Metal Binding by Water-Soluble Polychelates and Implications for Agriculture

2011 ◽  
Vol 64 (12) ◽  
pp. 1593 ◽  
Author(s):  
Garry W. Warrender ◽  
Robert G. Gilbert
Keyword(s):  
Metal Ions ◽  
Atomic Absorption ◽  
Emulsion Polymerization ◽  
Atomic Absorption Spectroscopy ◽  
Metal Binding ◽  
Metal Ion ◽  
Agricultural Soils ◽  
Water Soluble ◽  
Aminosalicylic Acid ◽  
Chemical Binding

Means are developed to improve the metal ion delivery/remediation potential of polyacrylamides (PAMs), by incorporation of the co-monomer N-acryloyl-4-aminosalicylic acid. The polymers were synthesized by solution and inverse emulsion polymerization. The chemical binding of two soil micronutrients, Cu2+ and Fe3+, were investigated using atomic absorption spectroscopy. The modified PAM had an enhanced affinity for metal ions compared with conventional PAMs. This modified PAM has the potential as a delivery tool of plant micronutrients and stabilizers for agricultural soils undergoing intense irrigation. The same polymers may also provide a detoxifying effect in these applications where some micronutrient sources may be in excess and detrimental to productive agriculture.

scholarly journals Acylated Anthocyanins from Red Cabbage and Purple Sweet Potato Can Bind Metal Ions and Produce Stable Blue Colors

2021 ◽  
Vol 22 (9) ◽  
pp. 4551
Author(s):  
Julie-Anne Fenger ◽  
Gregory T. Sigurdson ◽  
Rebecca J. Robbins ◽  
Thomas M. Collins ◽  
M. Mónica Giusti ◽  
...  
Keyword(s):  
Metal Ions ◽  
Sweet Potato ◽  
Metal Binding ◽  
Metal Ion ◽  
High Resolution Mass Spectrometry ◽  
Large Set ◽  
Water Addition ◽  
Red Cabbage ◽  
Aluminum Ions ◽  
Purple Sweet Potato

Red cabbage (RC) and purple sweet potato (PSP) are naturally rich in acylated cyanidin glycosides that can bind metal ions and develop intramolecular π-stacking interactions between the cyanidin chromophore and the phenolic acyl residues. In this work, a large set of RC and PSP anthocyanins was investigated for its coloring properties in the presence of iron and aluminum ions. Although relatively modest, the structural differences between RC and PSP anthocyanins, i.e., the acylation site at the external glucose of the sophorosyl moiety (C2-OH for RC vs. C6-OH for PSP) and the presence of coordinating acyl groups (caffeoyl) in PSP anthocyanins only, made a large difference in the color expressed by their metal complexes. For instance, the Al3+-induced bathochromic shifts for RC anthocyanins reached ca. 50 nm at pH 6 and pH 7, vs. at best ca. 20 nm for PSP anthocyanins. With Fe2+ (quickly oxidized to Fe3+ in the complexes), the bathochromic shifts for RC anthocyanins were higher, i.e., up to ca. 90 nm at pH 7 and 110 nm at pH 5.7. A kinetic analysis at different metal/ligand molar ratios combined with an investigation by high-resolution mass spectrometry suggested the formation of metal–anthocyanin complexes of 1:1, 1:2, and 1:3 stoichiometries. Contrary to predictions based on steric hindrance, acylation by noncoordinating acyl residues favored metal binding and resulted in complexes having much higher molar absorption coefficients. Moreover, the competition between metal binding and water addition to the free ligands (leading to colorless forms) was less severe, although very dependent on the acylation site(s). Overall, anthocyanins from purple sweet potato, and even more from red cabbage, have a strong potential for development as food colorants expressing red to blue hues depending on pH and metal ion.

scholarly journals Crystallographic and X-ray absorption spectroscopic characterization of Helicobacter pylori UreE bound to Ni2+ and Zn2+ reveals a role for the disordered C-terminal arm in metal trafficking

2012 ◽  
Vol 441 (3) ◽  
pp. 1017-1035 ◽  
Author(s):  
Katarzyna Banaszak ◽  
Vlad Martin-Diaconescu ◽  
Matteo Bellucci ◽  
Barbara Zambelli ◽  
Wojciech Rypniewski ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Metal Ions ◽  
Metal Binding ◽  
Metal Ion ◽  
Mutual Influence ◽  
Accurate Information ◽  
Metal Ion Binding ◽  
X Ray ◽  
X Ray Absorption

The survival and growth of the pathogen Helicobacter pylori in the gastric acidic environment is ensured by the activity of urease, an enzyme containing two essential Ni2+ ions in the active site. The metallo-chaperone UreE facilitates in vivo Ni2+ insertion into the apoenzyme. Crystals of apo-HpUreE (H. pylori UreE) and its Ni2+- and Zn2+-bound forms were obtained from protein solutions in the absence and presence of the metal ions. The crystal structures of the homodimeric protein, determined at 2.00 Å (apo), 1.59 Å (Ni2+) and 2.52 Å (Zn2+) resolution, show the conserved proximal and solvent-exposed His102 residues from two adjacent monomers invariably involved in metal binding. The C-terminal regions of the apoprotein are disordered in the crystal, but acquire significant ordering in the presence of the metal ions due to the binding of His152. The analysis of X-ray absorption spectral data obtained using solutions of Ni2+- and Zn2+-bound HpUreE provided accurate information of the metal-ion environment in the absence of solid-state effects. These results reveal the role of the histidine residues at the protein C-terminus in metal-ion binding, and the mutual influence of protein framework and metal-ion stereo-electronic properties in establishing co-ordination number and geometry leading to metal selectivity.

Bildung wasserlöslicher Histidin-Platin- Komplexe aus metallischem Platin und Histidin / Formation of Water Soluble Histidine Platinum Complexes from Metallic Platinum and Histidine

1988 ◽  
Vol 43 (4) ◽  
pp. 499-500 ◽  
Author(s):  
Eva Ehrenstorfer-Schäfers ◽  
Helmut Hartl ◽  
Wolfgang Beck
Keyword(s):  
Atomic Absorption ◽  
Absorption Spectroscopy ◽  
Atomic Absorption Spectroscopy ◽  
Platinum Complex ◽  
Platinum Complexes ◽  
Water Soluble ◽  
Oxygen Atmosphere ◽  
Metallic Platinum

AbstractMetallic Platinum dissolves under oxygen atmosphere in aqueous histidine solution. About 0.1 to 0.3 μmol of a water soluble histidine platinum complex per ml solution have been found by atomic absorption spectroscopy.

scholarly journals Investigation of the nature of the two metal-binding sites in 5-aminolaevulinic acid dehydratase from Escherichia coli

1994 ◽  
Vol 300 (2) ◽  
pp. 373-381 ◽  
Author(s):  
P Spencer ◽  
P M Jordan
Keyword(s):  
Escherichia Coli ◽  
Metal Ions ◽  
Metal Binding ◽  
Binding Sites ◽  
Metal Ion ◽  
Protein Fluorescence ◽  
Metal Binding Sites ◽  
Aminolaevulinic Acid ◽  
Acid Dehydratase ◽  
Aminolaevulinic Acid Dehydratase

Two distinct metal-binding sites, termed alpha and beta, have been characterized in 5-aminolaevulinic acid dehydratase from Escherichia coli. The alpha-site binds a Zn2+ ion that is essential for catalytic activity. This site can also utilize other metal ions able to function as a Lewis acid in the reaction mechanism, such as Mg2+ or Co2+. The beta-site is exclusively a transition-metal-ion-binding site thought to be involved in protein conformation, although a metal bound at this site only appears to be essential for activity if Mg2+ is to be bound at the alpha-site. The alpha- and beta-sites may be distinguished from one another by their different abilities to bind divalent-metal ions at different pH values. The occupancy of the beta-site with Zn2+ results in a decrease of protein fluorescence at pH 6. Occupancy of the alpha- and beta-sites with Co2+ results in u.v.-visible spectral changes. Spectroscopic studies with Co2+ have tentatively identified three cysteine residues at the beta-site and one at the alpha-site. Reaction with N-ethyl[14C]maleimide preferentially labels cysteine-130 at the alpha-site when Co2+ occupies the beta-site.

scholarly journals A trapped human PPM1A–phosphopeptide complex reveals structural features critical for regulation of PPM protein phosphatase activity

2018 ◽  
Vol 293 (21) ◽  
pp. 7993-8008 ◽  
Author(s):  
Subrata Debnath ◽  
Dalibor Kosek ◽  
Harichandra D. Tagad ◽  
Stewart R. Durell ◽  
Daniel H. Appella ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Metal Ions ◽  
Active Site ◽  
Metal Binding ◽  
Metal Ion ◽  
Catalytic Domain ◽  
Protein Phosphatases ◽  
Random Order ◽  
Structural Features

Metal-dependent protein phosphatases (PPM) are evolutionarily unrelated to other serine/threonine protein phosphatases and are characterized by their requirement for supplementation with millimolar concentrations of Mg2+ or Mn2+ ions for activity in vitro. The crystal structure of human PPM1A (also known as PP2Cα), the first PPM structure determined, displays two tightly bound Mn2+ ions in the active site and a small subdomain, termed the Flap, located adjacent to the active site. Some recent crystal structures of bacterial or plant PPM phosphatases have disclosed two tightly bound metal ions and an additional third metal ion in the active site. Here, the crystal structure of the catalytic domain of human PPM1A, PPM1Acat, complexed with a cyclic phosphopeptide, c(MpSIpYVA), a cyclized variant of the activation loop of p38 MAPK (a physiological substrate of PPM1A), revealed three metal ions in the active site. The PPM1Acat D146E–c(MpSIpYVA) complex confirmed the presence of the anticipated third metal ion in the active site of metazoan PPM phosphatases. Biophysical and computational methods suggested that complex formation results in a slightly more compact solution conformation through reduced conformational flexibility of the Flap subdomain. We also observed that the position of the substrate in the active site allows solvent access to the labile third metal-binding site. Enzyme kinetics of PPM1Acat toward a phosphopeptide substrate supported a random-order, bi-substrate mechanism, with substantial interaction between the bound substrate and the labile metal ion. This work illuminates the structural and thermodynamic basis of an innate mechanism regulating the activity of PPM phosphatases.

Metal ion complexation by soft nanoparticles: the effect of Ca2+ on electrostatic and chemical contributions to the Eigen-type reaction rate

2015 ◽  
Vol 12 (2) ◽  
pp. 130 ◽  
Author(s):  
Raewyn M. Town
Keyword(s):  
Humic Acid ◽  
Trace Metal ◽  
Metal Ions ◽  
Electrostatic Field ◽  
Metal Binding ◽  
Metal Ion ◽  
Bulk Solution ◽  
Trace Metal Ions ◽  
Charged Nanoparticles ◽  
Soft Nanoparticles

Environmental context The speciation of trace metals in the environment is often dominated by complexation with natural organic matter such as humic acid. Humic acid is a negatively charged soft nanoparticle and its electrostatic properties play an important role in its reactivity with metal ions. The presence of major cations, such as Ca2+, can decrease the effective negative charge in the humic acid particle body and thus modify the chemodynamics of its interactions with trace metal ions. Abstract The effect of Ca2+ on the chemodynamics of PbII complexation by humic acid (HA) is interpreted in terms of theory for permeable charged nanoparticles. The effect of the electrostatic field of a negatively charged nanoparticle on its rate of association with metal cations is governed by the interplay of (i) conductive enhancement of the diffusion of cations from the medium to the particle and (ii) ionic Boltzmann equilibration with the bulk solution leading to accumulation of cations in the particle body. Calcium ions accumulate electrostatically within the HA body and thus lower the magnitude of the negative potential in the particle. For the case where trace metal complexation takes place in a medium in which the particulate electrostatic field is set by pre-equilibration in the electrolyte, the lability of Pb-HA complexes is found to be significantly increased in Ca2+-containing electrolyte, consistent with the predicted change in particle potential. Furthermore, the rate-limiting step changes from diffusive supply to the particle body in a 1–1 electrolyte, to inner-sphere complexation in a 2–1 electrolyte. The results provide insights into the electrostatic and covalent contributions to the thermodynamics and kinetics of trace metal binding by soft nanoparticles.

Quantitative Determination of Cadmium in Water-Soluble Color Additives by Atomic Absorption Spectroscopy

1972 ◽  
Vol 55 (5) ◽  
pp. 1145-1149
Author(s):  
Lueangier Moten
Keyword(s):  
Aqueous Solutions ◽  
Quantitative Determination ◽  
Atomic Absorption ◽  
Absorption Spectroscopy ◽  
Atomic Absorption Spectroscopy ◽  
Quantitative Method ◽  
Water Soluble ◽  
Low Levels ◽  
Absorption Measurements

Abstract A quantitative method is presented for the determination of cadmium at low levels (5–20 ppm) in water-soluble color additives by atomic absorption spectroscopy. Absorption measurements were made on aqueous solutions of typical color additives to which known amounts of cadmium had been added. The method requires no pretreatment of sample and should be applicable to all water-soluble color additives.

Effect of Acid Pretreatment on Photocatalysis Bleaching

2012 ◽  
Vol 490-495 ◽  
pp. 3231-3236
Author(s):  
Yan Ping Lei ◽  
Yao Li ◽  
Bin Nong ◽  
Dong Mei Huang
Keyword(s):  
Metal Ions ◽  
Atomic Absorption ◽  
Absorption Spectroscopy ◽  
Atomic Absorption Spectroscopy ◽  
Spectroscopy Analysis ◽  
Acid Pretreatment ◽  
Removal Rates ◽  
Bleached Pulp ◽  
Before And After ◽  
Maximum Removal

After H2SO4 pretreatment, in unbleached pulps the content of metal ions Mg2+、Mn2+、Fe3+、Zn2+ and Cu2+ are reduced in varying degrees by atomic absorption spectroscopy analysis, among the ions, the maximum removal rates are Cu2+ and Mg2+. And when the added amount of H2SO4 is 1.5%, the removal result of metal ions is the best. After acid pretreatment, the pulp’s brightness has been increased about 3.8%ISO-5%ISO, the pulp’s hardness has been reduced by 0.7%-1.0%, the pulp’s viscosity has been kept well. Besides, when the added dosage of H2SO4 is 1.0%, the increasing of whiteness and the decreasing of hardness are the greatest. Through the contrast research of photocatalysis bleaching to the two pulps of before and after acid pretreatment, the results has been found that the brightness of bleached pulp been decreased about 2.3%ISO-3.5%ISO, and the decreasing rates of hardness and viscosity respectively are almost the same after H2SO4 pretreatment.

scholarly journals Computational approaches for de novo design and redesign of metal-binding sites on proteins

2017 ◽  
Vol 37 (2) ◽  
Author(s):  
Gunseli Bayram Akcapinar ◽  
Osman Ugur Sezerman
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Binding Sites ◽  
Metal Ion ◽  
De Novo ◽  
De Novo Design ◽  
Ion Binding ◽  
Chemical Transformations ◽  
Metal Ion Binding ◽  
Metal Binding Sites

Metal ions play pivotal roles in protein structure, function and stability. The functional and structural diversity of proteins in nature expanded with the incorporation of metal ions or clusters in proteins. Approximately one-third of these proteins in the databases contain metal ions. Many biological and chemical processes in nature involve metal ion-binding proteins, aka metalloproteins. Many cellular reactions that underpin life require metalloproteins. Most of the remarkable, complex chemical transformations are catalysed by metalloenzymes. Realization of the importance of metal-binding sites in a variety of cellular events led to the advancement of various computational methods for their prediction and characterization. Furthermore, as structural and functional knowledgebase about metalloproteins is expanding with advances in computational and experimental fields, the focus of the research is now shifting towards de novo design and redesign of metalloproteins to extend nature’s own diversity beyond its limits. In this review, we will focus on the computational toolbox for prediction of metal ion-binding sites, de novo metalloprotein design and redesign. We will also give examples of tailor-made artificial metalloproteins designed with the computational toolbox.

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