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Anatoly F Vanin

Publications and source records attributed to Anatoly F Vanin.

15 recordsLinked to original sources
PubMed2006

Protein-bound dinitrosyl-iron complexes appearing in blood of rabbit added with a low-molecular dinitrosyl-iron complex: EPR studies.

The formation of protein-bound dinitrosyl-iron complexes (DNIC) in blood plasma and packed red cell fraction has been demonstrated by the EPR method in the experiments on rabbits which were i/v injected with the low-molecular DNIC with thiosulphate. This formation was ensured by transfer of Fe(+)(NO(+))(2) moieties from low-molecular DNIC onto serum albumin or hemoglobin molecules. Protein-bound DNICs appeared immediately after low-molecular DNIC injection followed with gradually decreasing their amounts. The complexes could be detected by EPR technique during more than two days. The addition of water-soluble NO scavenger, the iron complex with N-methyl-d-glucamine dithiocarbamate (MGD) resulted in decomposition of a part of protein-bound DNICs and in effective excretion of secondary products (mainly mononitrosyl-iron complexes with MGD) from the blood flow.

Animals↗
PubMed2006

Dinitrosyl-iron complexes with thiol-containing ligands: spatial and electronic structures.

Parameters of the EPR signals of monomeric dinitrosyl-iron complexes with 1H-1,2,4-triazole-3-thiol (DNIC-MT), obtained by treating MT+ferrous iron in DMSO solution with gaseous NO, have been compared with those of the crystalline monomeric DNIC-MT with tetrahedral structure. Dissolved DNIC-MT were characterized by the isotropic EPR signal centered at g=2.03 with half-width of 0.7 mT and quintet hyperfine structure when recorded at ambient temperature or the anisotropic EPR signal with g( perpendicular)=2.045, g( parallel)=2.014 from frozen solution at 77 kappa, Cyrillic. DNIC-MT in crystalline state showed the structure-less symmetrical singlet EPR signal centered at g=2.03 and half-width of 1.7 mT at both room and liquid nitrogen temperature. The Lorentz shape of this signal indicates the strong exchange interaction between these complexes in the DNIC-MT crystal. Being dissolved in DMSO the crystalline sample of DNIC-MT demonstrated the EPR signal typical for DNIC-MT, obtained by treating MT+ferrous iron in DMSO solution with gaseous NO. Low spin (S=1/2) d(9) electron configuration of DNIC-MT with tetrahedral structure (formula [(MT-S(.))(2)Fe(-1)(NO(+))(2)](+)) was suggested to be responsible for the signal of DNIC-MT in crystalline state. Dissolving of the crystals of DNIC-MT may result in the change of their spatial and electronic structure, namely, tetrahedral structure of the complexes characterized by low spin d(9) electronic configuration transforms into a plane-square structure with d(7) electronic configuration and low spin S=1/2 state (formula [(MT- S(-))(2)Fe(+)(NO(+))(2)](+)). The latter was suggested to be characteristic of other DNICs with various thiol-containing ligands in the solutions. The proposed mechanism of these DNICs formation from ferrous iron, thiol and NO shows that the process could be accompanied by the ionization of NO molecules to NO(+) and NO(-) ions in the complexes. Detailed analysis of the shape of the EPR signals of these complexes provided additional information about the exchange interaction typical for DNIC-MT in crystals.

Electron Spin Resonance Spectroscopy↗
PubMed2006

Reduction enhances yields of nitric oxide trapping by iron-diethyldithiocarbamate complex in biological systems.

The mechanism of NO trapping by iron-diethylthiocarbamate complexes was investigated in cultured cells and animal and plant tissues. Contrary to common belief, the NO radicals are trapped by iron-diethylthiocarbamates not only in ferrous but in ferric state also in the biosystems. When DETC was excess over endogenous iron ligands like citrate, ferric DETC complexes were directly observed with EPR spectroscopy at g=4.3. This was the case when isolated spinach leaves, endothelial cultured cells were incubated in the medium with 2.5mM DETC or mouse liver was perfused with 100mM DETC solution. After trapping NO, the nitrosylated Fe-DETC adducts are mostly in diamagnetic ferric state, with only a minor fraction having been reduced to paramagnetic ferrous state by endogenous biological reductants. In actual in vivo trapping experiments with mice, the condition of excess DETC was not met. The substantial quantities of iron in animal tissues were bound to ligands other than DETC, in particular citrate. These non-DETC complexes appear as roughly equal mixtures of ferric and ferrous iron. The presence of NO favors the replacement of non-DETC ligands by DETC. In all biological systems considered here, the nitrosylated Fe-DETC adducts appear as mixture of diamagnetic and paramagnetic states. The diamagnetic ferric nitrosyl complexes may be reduced ex vivo to paramagnetic form by exogenous reductants like dithionite. The trapping yields are significantly enhanced upon exogenous reduction, as proven by NO trapping experiments in plants, cell cultures and mice.

Animals↗
PubMed2006

Why iron-dithiocarbamates ensure detection of nitric oxide in cells and tissues.

The in vivo mechanism of NO trapping by iron-dithiocarbamate complexes is considered. Contrary to common belief, we find that in biological systems the NO radicals are predominantly trapped by ferric iron-dithiocarbamates. Therefore, the trapping leads to ferric mononitrosyl complexes which are diamagnetic and cannot be directly detected with Electron Paramagnetic Resonance spectroscopy. The ferric mononitrosyl complexes are far easily reduced to ferrous state with L-cysteine, glutathione, ascorbate or dithiocarbamate ligands than their non-nitrosyl counterpart. When trapping NO in oxygenated biological systems, the majority of trapped nitric oxide is found in diamagnetic ferric mononitrosyl iron complexes. Only a minority fraction of NO is trapped in the form of paramagnetic ferrous mononitrosyl iron complexes with dithiocarbamate ligands. Subsequent ex vivo reduction of biological samples sharply increases the total yield of the paramagnetic mononitrosyl iron complexes. Reduction also eliminates the overlapping EPR spectrum from Cu(2+)-dithiocarbamate complexes. This facilitates the quantification of yields from NO trapping.

Animals↗
PubMed2005

Beneficial effect of gaseous nitric oxide on the healing of skin wounds.

Intermittent daily exposures (60 s) to NO-containing gas flow (NO dose of 500 ppm) generated by air-plasma unit "Plason" improves healing of skin wounds in rats. The gas flow treatment shortened the recovery time of both aseptic and purulent wounds (300 mm2 area) by nearly a third. The treatment allows to achieve a marked improvement in the histological, histochemical, and electron-microscopic characteristics of the affected tissue. The mechanism of this phenomenon was studied by spin trapping method. The NO status of the wound tissue was investigated with EPR by following the formation of paramagnetic mononitrosyl complexes with iron-diethyldithiocarbamate, or with the heme groups in hemoglobin or myoglobin. For the first 5 min after a gas treatment with the exposure of 60s, detectable NO levels in the affected tissue were slightly lowered with respect to untreated controls. At subsequent times, treated tissues showed the formation of large quantities of nitroso-iron complexes: At 30-40 min after gas exposure, their levels were nearly two orders of magnitude higher than soon after (15 s-5 min) the exposure. The data demonstrate that the accumulation of nitrosyl-iron complexes reflects a sharp rise in endogenous NO production inside the affected tissue. Paradoxically, the beneficial effect of gaseous NO treatment can be mediated by the formation of limited quantities of peroxynitrite due to the reaction between exogenous NO and superoxide anions generated in high amount in wound tissue. This peroxynitrite has a strong prooxidant effect and can activate various antioxidant systems which diminish the amount of superoxide anions in wound tissue. The reduced superoxide levels allow to increase the contents of endogenous NO in gas-treated tissues. Therefore, the beneficial action of the treatment is attributed to enhanced NO bioavailability.

Animals↗
PubMed2004

Endogenous superoxide production and the nitrite/nitrate ratio control the concentration of bioavailable free nitric oxide in leaves.

We have quantitatively measured nitric oxide production in the leaves of Arabidopsis thaliana and Vicia faba by adapting ferrous dithiocarbamate spin tapping methods previously used in animal systems. Hydrophobic diethyldithiocarbamate complexes were used to measure NO interacting with membranes, and hydrophilic N-methyl-d-glucamine dithiocarbamate was used to measure NO released into the external solution. Both complexes were able to trap levels of NO, readily detectable by EPR spectroscopy. Basal rates of NO production (in the order of 1 nmol g(-) (1) h(-1)) agreed with previous studies. However, use of methodologies that corrected for the removal of free NO by endogenously produced superoxide resulted in a significant increase in trapped NO (up to 18 nmol g(-) (1) h(-1)). Basal NO production in leaves is therefore much higher than previously thought, but this is masked by significant superoxide production. The effects of nitrite (increased rate) and nitrate (decreased rate) are consistent with a role for nitrate reductase as the source of this basal NO production. However, rates under physiologically achievable nitrite concentrations never approach that reported following pathogen induction of plant nitric-oxide synthase. In Hibiscus rosa sinensis, the addition of exogenous nitrite generated sufficient NO such that EPR could be used to detect its production using endogenous spin traps (forming paramagnetic dinitrosyl iron complexes). Indeed the levels of this nitrosylated iron pool are sufficiently high that they may represent a method of maintaining bioavailable iron levels under conditions of iron starvation, thus explaining the previously observed role of NO in preventing chlorosis under these conditions.

Arabidopsis↗
PubMed2004

The mechanisms of S-nitrosothiol decomposition catalyzed by iron.

The mechanisms of S-nitrosothiol transformation into paramagnetic dinitrosyl iron complexes (DNICs) with thiol- or non-thiol ligands or mononitrosyl iron complex (MNICs) with N-methyl-D-glucamine dithiocarbamate catalyzed by iron(II) ions under anaerobic conditions were studied by monitoring EPR or optical features of the complexes and S-nitrosothiols. The kinetic investigations demonstrated the appearance of short-living paramagnetic mononitrosyl-iron complex with L-cysteine prior to the formation of stable dinitrosyl-iron complex with cysteine in the solution of iron(II)-citrate complex (50-100 microM), S-nitrosocysteine (400 microM), and L-cysteine (20 mM) in 100 mM Hepes buffer (pH 7.4). The addition of deoxyhemoglobin (100 microM) did not influence the process, which points to a direct interaction between S-nitrosocysteine and iron(II) ions to yield DNIC. The reaction of DNIC-cysteine formation is first- and second-order in iron and S-nitrosocysteine, respectively. The third-order rate constant is (1.0 +/- 0.2) x 10(5) M(-2) s(-1) (estimated from EPR results) or (2.0 +/- 0.1) x 10(4) M(-2) s(-1) (estimated by optical method). A similar process of DNIC-cysteine formation was observed in a solution of iron(II)-citrate complex, L-cysteine, and NO-proline (200 microM) as a NO* donor. The appearance of a less stable dinitrosyl-iron complex with phosphate was detected when solutions of iron(II)-citrate containing 100 mM phosphate buffer (pH 7.4) were mixed with S-nitrosocysteine or NO-proline. The rapid formation of DNIC with phosphate was followed by its decay. When the concentration of L-cysteine in solutions was reduced from 20 to 1 mM, the life-time of the DNIC-cysteine diminished notably; this was caused by consumption of L-cysteine in the process of DNIC-cysteine formation from S-nitrosocysteine and iron. Thus, L-cysteine is consumed. Formation of DNIC with glutathione was also observed in a solution of glutathione (20 mM), S-nitrosoglutathione (400 microM), and iron(II) complex (800 microM) in 100 mM Hepes buffer (pH 7.4), but the rate of formation was about 10 times slower than the formation of the DNIC-cysteine. The rate of MNIC-MGD formation from iron(II)-MGD complexes and S-nitrosocysteine was first-order in both reactants. The second-order rate constant for this reaction, estimated from EPR measurements, was 30 +/- 5 M(-1) s(-1). Rate constants of MNIC-MGD formation from iron(II)-MGD and the more stable S-nitrosoglutathione and S-nitroso-D,L-penicillamine were equal to 3.0 +/- 0.3 and 0.3 +/- 0.05 M(-1) s(-1), respectively. Thus, the concerted mechanism of DNIC and MNIC formation from S-nitrosothiols and iron(II) ions can be suggested to be predominant.

Catalysis↗
PubMed2003

Inhibition of arterial contraction by dinitrosyl-iron complexes: critical role of the thiol ligand in determining rate of nitric oxide (NO) release and formation of releasable NO stores by S-nitrosation.

The inhibition of arterial tone produced by two nitric oxide (NO) derivatives of biological relevance, dinitrosyl-iron complexes with cysteine (DNIC-CYS) or with glutathione (DNIC-GSH), was compared. Both compounds induced vasorelaxation within the same concentration range (3-300 nM) in endothelium-denuded rat aortic rings. Consistent with a faster rate of NO release from DNIC-CYS than from DNIC-GSH, the relaxant effect of DNIC-CYS was rapid in onset and tended to recover with time, whereas the one of DNIC-GSH developed slowly and was sustained. In addition, DNIC-GSH (0.3 and 1 microM) but not DNIC-CYS (1 microM) induced, even after washout of the drug, a persistent hyporesponsiveness to vasoconstrictors and a relaxant effect of low molecular weight thiols like N-acetylcysteine (NAC, which can displace NO from preformed NO stores). Both effects of DNIC-GSH were associated with elevation of cyclic GMP content and were attenuated by NO scavengers or a cyclic GMP-dependent protein kinases inhibitor. In rings previously exposed to DNIC-GSH, addition of mercuric chloride (which can cleave the cysteine-NO bond of S-nitrosothiols) elicited relaxation, completely blunted the one of NAC and also abolished the persistent elevation of NO content. In conclusion, this study shows that whereas both DNIC-CYS and DNIC-GSH elicited a NO release-associated relaxant effect in isolated arteries, only DNIC-GSH induced an inhibition of contraction which persisted after drug removal. The persistent effect of DNIC-GSH was attributed to the formation of releasable NO stores in arterial tissue, most probably as S-nitrosothiols. Thus, the nature of the thiol ligand plays a critical role in determining the mechanisms and duration of the effect of LMW-DNIC in arteries.

Acetylcysteine↗
PubMed2003

Activation of soluble guanylate cyclase by NO donors--S-nitrosothiols, and dinitrosyl-iron complexes with thiol-containing ligands.

We studied the capability of dimeric forms of dinitrosyl-iron complexes and S-nitrosothiols to activate soluble guanylate cyclase (sGC) from human platelet cytosol. The dinitrosyl-iron complexes had the ligands glutathione (DNIC-GS) or N-acetylcysteine (DNIC-NAC). The S-nitrosothiols were S-nitrosoglutathione (GS-NO) or S-nitrosoacetylcysteine (SNAC). For both glutathione and N-acetylcysteine, the DNIC and S-nitrosothiol forms are equally effective activators of sGC. The activation mechanism is strongly affected by the presence of intrinsic metal ions. Pretreatment with the potent iron chelator, disodium salt of bathophenanthroline disulfonic acid (BPDS), suppressed sGC activation by GS-NO: the concentration of GS-NO producing maximal sGC activation was increased by two orders of magnitude. In contrast, activation by DNIC-GS is strongly enhanced by BPDS. When BPDS was added 10 min after supplementation of DNIC-GS or GS-NO at 4 degrees C, it exerted a similar effect on sGC activation by either NO donor: BPDS only enhanced the sGC stimulation at low concentrations of the NO donors. Our experiments demonstrated that both Fe(2+) and Cu(2+) ions contribute to the decomposition of GS-NO in the presence of ascorbate. The decomposition of GS-NO induced by Fe(2+) ions was accompanied by formation of DNIC. BPDS protected GS-NO against the destructive action of Fe(2+) but not Cu(2+) ions. Additionally, BPDS is a sufficiently strong chelator to remove the iron from DNIC-GS complexes. Based on our data, we propose that S-nitrosothiols activate sGC via a two-step iron-mediated process: In the first step, intrinsic Fe(2+) ions catalyze the formation of DNICs from S-nitrosothiols. In the secondary step, these newly formed DNICs act as the real NO donors responsible for sGC activation.

Acetylcysteine↗
PubMed2002

Exogenous ferrous iron is required for the nitric oxide-catalysed destruction of the iron-sulphur centre in adrenodoxin.

No effects of gaseous NO added at a pressure of 19.95 kPa on the stability of the binuclear iron-sulphur centre (ISC) of reduced iron-sulphur protein adrenodoxin (0.2 mM) have been observed using the EPR method. However, the incubation of the protein with NO in the presence of ferrous iron (1.8 mM) led to complete ISC degradation, accompanied by the formation of protein-bound dinitrosyl iron complexes (DNICs; 0.3+/-0.1 mM). Similar results were obtained when low-molecular-mass DNIC with phosphate or cysteine (1.8 mM) were added to solutions of pre-reduced adrenodoxin. The degradation of the ISC was suggested to be due to the attack of the Fe(+)(NO(+))(2) group from low-molecular-mass DNICs added or formed during the interaction between NO and ferrous ions on the thiol groups in active centres of adrenodoxin. This attack leads to a release of endogenous iron from the centres, which is capable of forming both low-molecular-mass and protein-bound DNIC, thereby ensuring further ISC degradation.

Adrenodoxin↗
PubMed2002

Anti-inflammatory effects of tetrahydrobiopterin on early rejection in renal allografts: modulation of inducible nitric oxide synthase.

Oxidative stress contributes to the development of early transplant failure. As nitric oxide synthases (NOS) can act as sources of superoxide, we investigated the effect of the NOS cofactor tetrahydrobiopterin (BH4) on oxyradical production and early rejection in a rat kidney transplantation model. Allograft transplantation (Brown Norway to Lewis) showed more renal superoxide production and monocyte infiltration when compared with isografts (Lewis to Lewis). Administration of the stable BH4 precursor sepiapterin had no effect on superoxide production in the isografts (51+/-10 vs. 69+/-17 cps/10 mg protein), but led to a marked decrease in superoxide production in the allografts (116+/-11 vs. 60+/-6 cps/10 mg protein; P<0.05) and was accompanied by a reduction in periarterial macrophage infiltration (3.3+/-0.7 vs. 1.3+/-0.3 cells/vessel; P<0.05) and an increase in NO production (78+/-22 vs. 173+/-12 AU/g kidney) (P<0.01). In vitro experiments confirm that iNOS can produce superoxide mainly from the heme domain, whereas BH4 administration can reverse this superoxide production in the presence of adequate anti-oxidant defense. Our findings support the hypothesis that BH4 can be used to modulate the function of the inflammatory iNOS isoform and suggest a potential therapeutic role for sepiapterin in early allograft rejection.

Animals↗
PubMed2002

In vivo nitric oxide transfer of a physiological NO carrier, dinitrosyl dithiolato iron complex, to target complex.

Dinitrosyl dithiolato iron complex (DNIC) has been identified as an endogenous NO carrier, yet in vivo mechanisms of NO donation remain undefined. Transnitrosylation, in which a coordinated NO group is transferred to another metal complex, has been observed in transition-metal-nitrosyl chemistry. In this study, we used three kinds of iron dithiocarbamate complexes (Fe-DTCs) as NO acceptors to elucidate in vivo transnitrosylation of diglutathionyl dinitrosyl iron complex [DNIC-(GS)(2)]. Fe-DTCs were administered to mice after the injection of DNIC-(GS)(2) and electron paramagnetic resonance (EPR) spectra were measured both in the resected organs and in the upper abdomen of living mice. The spectral feature gradually changed from an initial DNIC-(GS)(2) signal to mononitrosyl iron dithiocarbamate one, suggesting that NO-Fe-DTC was formed through in vivo reaction of DNIC-(GS)(2) with Fe-DTC. The spectral results in in vitro and in vivo systems indicate that NO-Fe-DTCs can be formed not only by the transfer of coordinated NO-group(s) in DNIC-(GS)(2) but also by the abstraction of Fe-NO group in DNIC-(GS)(2) by free DTC ligands. Transnitrosylation proceeded more rapidly in blood than in liver and kidney; and more efficiently in kidney than in liver. Further, the ability to accept NO from DNIC was dependent on water-solubility of Fe-DTCs. Thus, in vivo transnitrosylation from DNIC to exogenous iron complex could be observed and this reaction was influenced by biological constituents and properties of iron complex. These results demonstrate that the transnitrosylation from DNIC to intrinsic NO acceptors like metalloproteins has a probable significance in in vivo NO transfer process.

Animals↗
PubMed2002

Evidence that intrinsic iron but not intrinsic copper determines S-nitrosocysteine decomposition in buffer solution.

The present experiments were designed to analyze the influence of copper and iron ions on the process of decomposition of S-nitrosocysteine (cysNO), the most labile species among S-nitrosothiols (RSNO). CysNO fate in buffer solution was evaluated by optical and electron paramagnetic resonance (EPR) spectroscopy, and the consequences on its vasorelaxant effect were studied on noradrenaline-precontracted rat aortic rings. The main results are the following: (i) copper or iron ions, especially in the presence of the reducing agent ascorbate, accelerated the decomposition of cysNO and markedly attenuated the amplitude and duration of the relaxant effect of cysNO; (ii) by contrast, the iron and copper chelators bathophenantroline disulfonic acid (BPDS) and bathocuproine disulfonic acid (BCS) exerted a stabilizing effect on cysNO, prolonged its vasorelaxant effect, and abolished the influence of ascorbate; (iii) in the presence of ascorbate, BPDS displayed a selective inhibitory effect toward the influence of iron ions (but not toward copper ions) on cysNO decomposition and vasorelaxant effect, while BCS prevented the effects of both copper and iron ions; (iv) L-cysteine enhanced stability and prolonged the relaxant effect of cysNO; (v) the process of iron-induced decomposition of cysNO was associated with the formation of EPR-detectable dinitrosyl-iron complexes (DNIC) either with non-thiol- or thiol-containing ligands (depending on the presence of L-cysteine), both of which exhibiting vasorelaxant properties. From these data, it is concluded that the amount of intrinsic copper was probably too low to produce a destabilizing effect even on the most labile RSNO, cysNO, and that only intrinsic iron, through the formation of DNIC, was responsible for the process of cysNO decomposition and thus influenced its vasorelaxant properties.

Animals↗