Copper ionic strength dependence

Another illustration of the power of molecular dynamics simulation can be drawn from the sphere of enzyme catalysis. Many enzyme-catalyzed reactions proceed at a rate that depends on the diffusion-limited association of the substrate with the active site. Sharp et al. [28] have carried out Brownian dynamics simulations of the association of superoxide anions with superoxide dismutase (SOD). The active center in SOD is a positively charged copper atom. The distribution of charge over the enzyme is not uniform, and so an electric field is produced. Using their model, Sharp et al. [28] have shown that the electric field enhances the association of the substrate with the enzyme by a factor of 30 or more. Their calculations also predict correctly the response of the association rate to changes in ionic strength and amino... 

The oxidized and reduced forms of blue copper proteins can coexist in equilibrium in solution. This allows two identical molecules to exchange one electron, giving the so-called electron self-exchange (ESE) reaction (Marcus and Sutin, 1985). The rates of this process usually depend on the pH, temperature, and ionic strength of the solution. When the two forms... 

Copper also was removed by adsorbing colloid flotation using ferric hydroxide floe and SDS surfactant. Optirenm removal occurred in the pH range 6-8, depending on ionic strength. The 99.98% removal was achieved at pH 7.5 with an initial copper concentration of SO mg/L. ... 

These claims are not realistic [51-53] indeed, although certain cation impurities are removed from sodium azide, it contains foreign anions that are carried through. Also, the exchange resins themselves contain cation impurities, notably iron and copper, which are complexed and eluted as anionic azido complexes, thus introducing new impurities. One of them is the built-in red indicator, namely, azidoiron anions. Their chemical composition and retention on the resin, however, depend on the ionic strength (concentration) of the eluent, and elution at the point of proton exhaustion would be coincidental. 

Realization of the aqneons phase metal speciation is important to match a ligand to a specific metal ion. Heavy metal ions, for instance, can exist in various complex forms depending on the conditions of the solutions to be treated such as pH, counter ion concentrations, and ionic strength. For example, copper (I) exists in three different complex forms in cyanide solutions, such as Cu(CN)2 , Cu(CN)3, and... 

Cu(III)(peptide)], with [Cu(I)(dmp)2], where dmp is 2,9-dimethyl-1,10-phen-anthroline, are rapid, outer-sphere processes which show some adherence to Marcus behavior,although the [Cu(dmp)2] self-exchange rate appears to be very dependent on the cross reaction,a lower limit of 3 X 10" mol" liter s arising from the [Cu(III)(peptide)] reactions, while a value of 9 x 10 mol liter s" is obtained from reaction with [IrCle], both at 25°C and 0.10 M ionic strength.Reactions of the copper(I) complex of the sterically hindered phenyl sulfonate derivative of dmp, [Cu(dpmp)2], with [Cu(III) (peptide)] are complicated by limiting rate behavior which is ascribed to activation of the copper(III) complex [reaction (25)]... 

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