Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Proton-ligand dissociation and metal-ligand formation constants of 2-amino-4-chloro-6-[alpha-(phenyl)ethylidenehydrazino]pyrimidine; (AHP) and its p-chloro (ClAHP) and p-methoxy (OMeAHP) derivatives (Str.I&II) with Mn2+, Co2+ Ni2+, Cu2+, Zn2+, Cd2+, UO2(2+), Th4+, Ce3+ and Pr3+ ions have been evaluated potentiometrically in 75% (v/v) dioxane-water and 0.1 mol dm(-3) KNO3. The thermodynamic functions (deltaG, deltaH and deltaS) for the complexation of OMeAHP were evaluated and discussed. The effect of the temperature, dielectric constant of the solvents, mole fraction of dioxane and ionic strength of the medium on the stability of Pr3+-complexes show that the stability of the chelates increases by increasing both the electron repelling property of the substituents and the organic solvent content, and by decreasing the temperature, the ionic strength and the dielectric constant of the medium.
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PMID:Stability constants and thermodynamic parameters of Mn2+, Co2+, Ni2+ Cu2+, Zn2+, Cd2+, UO2(2+), Th4+, Ce3+ and Pr3+-complexes with some Schiff base hydrazones containing the pyrimidine moiety. 1273 93

Nevus comedonicus is uncommon abnormality of pilosebaceous unit, clinically characterized as confluent clusters of dilated follicular orifices plugged with pigmented keratinous material that resembles open comedones. It is suggested that nevus comedonicus is an uncommon variant of adnexal hamartoma, which clinically appears as linear group of open comedones. Since Kofmann's description of nevus comedonicus in 1895, there have been reports of this rare cutaneous disorder associated with developmental anomalies. We present a case of a 19-year-old woman with numerous 1-3 mm size darkly pigmented, keratic plugs clustered in linear unilateral patches on left abdominal part. Our treatment consisted of the avoidance of the formulations containing nickel sulfate and carba mixture, daily local application of tretinoin 0.1% gel and corticosteroid ointment (momethasone furoate). After 4 weeks of local therapy cosmetic result was evident. The slight resolution of keratin plugs could also be seen. Two months after the treatment, there were no visible skin exacerbations.
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PMID:Nevus comedonicus--case report and review of therapeutical approach. 1467 Feb 22

Gram-positive pathogens synthesize isopentenyl diphosphate, the five-carbon precursor of isoprenoids, via the mevalonate pathway. The enzymes of this pathway are essential for the survival of these organisms, and thus may represent possible targets for drug design. To extend our investigation of the mevalonate pathway in Enterococcus faecalis, we PCR-amplified and cloned into pET-28b the mvaK1 gene thought to encode mevalonate kinase, the fourth enzyme of the pathway. Following transformation of the construct EFK1-pET28b into Escherichia coli BL21(DE3) cells, the expressed C-terminally hexahistidine-tagged protein was purified on a nickel affinity support to apparent homogeneity. The purified protein catalyzed the divalent ion-dependent phosphorylation of mevalonate to mevalonate 5-phosphate. The specific activity of the purified kinase was 24 micromole/min/mg protein. Based on sedimentation velocity data, E. faecalis mevalonate kinase exists in solution primarily as a monomer with a mass of 32.2 kD. Optimal activity occurred at pH 10 and at 37 degrees C. Delta H(a) was 22 kcal/mole. Kinetic analysis suggested that the reaction proceeds via a sequential mechanism. K(m) values were 0.33 mM (mevalonate), 1.1 mM (ATP), and 3.3 mM (Mg(2+)). Unlike mammalian mevalonate kinases, E. faecalis mevalonate kinase utilized all tested nucleoside triphosphates as phosphoryl donors. ADP, but not AMP, inhibited the reaction with a K(i) of 2.7 mM.
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PMID:Enterococcus faecalis mevalonate kinase. 1476 74

The well-mixed copper-nickel nanoparticles were prepared when the molar ratio of Cu2+ to Ni2+ was 1:1 by simultaneous reduction of CuSO4 and NiCl2 with hydrazine in the microemulsion of SDS/n-butanol/n-heptane/water at 70 degrees C, and was characterized by TEM, ED, TGA, EDS, and XRD. ED analysis and XRD patterns suggest the formation of the homogeneous alloy structure in the bimetallic nanoparticles. Average size of the sample calculated from the full width at medium height of peak 111 in the XRD patterns using Scherrer formula is 5.53 nm. TEM photographs show a narrow distribution of Cu-Ni nanoparticles that essentially are monodispersed and the mean diameter is 12 nm. The results indicate that the composition and size of alloy nanoparticles depend on the mole ratio of H2O to SDS, the method of addition of Cu2+ and Ni2+, and the mole ratio of Cu2+ and Ni2+ in the initial precursor solution.
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PMID:Preparation of Cu-Ni alloy nanocrystallites in water-in-oil microemulsions. 1606 Dec 44

Nickel sulfide and copper sulfide nanocrystals were synthesized by adding elemental sulfur to either dichlorobenzene-solvated (copper sulfide) or oleylamine-solvated metal(II) precursors (nickel sulfide) at relatively high temperature to produce the metal sulfide. Nickel sulfide nanocrystals are cubic Ni(3)S(4) (polydymite) with irregular prismatic shapes, forming by a two-step reduction-sulfidation mechanism where Ni(II) reduces to Ni metal before sulfidation to Ni(3)S(4). Despite extensive efforts to optimize the Ni(3)S(4) nanocrystal size and shape distributions, polydisperse nanocrystals are produced. In contrast, copper sulfide nanocrystals can be obtained with narrow size and shape distributions. The copper sulfide stoichiometry depended on the Cu:S mole ratio used in the reaction: Cu:S mole ratios of 1:2 and 2:1 gave CuS (covellite) and Cu(1.8)S (digenite), respectively. CuS nanocrystals formed as hexagonal disks that assemble into stacked ribbons when cast from solution onto a substrate. CuS, Cu(1.8)S, and Ni(3)S(4) differ from the Cu(2)S and NiS nanocrystals obtained by solventless decomposition of metal thiolate single source precursors, in terms of stoichiometry for copper sulfide, and both stoichiometry and morphology for nickel sulfide [Ghezelbash, A.; Sigman, M. B., Jr.; Korgel, B. A. Nano Lett. 2004, 4, 537-542. Sigman, M. B. Ghezelbash, A.; Hanrath, T.; Saunders, A. E.; Lee, F.; Korgel, B. A. J. Am. Chem. Soc. 2003, 125, 16050-16057].
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PMID:Nickel sulfide and copper sulfide nanocrystal synthesis and polymorphism. 1620 21

Raman spectra of aprotic N,N-dimethylformamide (DMF) and protic N-methylformamide (NMF) mixtures containing manganese(II), nickel(II), and zinc(II) perchlorate were obtained, and the individual solvation numbers around the metal ions were determined over the whole range of solvent compositions. Variation profiles of the individual solvation numbers with solvent composition showed no significant difference among the metal systems examined. In all of these metal systems, no preferential solvation occurs in mixtures with DMF mole fraction of x(DMF) < 0.5, whereas DMF preferentially solvates the metal ions at x(DMF) > 0.5. The liquid structure of the mixtures was also studied by means of small-angle neutron scattering (SANS) and low-frequency Raman spectroscopy. SANS experiments demonstrate that DMF molecules do not appreciably self-aggregate in the mixtures over the whole range of solvent composition. Low-frequency Raman spectroscopy suggests that DMF molecules are extensively hydrogen-bonded with NMF in NMF-rich mixtures, whereas NMF molecules extensively self-aggregate in DMF-rich mixtures, although the liquid structure in neat NMF is partly ruptured. The bulk solvent structure in the mixtures thus varies with solvent composition, which plays a decisive role in developing the varying profiles of the individual solvation numbers of metal ions in the solvent mixtures.
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PMID:Liquid structure and preferential solvation of metal ions in solvent mixtures of N,N-dimethylformamide and N-methylformamide. 1645 Oct 10

The absorbance changes that occur when the mole ratio of the components of ligand complex equilibria is varied while the concentration of one component is kept constant (mole ratio method) allow evaluating stability constants in favourable conditions. Values of the corresponding stability (association) constants are normally assigned on the basis of spectrophotometric analysis. Determination of stability constants can be performed by a number of linear procedures, but most of these, suffer from theoretical and practical drawbacks, e.g., linear transformation of the rectangular hyperbola type of binding constants, is valid only when one of the two species is present in a large excess. A rigorous treatment of the experimental mole ratio data for 1:1 weak complexes is carried out in this paper with the aim of eliminating some of the assumptions involved in the other methods usually applied for evaluating stability constants. Orthogonal regression is required in order to take into account the error in both axes. The method has been applied to literature data for the iron(III)-thiocyanate and nickel(II)-selenocyanate systems, as well as to a number of host-guest cyclodextrin complexes.
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PMID:A bilogarithmic method for the spectrophotometric evaluation of stability constants of 1:1 weak complexes from mole ratio data. 1664 26

TrzN, the broad-specificity triazine hydrolase from Arthrobacter and Nocardioides spp., is reportedly in the amidohydrolase superfamily of metalloenzymes, but previous studies suggested that a metal was not required for activity. To help resolve that conundrum, a double chaperone expression system was used to produce multimilligram quantities of functionally folded, recombinant TrzN. The TrzN obtained from Escherichia coli (trzN) cells cultured with increasing zinc in the growth medium showed corresponding increases in specific activity, and enzyme obtained from cells grown with 500 muM zinc showed maximum activity. Recombinant TrzN contained 1 mole of Zn per mole of TrzN subunit. Maximally active TrzN was not affected by supplementation with most metals nor by EDTA, consistent with previous observations (E. Topp, W. M. Mulbry, H. Zhu, S. M. Nour, and D. Cuppels, Appl. Environ. Microbiol. 66:3134-3141, 2000) which had led to the conclusion that TrzN is not a metalloenzyme. Fully active native TrzN showed a loss of greater than 90% of enzyme activity and bound zinc when treated with the metal chelator 8-hydroxyquinoline-5-sulfonic acid. While exogenously added zinc or cobalt restored activity to metal-depleted TrzN, cobalt supported lower activity than did zinc. Iron, manganese, nickel, and copper did not support TrzN activity. Both Zn- and Co-TrzN showed different relative activities with different s-triazine substrates. Co-TrzN showed a visible absorption spectrum characteristic of other members of the amidohydrolase superfamily replaced with cobalt.
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PMID:TrzN from Arthrobacter aurescens TC1 Is a zinc amidohydrolase. 1688 54

Iron is essential for the survival of almost all organisms, although excess iron can result in the generation of free radicals which are toxic to cells. To avoid the toxic effects of free radicals, the concentration of intracellular iron is generally regulated by the ferric uptake regulator Fur in bacteria. The 150 aa fur ORF from Listeria monocytogenes was cloned into pRSETa, and the His-tagged fusion protein was purified by nickel affinity column chromatography. DNA binding activity of this protein was studied by an electrophoretic mobility shift assay using the end-labelled promoters P(fhuDC) and P(fur). The results showed a decrease in migration for both promoter DNAs in the presence of the Fur protein, and the change in migration was competitively inhibited with an excess of the same unlabelled promoters. No shift in migration was observed when a similar assay was performed using non-specific end-labelled DNA. The assay showed that binding of Fur to P(fur) or P(fhuDC) was independent of iron or manganese ions, and was not inhibited in the presence of 2 mM EDTA. Inductively coupled plasma MS of the Fur protein showed no iron or manganese, but 0.48 mole zinc per mole protein was detected. A DNase I protection assay revealed that Fur specifically bound to and protected a 19 bp consensus Fur box sequence located in the promoters of fur and fhuDC. There was no requirement for iron or manganese in this assay also. However, Northern blot analysis showed an increase in fur transcription under iron-restricted compared to high-level conditions. Thus, the study suggests that under in vitro conditions, the affinity of the Fur protein for the 19 bp Fur box sequence does not require iron, but iron availability regulates fur transcription in vivo. Thus, the regulation by Fur in this intracellular pathogen may be dependent on either the structure of the DNA binding domain or other intracellular factors yet to be identified.
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PMID:Molecular characterization of the Fur protein of Listeria monocytogenes. 1737 19

Utilizing similar methods and ideas of QSAR in metal toxicity assessment, we tried to establish the relationship between the ion characteristics of heavy metals and the biosorption capacity by waste biomass of Saccharomyces cerevisiae, obtained from a local brewery. The biosorption experiment was carried out and the maximum biosorption capacity (q(max)) was determined by the Langmuir isotherm model. The values of q(max) decreased in order on mole basis: Pb2+ > Ag+ > Cr3+ > Cu2+ > Zn2+ > Cd2+ > Co2+ > Sr2+ > Ni2+ > Cs+. The biomass prefer to bind class B ions (Pb2+ and Ag+), then borderline ions, and last hard ions (Sr2+ and Cs+) based on the HASB principle. Twenty two parameters of physiochemical characteristics of ions were selected to correlate q(max). Linear regression analysis showed that only one parameter, i.e., the covalent index X2(m)r was correlated well to q(max) for all metal ions tested. The greater the covalent index value of metal ion was, the greater was potential to form covalent bonds with biological ligands, and the larger was the metal ion biosorption. Classification of metal ions (for divalent ion or for soft-hard ion) improved the models. More properties such as polarizing power Z2/r or the first hydrolysis constant /lgK(OH)/ or ionization potential IP were statistically significant. X2(m)r seemed to be suitable to account for metal ions containing soft ions, whereas Z2/r, /lgK(OH)/ and IP suitable for only soft ions or metal ions without soft ions.
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PMID:[Relationship of biosorption capacity of heavy metal ions by Saccharomyces cerevisiae and their ionic characteristics]. 1792 2


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