Interactions of histidine and other imidazole derivatives with transition metal ions in chemical and biological systems

Sundberg, Richard J.; Martin, R. Bruce

doi:10.1021/cr60290a003

Cited by 1,146 publications

(691 citation statements)

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“…The acidity constants of the carboxylic acids were calculated according to equilibrium (I), and the stability constants of the corresponding Cu2 ' and Zn2+ complexes according to equilibrium (2). A significant excess concentration of metal ions (M2') over that of the carboxylate ligands (CA-) was used in the experiments, hence all observations may be fully characterized by equilibria ( I ) and (2).…”

Section: Resultsmentioning

confidence: 99%

“…Thus a statistical factor [28,29] appears to favor ligand binding to the free Zn2 t . However, ligand binding to Zn2+ displays a 'cooperativity', probably due to a reduction in coordination number of the free ion on ligand binding, so that the stability constants for binding of successive ligands are often comparable [2]. Thus for Zn" the statistical factor is reduccd to only a few tenths of a log unit.…”

Section: Metalloproteins: Carhoxypeptidase Und Carbonic Unh-vdrusementioning

confidence: 99%

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An estimation of the equivalent solution dielectric constant in the active-site cavity of metalloenzymes. Dependence of carboxylate - metal-ion complex stabilities on the polarity of mixed aqueous/organic solvents

et al. 1985

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The stability constants of the 1:l complexes between Cu2+ and Zn2+ with formate, acetate and several phenylalkanecarboxylates, i.e. C6H5-(CH2)n-C00-with n = 0 to 5, are summarized for water, 50% aqueous ethanol and 50% aqueous dioxane ( I = 0.1 M; 25°C): Complex stability depends upon carboxylate group basicity. The influence of varying amounts of ethanol or dioxane (up to 90%) on the stability of the Cu2' and Zn2+ (M") complexes with formate and acetate (CA) was measured by potentiometric pH titrations. The values for pf(,(,., and log K&-.) increase, as expected, with increasing amounts of the organic solvents, i.e. with decreasing solvent polarity. The changes in the equilibrium constants are also evaluated with regard to the mole fractions of the organic solvents and the corresponding dielectric constants. These results may be used to estimate for low dielectric cavities in proteins the equivalent solution dielectric constant on the basis of enhanced carboxylate basicity or metal ion binding capability (method 1). Furthermore, the measured stability constants are used for comparisons of the coordination tendency of carboxylate ligands towards zinc(I1)-metalloenzymes (method 2) ; in this way the equivalent solution dielectric constants in the active-site cavities of bovine carbonic anhydrase and carboxypeptidase A are estimated: the values are of the order of 35 and 70, respectively. This method seems to be generally applicable to metalloproteins.Among the prominent binding sites for metal ions in biological systems are the carboxylate, imidazole and amino groups [l -31. They are not only part of the low-molecularmass ligands [4], but occur also as side chains in proteins, sometimes located in low dielectric cavities.The acidity constants of N and 0 ligands are clearly dependent upon the polarity of the solvent [l, 51: the basicity of N ligands (with no charge) usually decreases as the polarity of the solvent decreases, while the basicity of 0 ligands (with a negative charge) increases markedly as the dielectric constant decreases. The change in the stability of complexes [l] is in accord with the change in basicity, but with N ligands the stability decreases usually only slightly, as the polarity of the solvent decreases, while with 0 ligands the increase in stability may be quite pronounced. This means that the affinity towards metal ions of an imidazole moiety is expected to change little with a change in solvent polarity, while the change Correspondence to H . Sigel, Institut fur Anorganische Chemie der Universitat Basel, Spitalstrasse 51, CH-4056 Basel, SwitzerlandAhhreviutions. Ac-, acetate; CA-, carboxylate ligand; M 2 + , general divalent metal ion. Additionally, in the Supplement: Bz-, benzoate; PAC-, 2-phenylacetate; PBu-, 4-phenylbutyrate; PCa-, 6-phenylcapronate; PPr -, 3-phenylpropionate; PVa-, 5-phenylvalerate.Miniprint supplement. Some parts of this work, including Materials and Measurements, and further details on Results and Discussion, are given in a miniprint supplement a t the end of the p...

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Section: Resultsmentioning

confidence: 99%

Section: Metalloproteins: Carhoxypeptidase Und Carbonic Unh-vdrusementioning

confidence: 99%

An estimation of the equivalent solution dielectric constant in the active-site cavity of metalloenzymes. Dependence of carboxylate - metal-ion complex stabilities on the polarity of mixed aqueous/organic solvents

et al. 1985

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“…These conserved histidines are found within the three conserved domains of histidine clusters [1]. It has been demonstrated that such conserved histidine residues are involved in the catalytic actions of many enzymes, for example dehydrogenases [13], and can bind metal irons [14]. Histidine, with its weakly basic imidazole group (pK~ = 6.0), is the amino acid that can donate a proton to serve as a ligand to transition metals in the neutral pH range.…”

Section: Introductionmentioning

confidence: 99%

Site‐directed mutagenesis of histidine residues in the Δ12 acyl‐lipid desaturase of Synechocystis

et al. 1995

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In the cyanobacterium Synechocystis sp. PCC 6803, there are four acyl-lipid desaturases that are, respectively, specific to the A6, A9, A12 and to3 positions of fatty acids. The desA gene for the A12 acyl-lipid desaturase was modified by sitedirected mutagenesis, such that four of the histidine residues that are conserved in the four desaturases and one histidine residue that is not conserved were replaced by arginine, and the mutated desA genes were overexpressed in Escherichia coil All of these mutations eliminated the A12 desaturase activity. These results demonstrate that the five histidine residues are essential for the activity of the A12 desaturase, perhaps by providing the ligands for the catalytic Fe center.

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“…They are important ligands for complexation with transition metals 3 and have also been applied in laser dyes 4 , chemosensing 5 , fluorescence and nonlinear organic materials 6 . Thiazoles are important nitrogen and sulfur-containing five membered heterocyclic compounds.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Photophysical Properties of 5-Methoxy-naphtho[1,2-d]thiazole-2-carboxylic Acid

2017

Chem Sci Trans

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Synthesis of 5-methoxynaphtho[1, 2-d]thiazole-2-carboxylic acid was developed from new synthetic route starting from using potassium ferricyanide as catalyst. The absorption and fluorescence properties of structurally related 4-methoxynaphthalene-1-ylamine (4), N-(4-methoxynaphthalene-1-yl)-oxalamic acid ethyl ester (5), 2-(4-methoxynaphthalene-1-ylamino)-2-thioxoacetic acid (6) and 5-methoxynaphtho[1,2-d]thiazole-2-carboxylic acid (7) were investigated in 4 different solvents. The absorption maxima of these compounds (except 7) in the order C 6 H 6 > cyclohexane >MeOH>EtOH+HCl. The spectral characteristics are solvent and compound specific. Fluorophores with electron withdrawing group have larger fluorescence quantum yields and greater solvatochromism than the compounds with electron donating groups. Protic solvents yielded higher fluorescence quantum efficiency. While no such relationship exists between the latter and electronic absorption maxima, fluorescence emission maxima, fluorescence quantum efficiency and Stokes shift.

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Interactions of histidine and other imidazole derivatives with transition metal ions in chemical and biological systems

Cited by 1,146 publications

References 115 publications

An estimation of the equivalent solution dielectric constant in the active-site cavity of metalloenzymes. Dependence of carboxylate - metal-ion complex stabilities on the polarity of mixed aqueous/organic solvents

An estimation of the equivalent solution dielectric constant in the active-site cavity of metalloenzymes. Dependence of carboxylate - metal-ion complex stabilities on the polarity of mixed aqueous/organic solvents

Site‐directed mutagenesis of histidine residues in the Δ12 acyl‐lipid desaturase of Synechocystis

Synthesis and Photophysical Properties of 5-Methoxy-naphtho[1,2-d]thiazole-2-carboxylic Acid

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