Cadmium-113 Nuclear Magnetic Resonance Research Articles

Cadmium-113 NMR and Theoretical Studies of Complexation of Cadmium Ion with 15-Crown-5 and Benzo-15-Crown-5 in Acetonitrile and Its Binary Mixtures with Water and Nitromethane

Cadmium-113 nuclear magnetic resonance was used as a sensitive probe to study the interaction of Cd2+ ion with 15-crown-5 and benzo-15-crown-5 in acetonitrile and its binary mixtures with water and nitromethane. The observed 113Cd-NMR chemical shift changes at a constant Cd2+ ion concentration and varying crown concentrations were found to be consistent with a fast exchange model. The formation constants of the resulting 1:1 complexes were evaluated from computer fitting of the chemical shift-mole ration data to an equation which relates the observed chemical shifts to the formation constant. The geometries of the macrocyclic ligands and their cadmium complexes were optimized by an ab initio method, and the calculated binding energies of the resulting complexes were compared. Both the 113Cd-NMR and ab initio studies revealed that, in all cases, 15-crown-5 forms a more stable Cd2+ complex than benzo-15-crown-5. In the case of the both crown ethers, there is an inverse relationship between the stability of complexes and solvating ability of the solvent systems used.

Cadmium-113 nuclear magnetic resonance studies of cadmium(II)—carboxylate complexes in aqueous solution

A variety of complexes of cadmium with mono- and di-carboxylic acids in aqueous solution were investigated using 113Cd NMR spectroscopy. A single averaged chemical shift was obtained even at reduced temperature, showing that the cadmium–monocarboxylate complexes are undergoing rapid exchange in solution. Using the known stability constants, the individual chemical shifts were calculated to be in the ranges δ–22 to –24 and –39 to –40 for [CdL]+ and [CdL2](L = carboxylate) species respectively: carboxylates with higher basicity tend to increase the shielding of the cadmium in the complexes. In case of dicarboxylic acids HO2C(CH2)nCO2H (n= 0–3) the 113Cd nucleus showed greater shielding with increasing n. The upfield chemical shift observed for the dialkyl-substituted malonate complexes of CdII compared to the malonate complex is caused by the steric effect hindering ring formation.

Layered, network and chain structures of cadmium(II) malonate: crystal structure and cadmium-113 nuclear magnetic resonance studies

Three structurally non-identical cadmium(II) malonate compounds have been obtained: polymeric tetraaquabis(malonato)dicadmium(II)1, polymeric monoaqua(malonato)cadmium(II) monohydrate 2 and polymeric triaqua(malonato)cadmium(II) monohydrate 3. The layered-structure compound 1 is the initial product formed at room temperature, and has two cadmium sites in distinct chemical and magnetic environments: six- and eight-co-ordinate cadmium involving oxygen donors including two water molecules, characterized by two 113Cd NMR resonances at δ 18 and –107, respectively. Compound 2, which has a three-dimensional network structure, is formed irreversibly when 1 is heated at 60 °C or exposed to sunlight: its seven-co-ordinate cadmium site involves one six-membered and two four-membered chelate rings and one water molecule (δ–47). Compound 3 has an unusual chain structure and is formed reversibly when 2 is heated at 100 °C: a different seven-co-ordinated cadmium site involves two four-membered rings and three water molecules (δ–53). The results of the cross polarization magic angle spinning 113Cd NMR study of the six-, seven- and eight-co-ordination sites show that cadmium atoms with higher co-ordination numbers tend to be more shielded.

Repair of DNA Methylphosphotriesters Through a Metalloactivated Cysteine Nucleophile

The Escherichia coli Ada protein repairs methylphosphotriesters in DNA by direct, irreversible methyl transfer to one of its own cysteines. Upon methyl transfer, Ada acquires the ability to bind specific DNA sequences and thereby to induce genes that confer resistance to methylating agents. The amino-terminal domain of Ada, which comprises the methylphosphotriester repair and sequence-specific DNA binding elements, contains a tightly bound zinc ion. Analysis of the zinc binding site by cadmium-113 nuclear magnetic resonance and site-directed mutagenesis revealed that zinc participates in the autocatalytic activation of the active site cysteine and may also function as a conformational switch.

2] Cadmium-113 nuclear magnetic resonance applied to metalloproteins

Publisher Summary Among the naturally occurring isotopes of cadmium there are two, 113 Cd and 111 Cd, that have a nuclear spin of ½ and are useful as nuclear magnetic resonance (NMR) probes for cadmium-containing molecules. Both isotopes are present at a significant percent natural abundance, namely, 12.75 and 12.26% for 111 Cd and 113 Cd, respectively. They are both obtainable in 96% purity. Although there is only one naturally occurring well-characterized protein, metallothionein, that accumulates cadmium, most metalloproteins containing the Zn 2+ ion—5 d 10 electron configuration—can be substituted with the heavier Cd 2+ ion (6 d 10 ). In the case of metalloenzymes, the Cd substitution has often led to a protein that maintains measurable catalytic activity. For a variety of Zn-containing DNA-binding proteins that require Zn to maintain the fold required for DNA recognition and binding, the Cd-substituted proteins have retained DNA binding. Thus, from both structural and functional standpoints 113 Cd ( 111 Cd) NMR can be used as a valuable probe of zinc metalloprotein structure and function. The cadmium(II) ion has an ionic radius of 0.97 A nearly the same as that of Ca 2+ , 0.99 A (Pauling radii). Thus, Cd 2+ can be substituted at most Ca 2+ binding sites found in proteins. The Cd 2+ ion can also fit the sites occupied by the Cu + ion (5 d 10 ) and thus can be used to probe the metal sites in copper electron transfer proteins in which copper alternates between the Cu + and Cu 2+ states. Metal ion replacement employs anaerobic techniques under which the Cu + ion is removed and replaced by 113 Cd 2+ . This chapter describes the application of 113 Cd NMR methods to the study of metalloproteins.

Investigation of the metal-algae binding site with cadmium-113 nuclear magnetic resonance

Download Hi-Res ImageDownload to MS-PowerPointCite This:Environ. Sci. Technol. 1990, 24, 9, 1309-1312

Carbon-13 and cadmium-113 nuclear magnetic resonance evidence for a novel transannular oscillation of cadmium(II) in the pendant arm macrocyclic complex [1,4,8,11-tetrakis(2-hydroxyethyl)-1,4,8,11-tetraazacyclotetradecane]cadmium(II)

A {sup 13}C NMR study of (1,4,8,11-tetrakis(2-hydroxyethyl)-1,4,8,11-tetraazacyclotetradecane)cadmium(II), (Cd(THEC)){sup 2+}, in CD{sub 3}OD shows that the most probable structure for (Cd(THEC)){sup 2+} incorporates the 1,4,8,11-tetraazacyclotetradecane ring in the trans III configuration. In this structure Cd(II) is above the tetraaza plane and is trigonal-prismatically coordinated by four ring nitrogens and two hydroxyethyl pendant arms attached to either end of the same 1,3-diaminopropane moiety. The {sup 13}C CPMAS NMR spectrum of solid (Cd(THEC)){sup 2+} is also consistent with this structure. Dynamic {sup 13}C NMR studies of natural abundance (Cd(THEC)){sup 2+} and of (Cd(THEC)){sup 2+} in which both carbons of each of the hydroxyethyl arms are 99 atom % enriched in {sup 13}C are consistent with a rapid oscillation of Cd(II) through the macrocyclic annulus of THEC. The {sup 13}C-enriched hydroxyethyl arms are characterized by {sup 13}C AB quartets under conditions of slow exchange but show a novel coalescence to a singlet under fast-exchange conditions consistent with the relative chemical shifts of the methylene carbons of the hydroxyethyl arm being reversed when it changes from the mono- to the bidentate coordination state. The pairwise exchange of the hydroxyethyl arm between the monodentate and bidentate environments is characterized by k(298.2 K) = 34,200 {plus minus} more » 1,800 s{sup {minus}1}, {Delta}H{double dagger} = 44.00 {plus minus} 0.56 kJ mol{sup {minus}1}, and {Delta}S{double dagger} = {minus}10.6 {plus minus} 2.2 J K{sup {minus}1} mol{sup {minus}1}. {sup 13}C and {sup 113}Cd NMR spectra show that intermolecular THEC and Cd(II) exchange on (Cd(THEC)){sup 2+} is a much slower process. 29 refs., 6 figs. « less

Solid-state cadmium-113 nuclear magnetic resonance study of exchanged montmorillonites

The solid-state {sup 113}Cd nuclear magnetic resonance of cadmium adsorbed on montmorillonite was investigated. An analysis of three montmorillonite samples and a brief comparison with other clays are included. The spectra contain cadmium oxoanion components of differing line widths with differential sensitivities to preparation conditions. Echo train experiments at various temperature and {tau} delays indicate that the line widths are governed by dynamic processes rather than chemical shift dispersion. These same experiments show the heterogeneity of the cadmium sites. Included in the study are the effects of pH variation, exchanged clay form, pretreatment with alginic and humic acids, and air- and freeze-drying. These results are described in terms of ions in different environments and ion motion. For montmorillonite some of these sites are considered to be near iron in the octahedral layer. The interlayer ion diffusion is related to metal ion transport in clay layers and the potential consequences of migration.

Cadmium-113 nuclear magnetic resonance spectroscopy of Cd2+-substituted heme and myoglobin

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCadmium-113 nuclear magnetic resonance spectroscopy of Cd2+-substituted heme and myoglobinMichael A. Kennedy and Paul D. EllisCite this: J. Am. Chem. Soc. 1989, 111, 9, 3195–3203Publication Date (Print):April 1, 1989Publication History Published online1 May 2002Published inissue 1 April 1989https://doi.org/10.1021/ja00191a014RIGHTS & PERMISSIONSArticle Views171Altmetric-Citations19LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (948 KB) Get e-Alerts Get e-Alerts

Sulphonamide nitrogen-containing, nitrogen-protected amino acids interacting with the Cd2+ion. A cadmium-113 nuclear magnetic resonance and potentiometric study. X-Ray diffraction of [Cd(ts-β-alaO)2(H2O4)

α-Alanine and β-alanine, N-protected by a tosyl (toluene-p-sulphonyl) group, bind Cd2+ acting initially as a simple carboxylate at low pH, and, at increasing pH, as N,O-bidentate ligands, through the carboxylic oxygen and the deprotonated amide nitrogen atoms. In the latter case they give rise to five- and six-membered ring chelate species, respectively. Cadmium-113 n.m.r. and potentiometric measurements reveal that the stability of the complexes is almost unaffected by the chelate ring size. The five-membered ring chelate species has a more deshielded chemical shift and only a slightly greater stability than the six-membered species. The crystal and molecular structures of the [Cd(ts-β-alaO)2(H2O)4](ts-β-alao =N-tosyl-β-alaninate monoanion) complex have been solved. Crystal data are: monoclinic, space group P21/c, a= 14.956 (6), b= 5.472(2), c= 16.860(7)Å, β= 107.36(3)°, Z= 2, and R= 0.039 for 1 635 reflections. The amina acid molecule binds through the unidentate carboxylate group and the structure consists of discrete units in which the Cd2+ exhibits a nearly regular octahedral geometry.

Cadmium-113 nuclear magnetic resonance spectroscopic study of mixed-ligand tetranuclear clusters of the type [Cd4(EPh)x(E'R)10-x]2- and of the mixed-metal clusters [CdxZn4-x(SPh)10]2-

Cadmium-113 nuclear magnetic resonance spectroscopic study of mixed-ligand tetranuclear clusters of the type [Cd4(EPh)x(E'R)10-x]2- and of the mixed-metal clusters [CdxZn4-x(SPh)10]2-

Cadmium-113 and carbon-13 nuclear magnetic resonance spectrometry of cadmium peptide complexes

The cadmium complexes of glycylglycine, glycylglycylglycine, glycyl-γ-aminobutyric acid and β-alanylglycine (β-Ala-Gly) have been investigated by 113 Cd and 13C nuclear magnetic resonance spectrometry. The minima observed in plots of the 113Cd chemical shift vs. pH are consistent with cadmium binding first at the car☐ylic site and then at the amino-group site. The chemical shift vs. pH profile for the β-Ala-Gly system is different from that for the other peptides, and is interpreted as suggesting formation of a five-membered chelate between Cd(II) and glycyl residues at the N-terminal groups and not at the C-terminal groups. The data further indicate that the NH groups of the peptide linkages are probably not involved in complexation with cadmium. Finally, a reported pH-dependent 113Cd resonance for parvalbumin has been reassigned.

Cadmium-Resistant Pseudomonas putida Synthesizes Novel Cadmium Proteins

Three cysteine-rich proteins of molecular weight 4000 to 7000, containing 4 to 7 gram atoms of cadmium, zinc, and copper per mole were isolated from Pseudomonas putida growing in 3 mM cadmium. The three proteins were induced during different phases of growth, and the smallest (molecular weight 3600; 3 gram atoms of cadmium) was released into the medium when the cells lysed. The results of amino acid analyses and of ultraviolet, circular dichroism, electron paramagnetic resonance, and cadmium-113 nuclear magnetic resonance spectroscopy suggest a novel cadmium(II)-zinc(II)-copper(I) cluster structure for the major protein.

Interaction of trifluoperazine and other drugs with calmodulin studied by cadmium-113 and fluorine-19 nuclear magnetic resonance

Interaction of trifluoperazine and other drugs with calmodulin studied by cadmium-113 and fluorine-19 nuclear magnetic resonance

Metal ion and drug binding to proteolytic fragments of calmodulin: proteolytic, cadmium-113, and proton nuclear magnetic resonance studies.

Tryptic fragmentation of Ca2+-saturated calmodulin (CaM) takes place mainly at Lys-77; however, proteolysis can occur instead at Arg-74 or Lys-75. This cleavage pattern results in the production of three peptides each of the amino- and carboxy-terminal halves of CaM of slightly different length. A purification scheme for the three carboxy-terminal half-peptides is reported. Proton nuclear magnetic resonance (1H NMR) studies of peptides comprising the amino- or carboxy-terminal half of CaM reveal the great structural similarity between these two proteolytic fragments and the intact protein. Since this was observed for the apoprotein as well as the Ca2+-saturated protein, this means that the two halves of the protein are independently folded. A comparison of the changes in the 1H NMR spectra observed for the intact protein and the fragments upon addition of Ca2+ clearly identified sites III and IV as the two high-affinity binding sites. Furthermore, addition of Ca2+ or Cd2+ induces qualitatively similar changes in the spectra, thus indicating that Cd2+ is a reliable replacement for Ca2+ in these studies. Subsequent 113Cd NMR studies of trifluoperazine (TFP) binding to tryptic and thrombic fragments of calmodulin revealed the presence of two distinct drug binding sites, one located in the amino-terminal half and one located in the carboxy-terminal half. The spectral changes, induced upon addition of the antipsychotic drug, were similar to those observed upon binding of TFP to intact calmodulin. The strongest TFP binding site is located in the carboxy-terminal half.

Manganese (II) electron spin resonance and cadmium-113 nuclear magnetic resonance evidence for the nature of the calcium binding site in alpha-lactalbumins.

Bovine and goat alpha-lactalbumins were substituted with 113Cd(II) or Mn(II) at the strong calcium site [Murakami, K., Andree, P.J., & Berliner, L.J. (1982) Biochemistry 21, 5488-5494] and studied by 113 Cd NMR and electron spin resonance. The 113Cd chemical shifts were in the -80 to -85 ppm range vs. Cd(ClO4)2, which was almost identical with that found for several nearly octahedral (oxygen-coordinated) calcium binding proteins such as calmodulin, parvalbumin, and troponin C. The electron spin resonance spectra of bound Mn(II)-alpha-lactalbumin complexes at 9 or 35 GHz were also confirmatory of a highly symmetric (cubic) environment around the Mn(II) with only slight distortions. The near identity of this site in alpha-lactalbumin to those of calcium binding proteins containing an "EF hand domain" was remarkable despite the absence of such a domain sequence in the alpha-lactalbumin structure.

Cadmium-113 Magnetic Resonance Spectroscopy

Cadmium-113 nuclear magnetic resonance spectroscopy has been used in studies of the structure and dynamics of inorganic and bioinorganic molecules. Chemical dynamics play an important role in the analysis of relaxation and chemical shift data. Naïve interpretations of relaxation data can be checked by performing these experiments at a variety of temperatures and magnetic field strengths. A combination of solid- and liquid-state nuclear magnetic resonance measurements can provide the user with unambiguous data on chemical shielding. These data can be used to characterize zinc and calcium ion binding sites in metalloproteins.

Cadmium-113 nuclear magnetic resonance studies of proteolytic fragments of calmodulin: assignment of strong and weak cation binding sites.

Proteolytic fragments of bovine testis calmodulin were obtained by limited proteolysis with trypsin or thrombin. Cadmium-113 NMR studies showed that the tryptic fragment encompassing Ca2+ binding domains III and IV (TR2C) gave rise to a spectrum identical with that of the native protein. Two thrombic fragments containing either domains I, II, and III [TM1-(1-106)] or the single domain IV [TM2-(107-148)] both gave rise to one broad resonance only. These data indicate that domains III and IV comprise the two high-affinity Ca2+ binding sites in intact calmodulin and that disturbance of the structural relationship between domain III and domain IV markedly reduces the affinity of these two sites for Ca2+ ions. These observations are discussed with respect to other published accounts concerning the sequence in which the four calcium domains in calmodulin are filled.

Cadmium-113 and carbon-13 nuclear magnetic resonance spectrometry of cadmium-amino acid complexes

Cadmium-113 and carbon-13 nuclear magnetic resonance spectrometry of cadmium-amino acid complexes

Cadmium-113 nuclear magnetic resonance spectroscopy. A probe for molecular structure and anisotropic motion in cadmium-substituted porphyrins

Cadmium-113 nuclear magnetic resonance spectroscopy. A probe for molecular structure and anisotropic motion in cadmium-substituted porphyrins