20-times and more exceeding the quantity of iron.

Mössbauer spectroscopy of oxygenated haemoglobins.

Murine tetrameric oxyhaemoglobin and insect monomeric erythrocruorin were studied. A doublet with the Lorentz form of lines (delta EQ = 2.22 mm s-1; delta alpha-Fe = 0.

[Study of the binding of iron ions by melanoprotein granules of the eye pigment epithelium using gamma-resonance spectroscopy].

Interaction between Fe2+ ions and melanoproteid granules (MPG) of bovine eye pigment epithelium was studied by gammaresonance spectroscopy. MPG was found to form complexes with bi- and three-valent ferrum ions. MPG can both directly bind Fe2+ ions and oxidize them Fe3+ inactive in prooxidant state and bind the latter.

[Study of the relaxation of nonequilibrium hemoglobin states by Mössbauer spectroscopy].

Nonequilibrium hemoglobin states formed at low-temperature (T = 77K) reduction of its derivatives (MetHb and HbO2) by thermolysed electrons have been studied by Mössbauer spectroscopy. Relaxation of nonequilibrium states at the samples heating was observed. Correlation between the relaxation temperatures and the changes of protein dynamic structure determined from Mössbauer data were stated.

[Ratio between free and deposited iron in animal tissues].

When mice were given water diet with 57Fe a practically complete exchange in the blood 56Fe and 57Fe was observed during 2 months. 57Fe isotope was accumulated in iron storage of the liver, kidney and spleen. Partial isotope exchange for free iron occurred in these tissues too.

[Gamma-resonance spectrometry study of the nonequilibrium states of hemoglobin].

Reduction of frozen water-glycerol solutions of methemoglobin by thermolysed electrons at 77 degrees K has been studied by Mossbauer spectroscopy. The formation of nonequilibrium hemoglobin states with two slightly different low-spin ferroforms was observed. The latter is explained by the presence of two ferroforms in initial methemoglobin.

[Study of the dynamics of water-protein systems by the technic of gamma-resonance spectroscopy].

The possibility of using gamma resonance spectroscopy (GRS) for studying the dynamics of water-protein systems is shown in the present work. The experiments were carried out on an albumin-water system. The results obtained are compared with those obtained by the spin label method under the same conditions.