A study on the metal binding of humic acid by multitracer technique

2006 ◽  
Vol 94 (1) ◽  
Author(s):  
Zheng Chang ◽  
Shizuko Ambe ◽  
Kazuya Takahashi ◽  
Fumitoshi Ambe
Keyword(s):  
Humic Acid ◽  
Metal Ions ◽  
Small Molecule ◽  
Metal Binding ◽  
Technical Problems ◽  
Slow Diffusion ◽  
Dialysis Membranes

SummaryA method combining radioactive ‘multitracer’ and dialysis techniques was developed to study the binding of multiple metal ions to humic acid (HA). Technical problems such as the leakage of small-molecule HA segment and the slow diffusion of metal ions through the dialysis membranes were examined. Under the condition of pH = 4.0,

scholarly journals Isolation of humic acid from oxidized lignite and complexation with metal cations

2017 ◽  
Vol 71 (4) ◽  
pp. 319-327
Author(s):  
Benjamin Catovic ◽  
Minela Sisic ◽  
Majda Srabovic ◽  
Melita Huremovic
Keyword(s):  
Humic Acid ◽  
Metal Ions ◽  
Humic Acids ◽  
Metal Binding ◽  
Base Material ◽  
Metal Cations ◽  
Biological Properties ◽  
Metal Nitrate ◽  
Chemical Difference ◽  
The Difference

Lignite is brown coal, which in its composition contains humic acids. Humic acids are produced by coal combustion, which leads to the enrichment of coal humic acids. Lignite, from the opet pit mine Sikulje, lignite ore ?Kreka?, Bosnia and Herzegovina, was fragmented and sieved to the appropriate size and used as a base material. The isolation of humic acid was carried out from pre-oxidized and dried lignite after which it was refined. Identification thus obtained humic acids was carried out by FTIR spectroscopy and its characterization of UV analysis which is determined by optical density of isolated humic acid and its complexation with metal cations. Data obtained by FTIR spectroscopic analysis of isolated humic acids show no significant structural and chemical difference in relation to the spectrum obtained for standard humic acids (Sigma Aldrich). UV analysis showed that isolated and standard humic acid have E4/E6 ratio in an appropriate range of 3?5, which indicates the presence of a large number of aliphatic structure. Based on the degree of humification was found that the isolated humic acids belong to the type B standard while humic acids belong to type A. The most important property of the humic substances is the ability to interact with the metal ions forming soluble or insoluble complexes which possess different chemical and biological properties and stability. The nature of the complex between humic acid and metal cation derived from the heterogeneous, polyelectric and polydispersive character humic acids that occurs due to the presence of a large number of functional groups. Complexation of humic acid is carried out with different concentrations of metal nitrate solutions and at different pH values. Different amounts of humic acids were used for the complexation. The amount of the free metal ions was measured with the ICP-OES methode. The data were also statistically analyzed with ANOVA. The results showed that increasing the pH reduces the concentration of metal ions adsorbed on humic acid and by increasing the concentrations and amounts of metal humic acid that power increases. On the basis of the difference in absorbance between metals and humic acids can be said that there is an interaction between the metal and the ligand and is based on absorbance values obtained can be determine the next set of metal binding to humic acids Pb>Zn>Ni>Cu.

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.

scholarly journals Deferoxamine B: A Natural, Excellent and Versatile Metal Chelator

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3255
Author(s):  
Denise Bellotti ◽  
Maurizio Remelli
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Chelation Therapy ◽  
Iron Chelation ◽  
Binding Ability ◽  
Complex Formation Equilibria ◽  
Metal Chelator ◽  
The Past ◽  
Formation Equilibria ◽  
Terminal Amino

Deferoxamine B is an outstanding molecule which has been widely studied in the past decade for its ability to bind iron and many other metal ions. The versatility of this metal chelator makes it suitable for a number of medicinal and analytical applications, from the well-known iron chelation therapy to the most recent use in sensor devices. The three bidentate hydroxamic functional groups of deferoxamine B are the centerpiece of its metal binding ability, which allows the formation of stable complexes with many transition, lanthanoid and actinoid metal ions. In addition to the ferric ion, in fact, more than 20 different metal complexes of deferoxamine b have been characterized in terms of their chemical speciation in solution. In addition, the availability of a terminal amino group, most often not involved in complexation, opens the way to deferoxamine B modification and functionalization. This review aims to collect and summarize the available data concerning the complex-formation equilibria in solutions of deferoxamine B with different metal ions. A general overview of the progress of its applications over the past decade is also discussed, including the treatment of iron overload-associated diseases, its clinical use against cancer and neurodegenerative disorders and its role as a diagnostic tool.

scholarly journals Metal Binding Proteins

Encyclopedia ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 261-292
Author(s):  
Eugene A. Permyakov
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Transition Metal Ions ◽  
Short Review ◽  
Sodium Potassium ◽  
Physical Chemical ◽  
Physiological Properties ◽  
Cell Processes ◽  
Living Organisms ◽  
Potassium Magnesium

Metal ions play several major roles in proteins: structural, regulatory, and enzymatic. The binding of some metal ions increase stability of proteins or protein domains. Some metal ions can regulate various cell processes being first, second, or third messengers. Some metal ions, especially transition metal ions, take part in catalysis in many enzymes. From ten to twelve metals are vitally important for activity of living organisms: sodium, potassium, magnesium, calcium, manganese, iron, cobalt, zinc, nickel, vanadium, molybdenum, and tungsten. This short review is devoted to structural, physical, chemical, and physiological properties of proteins, which specifically bind these metal cations.

scholarly journals Regulation of divalent metal ions to the aggregation and membrane damage of human islet amyloid polypeptide oligomers

RSC Advances ◽  
2021 ◽  
Vol 11 (21) ◽  
pp. 12815-12825
Author(s):  
Yajie Wang ◽  
Feihong Meng ◽  
Tong Lu ◽  
Chunyun Wang ◽  
Fei Li
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Membrane Damage ◽  
Islet Amyloid Polypeptide ◽  
Divalent Metal ◽  
Human Islet ◽  
Divalent Metal Ions ◽  
Islet Amyloid ◽  
Induced Membrane ◽  
Human Islet Amyloid Polypeptide

Their is a counteraction between a decrease in the disruptive ability of metal-associated oligomer species and an increase in the quantity of oligomers promoted by the metal binding in the activity of hIAPP induced membrane damage.

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.

scholarly journals An improved assay for bacterial methane mono-oxygenase: some properties of the enzyme from Methylomonas methanica

1975 ◽  
Vol 151 (2) ◽  
pp. 459-462 ◽  
Author(s):  
J Colby ◽  
H Dalton ◽  
R Whittenbury
Keyword(s):  
Metal Ions ◽  
Methane Oxidation ◽  
Metal Binding ◽  
Methylomonas Methanica

Extracts of Methylomonas methanica catalyse the O2-and NAD(P)H-dependent disappearance of bromomethane. The activity is unstable at 2 degrees C but is stable at --70 degrees C for several weeks. Bromomethane mono-oxygenase is particulate and is inhibited by metal-binding reagents, by compounds SKF 525A and Lilly 53325, by some metal ions and by acetylene. Evidence is presented that indicates that bromomethane mono-oxygenase is the enzyme responsible for methane oxidation in vivo.

Biodegradation of phorate by bacterial strains in the presence of humic acid and metal ions

2021 ◽  
Author(s):  
Simranjeet Singh ◽  
Vijay Kumar ◽  
Amith G. Anil ◽  
Romina Romero ◽  
Praveen C. Ramamurthy ◽  
...  
Keyword(s):  
Humic Acid ◽  
Metal Ions ◽  
Bacterial Strains

scholarly journals Binding of Gd3+to the neuronal signalling protein calexcitin identifies an exchangeable Ca2+-binding site

2016 ◽  
Vol 72 (4) ◽  
pp. 276-281
Author(s):  
Lucas Chataigner ◽  
Jingxu Guo ◽  
Peter T. Erskine ◽  
Alun R. Coker ◽  
Steve P. Wood ◽  
...  
Keyword(s):  
Metal Ions ◽  
Binding Site ◽  
Metal Binding ◽  
Calcium Signalling ◽  
Specific Protein ◽  
Metal Binding Sites ◽  
Calcium Sensing ◽  
Neuronal Signalling ◽  
Ef Hand ◽  
Ef Hands

Calexcitin was first identified in the marine snailHermissenda crassicornisas a neuronal-specific protein that becomes upregulated and phosphorylated in associative learning. Calexcitin possesses four EF-hand motifs, but only the first three (EF-1 to EF-3) are involved in binding metal ions. Past work has indicated that under physiological conditions EF-1 and EF-2 bind Mg2+and Ca2+, while EF-3 is likely to bind only Ca2+. The fourth EF-hand is nonfunctional owing to a lack of key metal-binding residues. The aim of this study was to use a crystallographic approach to determine which of the three metal-binding sites of calexcitin is most readily replaced by exogenous metal ions, potentially shedding light on which of the EF-hands play a `sensory' role in neuronal calcium signalling. By co-crystallizing recombinant calexcitin with equimolar Gd3+in the presence of trace Ca2+, EF-1 was shown to become fully occupied by Gd3+ions, while the other two sites remain fully occupied by Ca2+. The structure of the Gd3+–calexcitin complex has been refined to anRfactor of 21.5% and anRfreeof 30.4% at 2.2 Å resolution. These findings suggest that EF-1 of calexcitin is the Ca2+-binding site with the lowest selectivity for Ca2+, and the implications of this finding for calcium sensing in neuronal signalling pathways are discussed.

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