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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have shown that peroxynitrite (ONOO-) inhibits streptokinase-induced conversion of plasminogen to plasmin in a concentration-dependent manner and reduces both amidolytic (IC5o approximately 280 microM at 10 microM concentration of enzyme) and proteolytic activity of plasmin. Spectrophotometric and immunoblot analysis of peroxynitrite-treated plasminogen demonstrates a concentration-dependent increase in its nitrotyrosine residues that correlates with a decreased generation of active plasmin. Peroxynitrite (1 mM) causes the nitration of 2.9 tyrosines per plasminogen molecule. Glutathione, like deferoxamine, partially protects plasminogen from peroxynitrite-induced inactivation and reduces the extent of tyrosine nitration. These data suggest that nitration of plasminogen tyrosine residues by peroxynitrite might play an important role in the inhibition of plasmin catalytic activity.
Mol Cell Biochem 2004 Dec
PMID:Peroxynitrite and fibrinolytic system: the effect of peroxynitrite on plasmin activity. 1566 95

The synthesis and characterization of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pd(II) and UO2(II) chelates of 1-(2-thiazolylazo)-2-naphthalenol (TAN) were reported. The dissociation constants of the ligand and the stability constants of the metal complexes were calculated pH-metrically at 25 degrees C and 0.1 M ionic strength. The solid complexes were characterized by elemental and thermal analyses, molar conductance, IR, magnetic and diffuse reflectance spectra. The complexes were found to have the formulae [M(L)2] for M = Mn(II), Co(II), Ni(II), Zn(II) and Cd(II); [M(L)X].nH2O for M = Cu(II) (X = AcO, n = 3), Pd(II) (X = Cl, n = 0) and UO2(II) (X = NO3, n = 0), and [Fe(L)Cl2(H2O)].2H2O. The molar conductance data reveal that the chelates are non-electrolytes. IR spectra show that the ligand is coordinated to the metal ions in a terdentate manner with ONN donor sites of the naphthyl OH, azo N and thiazole N. An octahedral structure is proposed for Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II) and UO2(II) complexes and a square planar structure for Cu(II) and Pd(II) complexes. The thermal behaviour of these chelates shows that water molecules (coordinated and hydrated) and anions are removed in two successive steps followed immediately by decomposition of the ligand molecule in the subsequent steps. The relative thermal stability of the chelates is evaluated. The final decomposition products are found to be the corresponding metal oxides. The thermodynamic activation parameters, such as E*, delta H*, delta S* and delta G* are calculated from the TG curves.
Spectrochim Acta A Mol Biomol Spectrosc 2005 Mar
PMID:Potentiometric, spectroscopic and thermal studies on the metal chelates of 1-(2-thiazolylazo)-2-naphthalenol. 1568 99

The extraction behaviour of Pr(III) from aqueous nitric acid medium employing benzoylacetone has been studied in presence of two crown ethers, viz., 15-crown-5 and benzo-15-crown-5 in chloroform medium using UV-vis absorption spectroscopy. The binary equilibrium constant (logk(ex)) for the complex [Pr(benzoylacetonate)(NO3(-))2(H(2)O)] in organic phase was found to be 1.170. The overall equilibrium constants (logK) for the ternary species [Pr(benzoylacetonate)(crown ether)(NO3(-))(2)] were estimated to be 4.01 and 4.41 for 15-crown-5 and benzo-15-crown-5, respectively. The trend in the equilibrium constant values were very much in accordance with the nature of substitution of the donor moiety. The extraction of Pr(III) by the benzoylacetone-crown ether combination was maximum at pH 3.0 and extraction decreases with increase in pH. It has been found that the extent of extraction of Pr(III) in organic phase as the binary as well as ternary complex [Pr(benzoylacetonate)(NO3(-))(2)(H(2)O)] and [Pr(benzoylacetonate)(crown ether)(NO3(-))(2)] increases with increase in concentration of the ligand. Similar trend is observed in the extraction by only donors. Enthalpies and entropies of formation for the ternary extraction process have been estimated. In addition, the effect of NaNO(3) as foreign salt was also studied and it was observed that with increase in ionic strength, percentage extraction increases.
Spectrochim Acta A Mol Biomol Spectrosc 2005 Apr
PMID:Absorption spectroscopic study of synergistic extraction of praseodymium with benzoyl acetone in presence of crown ether. 1574 Nov

Carbonic anhydrases (CA, EC 4.2.1.1.) catalyze reversible hydration of CO2 to HCO3- + H+. Bicarbonate transport proteins, which catalyze the transmembrane movement of membrane-impermeant bicarbonate, function in cooperation with CA. Since CA and bicarbonate transporters share the substrate, bicarbonate, we examined whether novel competitive inhibitors of CA also have direct inhibitory effects on bicarbonate transporters. We expressed the human erythrocyte membrane Cl-/HCO3- exchanger, AE1, in transfected HEK293 cells as a model bicarbonate transporter. AE1 activity was assessed in both Cl-/NO3- exchange assays, which were independent of CA activity, and in Cl-/HCO3- exchange assays. Transport was measured by following changes of intracellular [Cl-] and pH, using the intracellular fluorescent reporter dyes 6-methoxy-N-(3-sulfopropyl)quinolinium and 2',7'-bis-(2-carboxyethyl)-5-(and-6)carboxyfluorescein, respectively. We examined the effect of 16 different carbonic anhydrase inhibitors on AE1 transport activity. Among these 12 were newly-reported compounds; two were clinically used non-steroidal anti-inflammatory drugs (celecoxib and valdecoxib) and two were anti-convulsant drugs (topiramate and zonisamide). Celecoxib and four of the novel compounds significantly inhibited AE1 Cl-/NO3- exchange activity with EC50 values in the range 0.22-2.8 microM. It was evident that bulkier compounds had greater AE1 inhibitory potency. Maximum inhibition using 40 microM of each compound was only 22-53% of AE1 transport activity, possibly because assays were performed in the presence of competing substrate. In Cl-/HCO3- exchange assays, which depend on functional CA to produce transport substrate, 40 microM celecoxib inhibited AE1 by 62+/-4%. We conclude that some carbonic anhydrase inhibitors, including clinically-used celecoxib, will inhibit bicarbonate transport at clinically-significant concentrations.
Mol Membr Biol
PMID:Carbonic anhydrase inhibitors that directly inhibit anion transport by the human Cl-/HCO3- exchanger, AE1. 1576 72

The use of di-2-pyridyl ketone, (py)2CO, in zinc(II) nitrate chemistry has yielded a dinuclear complex and a cationic tetranuclear cluster. The 1:1 Zn(NO3)2.4H2O/(py)2CO reaction system in EtOH gives [Zn2(NO3)2{(py)2C(OEt)O}2].0.5H2O (1.0.5H2O), whereas the same reaction system in MeCN yields [Zn4(NO3)3{(py)2C(OH)O}4(H2O)](NO3) (2). The monoanionic derivatives of the hemiacetal and the gem-diol forms of di-2-pyridyl ketone have been derived from the ZnII-mediated addition of solvent (EtOH, H2O involved in MeCN) on the carbonyl group of (py)2CO. Each (py)2C(OEt)O- ion functions as an eta1:eta2:eta1:mu2 ligand in 1.0.5H2O chelating the two ZnII atoms through the 2-pyridyl nitrogen atoms and the common bridging, deprotonated oxygen atom; one asymmetric chelating nitrate completes six coordination at each metal center. The tetranuclear cluster cation of 2 has a cubane topology with the ZnII ions and the deprotonated oxygen atoms from the four eta1:eta3:eta1:mu3 (py)2C(OH)O- ligands occupying alternate vertices. Three monodentate nitrates and one aqua ligand complete the sixth coordination site at the metal ions. The two complexes have been characterized by IR and far-IR spectroscopies. Characteristic bands are discussed in terms of the known structures and the coordination modes of the nitrato ligands. Upon excitation at 371 nm, complex 2 displays blue photoluminescence in the solid state at room temperature with two emission maxima at 430 and 455 nm.
Spectrochim Acta A Mol Biomol Spectrosc 2005 May
PMID:Dinuclear versus tetranuclear cluster formation in zinc(II) nitrate/di-2-pyridyl ketone chemistry: synthetic, structural and spectroscopic studies. 1582 Aug 96

Peroxynitrite is a potent oxidant and nitrating species proposed as a direct effector of myocardial damage in a wide range of cardiac diseases. Whether peroxynitrite also acts indirectly, by modulating cell signal transduction pathways in the myocardium, has not been investigated. Here, we examined the ability of peroxynitrite to activate extracellular signal-related kinase (ERK), a MAP kinase which has been linked with hypertrophic and anti-apoptotic responses in the heart, in cultured H9C2 cardiomyocytes. Peroxynitrite elicited a concentration- and time-dependent activation of ERK, secondary to the upstream activation of MEK 1 (ERK kinase). Activation of MEK-ERK by peroxynitrite was related to the upstream activation of Raf-1 kinase, as ERK and MEK phosphorylation were prevented by the Raf-1 inhibitor BAY43-9006. These effects of peroxynitrite were not associated with the activation of p21(Ras), known as a common signaling target of cellular oxidative stress. In contrast to ERK activation mediated by the epidermal growth factor (EGF), ERK activation by peroxynitrite was not prevented by AG1478 (EGF receptor inhibitor). Peroxynitrite acted through oxidative, but not nitrative chemistry, as ERK remained activated while nitration was prevented by the flavanol epicatechin. In addition to ERK, peroxynitrite also potently activated two additional members of the MAP kinase family of signaling proteins, JNK and p38. Thus, peroxynitrite activates ERK in cardiomyocytes through an unusual signaling cascade involving Raf-1 and MEK 1, independently from EGFR and P21(Ras), and also acts as a potent activator of JNK and p38. These results provide the novel concept that peroxynitrite may represent a previously unrecognized signaling molecule in various cardiac pathologies.
J Mol Cell Cardiol 2005 May
PMID:Peroxynitrite activates ERK via Raf-1 and MEK, independently from EGF receptor and p21Ras in H9C2 cardiomyocytes. 1585 May 70

The title complex [Fe(II)(tidf-H2)(H2O)2](ClO4)2*H(2)O (tidf-H2 = tetraiminediphenolate ligand) has been prepared from a transmetallation reaction between [Mg2(tidf)](NO3)2*4H2O and an iron(II) salt in methanolic solutions under inert atmosphere conditions. It was characterized by analytical, magnetic and spectroscopic methods (Mossbauer, FTIR, UV-vis), by cyclic voltammetry as well as spectroelectrochemistry.
Spectrochim Acta A Mol Biomol Spectrosc 2005 Jun
PMID:Spectroscopic, redox and magnetic properties of a tetraiminediphenolate iron(II) macrocyclic complex: a model compound for iron proteins. 1586 68

Reaction of divalent cobalt(II) and trivalent ruthenium(III) salts (NO3, SCN and SO4) with macrocyclic ligands L1, L2 and L3 having N2S2, N4 and N5 core, have been designed and carry out. All these three macrocyclic ligands and their complexes were obtained in pure form. Their structures were investigated by using microanalytical analyses, IR, mass, magnetic moments, electronic and EPR spectral studies. The redox properties of the complexes were also examined by cyclic voltammetry. An interesting feature of complexes is that the relatively large rings of macrocyclic ligands prevent the macrocyclic rings from approaching the metal center as closely as they would, if they were not constrained. So the Ru-N distances are longer than expected due to ring size. Electrochemical studies show that the macrocyclic ligand L1 is more effective electron donors to ruthenium than of L2 and L3. Electronic spectral properties also show that the sulphur donor atom of L1 weakens the ligand field with respect to ligand-to-metal charge-transfer band. However it is expected that second-row transition metal-ligand bonds tend to be weaker than third-row transition metal-ligand bonds. There are well-established examples of reactions in which decreased of reactivity down a triad of transition metals is not observed. These novelties are usually attributed to pi-bonding effects for ligands such as carbon monoxide, solvent effects, or a change in mechanism.
Spectrochim Acta A Mol Biomol Spectrosc 2005 Dec
PMID:Spectral studies, cyclic voltammetry and synthesis of cobalt(II) and ruthenium(III) complexes with symmetric and asymmetric ring containing membered N2S2, N4, and N5 donor macrocyclic ligands. 1589 89

The complexes of Cr(III), Mn(II), Fe(III) and Cu(II) were synthesized with the macrocyclic ligand i.e. 2,3,9,10-tetraketo-1,4,8,11-tetraazacyclotetradecane. The ligand was prepared by the [2 + 2] condensation reaction of diethyloxalate and 1,3-diamino propane. These complexes were found to have the general composition M(L)X3 and M'(L)X2 [where M = Mn(II) and Cu(II), M' = Cr(III) and Fe(III), L = ligand (N4) and X = Cl-, NO3-, 1/2SO4(2-) and [CH3COO-]. The ligand and its transition metal complexes were characterized by the elemental analyses, molar conductance, magnetic susceptibility, mass, IR, electronic, and EPR spectral studies. On the basis of IR, electronic and EPR spectral studies an octahedral geometry has been assigned for Cr(III), Mn(II) and Fe(III) and a tetragonal geometry for Cu(II) complexes.
Spectrochim Acta A Mol Biomol Spectrosc 2005 Jul
PMID:Spectroscopic approach in characterization of chromium(III), manganese(II), iron(III) and copper(II) complexes with a nitrogen donor tetradentate, 14-membered azamacrocyclic ligand. 1591 3

A novel 6-hydroxy chromone-3-carbaldehyde benzoyl hydrazone ligand and its four complexes, [LnL2(NO3)2]NO3 [Ln = Eu(1), Sm(2), Tb(3), Dy(4)], were synthesized. The complexes were characterized by the elemental analyses, molar conductivity and IR spectra. The crystal and molecular structure of Sm(III) complex was determined by single-crystal X-ray diffraction: crystallized in the triclinic system, space group P-1, Z = 1, a = 11.037(4) A, b = 14.770(5) A, c = 15.032(7) A, alpha = 60.583(4), beta = 75.528(7), gamma = 88.999(4), R1 = 0.0349. The fluorescence properties of complexes in the solid state and in the organic solvent were studied in detail, respectively. Under the excitation of ultraviolet light, strong red fluorescence of solid europium complex was observed. But the green fluorescence of solid terbium complex was not observed. These observations show that the ligand favor energy transfers to the emitting energy level of Eu3+. Some factors that influence the fluorescent intensity were also discussed.
Spectrochim Acta A Mol Biomol Spectrosc 2006 Jan
PMID:Synthesis, structure, infrared and fluorescence spectra of new rare earth complexes with 6-hydroxy chromone-3-carbaldehyde benzoyl hydrazone. 1595 Dec 32


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