Calcium-chelating peptides from rabbit bone collagen:characterization,identification and mechanism elucidation

This study aimed to characterize and identify calcium-chelating peptides from rabbit bone collagen and explore the underlying chelating mechanism.Collagen peptides and calcium were extracted from rabbit bone by instant ejection steam explosion(ICSE)combined with enzymatic hydrolysis,followed by chelation reaction to prepare rabbit bone peptide-calcium chelate(RBCP-Ca).The chelating sites were further analyzed by liquid chromatography-tandem mass(LC-MS/MS)spectrometry while the chelating mechanism and binding modes were investigated.The structural characterization revealed that RBCP successfully chelated with calcium ions.Furthermore,LC-MS/MS analysis indicated that the binding sites included both acidic amino acids(Asp and Glu)and basic amino acids(Lys and Arg),Interestingly,three binding modes,namely Inter-Linking,Loop-Linking and Mono-Linking were for the first time found,while Inter-Linking mode accounted for the highest proportion(75.1%),suggesting that chelation of calcium ions frequently occurred between two peptides.Overall,this study provides a theoretical basis for the elucidation of chelation mechanism of calcium-chelating peptides.

Polarizable Additive with Intermediate Chelation Strength for Stable Aqueous Zinc‑Ion Batteries

Aqueous zinc-ion batteries are promising due to inherent safety,low cost,low toxicity,and high volumetric capacity.However,issues of dendrites and side reactions between zinc metal anode and the electrolyte need to be solved for extended storage and cycle life.Here,we proposed that an electrolyte additive with an intermediate chelation strength of zinc ion—strong enough to exclude water molecules from the zinc metal-electrolyte interface and not too strong to cause a significant energy barrier for zinc ion dissociation—can benefit the electrochemical stability by suppressing hydrogen evolution reaction,overpotential growth,and den-drite formation.Penta-sodium diethylene-triaminepentaacetic acid salt was selected for such a purpose.It has a suitable chelating ability in aqueous solutions to adjust solvation sheath and can be readily polarized under electrical loading conditions to further improve the passivation.Zn||Zn symmetric cells can be stably operated over 3500 h at 1 mA cm^(-2).Zn||NH4V4O10 full cells with the additive show great cycling stability with 84.6%capacity retention after 500 cycles at 1 A g^(-1).Since the additive not only reduces H2 evolution and corrosion but also modifies Zn2+diffusion and deposition,highlyreversible Zn electrodes can be achieved as verified by the experimental results.Our work offers a practical approach to the logical design of reliable electrolytes for high-performance aqueous batteries.

Role of copper chelating agents: between old applications and new perspectives in neuroscience

The role of copper element has been an increasingly relevant topic in recent years in the fields of human and animal health, for both the study of new drugs and innovative food and feed supplements. This metal plays an important role in the central nervous system, where it is associated with glutamatergic signaling, and it is widely involved in inflammatory processes. Thus, diseases involving copper(Ⅱ) dyshomeostasis often have neurological symptoms, as exemplified by Alzheimer's and other diseases(such as Parkinson's and Wilson's diseases). Moreover, imbalanced copper ion concentrations have also been associated with diabetes and certain types of cancer, including glioma. In this paper, we propose a comprehensive overview of recent results that show the importance of these metal ions in several pathologies, mainly Alzheimer's disease, through the lens of the development and use of copper chelators as research compounds and potential therapeutics if included in multi-target hybrid drugs. Seeing how copper homeostasis is important for the well-being of animals as well as humans, we shortly describe the state of the art regarding the effects of copper and its chelators in agriculture, livestock rearing, and aquaculture, as ingredients for the formulation of feed supplements as well as to prevent the effects of pollution on animal productions.

Electrode/Electrolyte Interfacial Chemistry Modulated by Chelating Effect for High-Performance Zinc Anode

Although Zn metal has been regarded as the most promising anode for aqueous batteries,its practical application is still restricted by side reactions and dendrite growth.Herein,an in-situ solid electrolyte interphase(SEI)film formed on the interface of electrode/electrolyte during the plating/stripping of zinc anodes by introducing trace amounts of multidentate ligand sodium diethyldithiocarbamate(DDTC)additive into 1 M ZnSO_(4).The synergistic effect of in-situ solid electrolyte interphase forming and chelate effect endows Zn^(2+)with uniform and rapid interface-diffusion kinetics against dendrite growth and surface side reactions.As a result,the Zn anode in 1 M ZnSO_(4)+DDTC electrolytes displays an ultra-high coulombic efficiency of 99.5%and cycling stability(more than 2000 h),especially at high current density(more than 600 cycles at 40 mA cm^(-2)).Moreover,the Zn//MnO_(2)full cells in the ZnSO_(4)+DDTC electrolyte exhibit outstanding cyclic stability(with 98.6%capacity retention after 2000 cycles at 10 C).This electrode/electrolyte interfacial chemistry modulated strategy provides new insight into enhancing zinc anode stability for high-performance aqueous zinc batteries.

Superior growth performance in broiler chicks fed chelated compared to inorganic zinc in presence of elevated dietary copper

Background： The goal of this study was to compare the antagonism of elevated dietary Cu （250 mg/kg） from CuS04 on three different Zn sources （ZnS04. H20; [Zn bis（-2-hydroxy-4-（methylthio）butanoic acid）], Zn（HMTBa）2 a chelated Zn methionine hydroxy analogue; and Zn-Methionine）, as measured using multiple indices of animal performance in ROSS 308 broilers. Methods： Three experiments were conducted in broiler chicks fed a semi-purified diet. All birds were fed a Zn-deficient diet （8.5 mg/kg diet） for 1 wk, and then provided with the experimental diets for 2 wks. Results： Experiment 1 was a 2 x 2 factorial design with two levels of Cu （8 vs. 250 mg/kg diet from CuSO4） and two Zn sources at 30 mg/kg [ZnSO4. H20 vs. Zn（HMTBa）2]. Elevated Cu impaired growth performance only in birds fed ZnSO4. Compared to ZnSO4. H20, Zn（HMTBa）2 improved feed intake （12 %; P 〈 0.001） and weight gain （12 %, P 〈 0.001） and the benefits were more pronounced in the presence of 250 mg/kg diet Cu. Experiment 2 was a dose titration of ZnSO4- H20 and Zn（HMTBa）2 at 30, 4,5, 60, and 75 mg/kg diet in the presence of 250 mg/kg CuSO4. Feed：gain was decreased and tibia Zn was increased with increasing Zn levels from 30 to 75 mg/kg. Birds fed Zn（HMTBa）2 consumed more food and gained more weight compared to birds fed ZnSO4, especially at lower supplementation levels （30 and 45 mg/kg; interaction P 〈 0,05）. Experiment 3 compared two organic Zn sources （Zn（HMTBa）2 vs. Zn-Methionine） at 30 mg/kg with or without 250 mg/kg CuSO4. No interactions were observed between Zn sources and Cu levels on performance or tissue mineral concentrations. High dietary Cu decreased weight gain （P 〈 0.01）. Tibia Cu and liver Cu were significantly increased with 250 mg/kg dietary Cu supplementation （P 〈 0.01）. No difference was observed between the two Zn sources. Conclusions： Dietary 250 mg/kg Cu significantly impaired feed intake and weight gain in birds fed ZnSO4. H20, but had less impact in birds fed Zn（HMTBa）2. No difference was observed between the two organic zinc sources These results are consistent with the hypothesis that chelated organic Zn is better utilized than inorganic zinc in the presence of elevated Cu.

Progress on Study of Luminescence of Rare Earth Organic Chelates

Based on the investigation of the luminescence of a series of rare earth organic chelates, some relationships between luminescence and the structure of the chelates were proposed: the intensity of sensitized luminescence of central lanthanide ions(Ln 3+ ) in a rare earth organic chelate depends on (1)the suitability of the energy gap between the excited triplet energy level of the ligands and the lowest excited energy level of Ln 3+ ions; (2)the rigidity and planarity of the structure of the chelate molecule; (3)the existence of a suitable secondary ligand which may increase rigidity and the stability of the chelate molecule; and (4) the existence of a suitable π conjugated system in the chelate molecule. According to the above relationships, 25 novel organic ligands were designed and synthesized, and their lanthanide chelates were prepared. Investigation of the photoluminescence for the new chelates shows that some of the chelates are strongly luminescent, and are applied to fluoroimmunoassay for determination of human immunoglobulin(IgG), to preparation of fluorescent plastics, and to determination of growth hormone for plants. Two novel spectroscopy probe techniques for structure of coordination compounds and biological molecules were proposed and developed based on vibronic spectroscopy of Tb 3+ complexes and fluorescence of Ce 3+ .

Effect of Feeding a Combination of Zinc, Manganese and Copper Methionine Chelates of Early Lactation High Producing Dairy Cow

The objective of the study was to compare the effect of feeding mixed chelated minerals (Mn, Cu and Zn) methionine on dairy cow productive performance and milk yield and its components. The trial was conducted with dairy cows across various stage of lactation. The experimental treatments include chelated minerals (15 mg Zn as Zn Met, 20 mg Mn as Mn Met, 10 mg Cu as Cu Met). Inorganic mixture contains (15 mg Zn as ZnSO4, 20 mg Mn as MnSO4, 10 mg Cu as CuSO4) in sulphate forms. The experiment was commenced in the dry period of cows, 6 weeks before calving, and after calving the first three months of lactation was taken into consideration. Milk samples were collected from each cow evening and morning for estimation of milk yield production. The inorganic metals caused a significant decline (P < 0.05) in digestibility coefficients, nutritive value, nitrogen utilization, Cell wall constituents, total VFA’s, rumen volume, microbial and nitrogen synthesis compared to the organic metals. The treated group (chelated minerals) improved the milk yield, and the milk fat percentage of animals across various stages of lactation as compared to inorganic minerals treated group of animals, and no significant differences were observed among groups concerning the entire blood constituent.

STUDY ON THERMAL DECOMPOSITION KINETICS OF URUSHIOL METAL CHELATE POLYMERS

The thermal decomposition kinetics of urushiol-Cu, urushiol-Nd and urushiol-Ti chelatepolymers has been studied by non-isothermal thermogravimetry. The results suggest that thethermal decomposition kinetics of three chelate polymers are all of first order. Their averageactivation energy values of the thermal decomposition calculated by Ozawa-(I) method are 110,79, 136. 98 and 163. 64 kJ mol^(-1) respectively, which increase linearly with the metal valence of themetal chelate polymers

Structure of Copper Chelate of 2-Hydroxy-4-methylthiobutanoic Acid as Trace Mineral Additive in Animal Feeding

The chelate complex of Cu2＋ with 2-hydroxy-（4-methylthio）butanoate（MHA-H, the anion derived from the so-called methionine hydroxy-analogue, largely used in animal nutrition as a source of methionine, MHA） is an efficient, bioavailable trace mineral additive for animal feeding. The structure of MHA-H copper chelate was investigated by single-crystal X-ray diffraction. The crystal structure（C10H18Cu O6S2, 1, monoclinic, space group P21/c, Z = 2, a = 16.158（4）, b = 4.9733（12）, c = 9.159（2） ？, β = 104.786（4）°） exhibits that two MHA-H ligands coordinate with a CuII ion to form a square-planar environment completed to an octahedron through interaction with carbonyl oxygens of neighboring molecules, which expand to constitute a two-dimensional sheet coordination network. And a separation between the hydrophilic and lipophilic moieties like micelles was found in the packing structure. X-ray powder diffraction and thermogravimetric analysis were used to study the phase purity of the bulk sample and thermostability of complex 1, respectively.

Studies on the Hydrogen Bonding Network Structures of Amino-konjacglucomannan-zinc Chelate

Amino-Konjacglucomannan （NH2-KGM） was prepared through the reaction of ammonium hydroxide with KGM by ultrasonic. The influence of amount of ammonium hydroxide, concentration of KGM and ultrasonic time on the extent of amination was studied. Then, NH2-KGM and zinc sulfate were used as materials for the preparation of NH2-KGM-Zn complex. The results indicated that the extent of amination increases with increasing the ammonium hydroxide. The optimum concentration of KGM and ultrasonic time are 0.3% and 75 rain respectively. IR showed KGM is successfully aminated and NH2-KGM forms stable complex with zinc（II ）. The hydrogen bonding network structures of NH2-KGM-Zn are more stable and the key linking points of hydrogen bonding network are at the OH（6） and 0（3） positions of mannose and OH（2） of glucose and 0（3） of mannose on the KGM ring. It is more favorable for NH2-KGM-Zn to form intermolecular hydrogen bonds between KGM.

Selection of Chelated Fe(Ⅲ)/Fe(Ⅱ) Catalytic Oxidation Agents for Desulfurization Based on Iron Complexation Method

Optimization of factors influencing the experiments on reactions involving 8 different chelating agents and soluble Fe(III)/Fe(II) salts was carried out to yield chelated iron complexes. A combination of optimized influencing factors has resulted in a Fe chelating capacity of the iron-based desulfurization solution to be equal to 6.83—13.56 g/L at a redox potential of 0.185—0.3. The desulfurization performance of Fe(III)/Fe(II) chelating agents was investigated on a simulated sulfur-containing industrial gas composed of H2 S and N2 in a cross-flow rotating packed bed. Test results have revealed that the proposed iron-based desulfurization solution showed a sulfur removal efficiency of over 99% along with a Fe chelating capacity exceeding 1.35 g/L. This desulfurization technology which has practical application prospect is currently in the phase of commercial scale-up study.

Synthesis and Characterization of 2-Decyl-DTPA and Its Gd(Ⅲ) Chelate

The present paper covers the synthesis and the characterization of ligand 2-decyl-3,6,9-tris(carboxymethyl)-3,6,9-triazaundecan-1,11-dioic acid,H_5L,and its Gd(Ⅲ) chelate. The protonation constants for H_5L(lg K H_ i =10.90,8.50,4.55,2.92,2.20) and the stability constant for GdL 2- (lg K _ GdL 2- =22.80) were determined by means of potentiometric titration. They are similar to the corresponding values of DTPA and Gd-DTPA,respectively. The results obtained show that the basicity of the ligand and the stability constant of its Gd(Ⅲ) chelate are not obviously altered after the introduction of a linear chain decyl group into the terminal acetic acid residue of DTPA. The Gd(Ⅲ) chelate may be a potential contrast agent with liver-specificity for magnetic resonance imaging(MRI).

Air-Stable Ultrabright Inverted Organic Light-Emitting Devices with Metal Ion-Chelated Polymer Injection Layer

Here,this work presents an air-stable ultrabright inverted organic lightemitting device(OLED)by using zinc ionchelated polyethylenimine(PEI)as electron injection layer.The zinc chelation is demonstrated to increase the conductivity of the PEI by three orders of magnitude and passivate the polar amine groups.With these physicochemical properties,the inverted OLED shows a record-high external quantum efficiency of 10.0% at a high brightness of 45,610 cd m^(-2) and can deliver a maximum brightness of 121,865 cd m^(-2).Besides,the inverted OLED is also demonstrated to possess an excellent air stability(humidity,35%)with a half-brightness operating time of 541 h@1000 cd m^(-2) without any protection nor encapsulation.

Optimization of High-Gravity Chelated Iron Process for Removing H_2S Based on Response Surface Methodology

By using a mixture of N2 and H2S as the simulated APG(associated petroleum gas), the desulfurization experiment was performed in a cross-flow rotating packed bed(RPB) based on the chelated iron oxidation-reduction method. In order to determine the operating conditions of the system, the effects of the concentration of Fe3+ ions(ranging from 0.1 to 0.2 mol/L), the liquid-gas volume ratio(ranging from 15 to 25 L/m3) and the high gravity factor(ranging from 36 to 126) on the removal of H2 S were studied by means of the Box-Behnken design(BBD) under response surface methodology(RSM). The overall results have demonstrated that the BBD with an experimental design can be used effectively in the optimization of the desulfurization process. The optimal conditions based on both individualized and combined responses(at a Fe3+ ion concentration of 0.16 mol/L, a liquid-gas volume ratio of 20.67 L/m3 and a high gravity factor of 87) were found. Under this optimum condition, the desulfurization efficiency could reach 98.81% when the H2 S concentration was 7 g/m3 in APG. In this work, the sulfur product was analyzed by X-ray diffraction(XRD), scanning electron microscopy(SEM) and the energy dispersive X-ray spectrometer(EDX). The results of analysis show that the sulfur is made of the high-purity orthorhombic crystals, which are advantageous to environmental conservation.

Rapid Regeneration of Chelated Iron Desulfurization Solution Using Electrochemical Reactor with Rotating Cylindrical Electrodes

A new electrochemical reactor with rotating cylindrical electrodes was designed and used to increase the regeneration efficiency of chelated iron desulfurization solution.The influence of operating parameters,such as the rotation speed of electrode,voltage,and inlet air and liquid flow rates,on the regeneration rate was investigated.Compared with the traditional tank-type reactor,the regeneration rate with the new electrochemical reactor was increased significantly.Under the optimum conditions,the regeneration rate was increased from 45.3%to 84.8%.Experimental results of continuous operation indicated that the new electrochemical regeneration method had some merits including higher regeneration efficiency,smaller equipment size and good stability in operation.

Modification on Synthesis of Mixed Ligand Chelates by Using Di- and Trivalent Transition Metal Ions with Schiff Base as Primary Ligand

New mixed ligand chelates synthesized from di-and trivalent metal ions (Cr, Co, Ni, and Cu ions) and Schiff base (L1) resulted from the condensation of 4-dimethylaminobenzaldehyde with 2-aminophenol as primary ligand, whereas 2-nitroaniline (L2) represents the secondary ligand in a molar ratio of M:L1:L2 [1:1:1]. The synthesized Schiff base and chelates have been characterized by using several tools, such as, elemental analysis, molar conductivity, magnetic moment measurements, infrared and electronic spectra. The mass spectra of the ligands and Ni(II) chelate were used to justify the process of modification, as well as, the electron paramagnetic resonance spectrum which was carried out for Cu(II) chelate all in order to elucidate the chemical and geometrical structure of the chelates. On the basis of the obtained data, the geometry of the products was proposed for all the chelates.

LABELING OF PROTEIN WITH A NEW EUROPIUM CHELATE OF 5-CHLOROSULFOYL-2-THENOYLTRIFLUOROACETONE(CTTA)AND APPLICATION TO IMMUNOASSAY

We describe for the first time the synthesis and the optimal conditions for protein labeling with a new fluorescent probe,5-chlorosulfoyl-2-thenoyltrifluoroacetone(CTTA),whicb forms a highly fluorescent conplex with Eu^(3+) when conjugated to protein.The labeled proteins were characterized by absorbance and fluorescence measurements and the effect of labeling on the biological activity of sone proteins was also studied.It is shown that the new label is suitable for applications in time-resolved fluoroimmunoassay.

PREPARATION AND CLEAVAGE MECHANISM OF CHELATES OF METAL IONS WITH EDTA LINKED TO OLIGODEOXYRIBONUCLEOTIDES

The chelates of metal ions with EDTA covalently linked to the 5′end of oligodeoxyribonuclotides(ODN),i.e,ODN5′EDTA·M(Ⅱ),are prepared,in which M(Ⅱ) is Fe(Ⅱ),Co(Ⅱ) or Cu(Ⅱ).The optimum pH value for forming these three chelates is calculated.For ODN5′EDTA Fe(Ⅱ) pH value is 5.8 to 8.6,pH 4.6～8.1 for ODN5′EDTA Co(Ⅱ),and pH 3.4～5.7 for ODN5′EDTA Cu(Ⅱ).Under such pH value conditions neither can Mg(Ⅱ) ion,necessary for cleavage reaction,be competitive with Fe(Ⅱ),Co(Ⅱ) or Cu(Ⅱ) to form EDTA chelate,nor can it be precipitated.The cleavage mechanism of ODN5′EDTA Fe(Ⅱ) for DNA duplex is discussed.Modified ODN binds with DNA duplex in the major groove via hydrogen bond to form triple helix.In the presense of oxygen and reducing agent dithiothreitol,hydroxyl radicals species are generated as intermediates by catalysis of metal ions,and then oxidize the ribo ring and cut the doublestranded DNA at the sites close to the EDTA· Fe(Ⅱ).

Investigation of third-order nonlinear optical properties of two azo-nickel chelate compounds

This paper investigates the third-order nonlinear optical properties of two azo-nickel chelate compounds by the optical Kerr gate method at 830 nm wavelength with pulse duration of 120 fs. Both of the two compounds exhibited large third-order optical nonlinearity. The second-order hyperpolarizability,γ, of Compound 1 is of 1.0 × 10^-31 esu. Due to the charge transfer, the γ of Compound 2 with electron donor and acceptor group is 4.9 × 10^-31 esu, which is a four-time enhancement in comparison with Compound i. The absorption spectra show that the electron push-pull effect, which induces intramolecular charge transfer, leads to the increased optical nonlinearity.

Synthesis and Fluorescent Properties of New Binuclear Europiumβ-Diketone Chelates Eu_mY_(1-m)(TTA)_3phen as Red Electroluminescent Materials

A new type of binuclear europlum β-diketone chelates Eum Y1-m(TTA)3 phen (0≤m≤1) and the influence of the proportion of Y on fluorescence intensity of the Eu-complexes were studied. It was found the proportion of Y3+ could affect the fluorescence properties and the film formation seriously. only m≥0.5.Y3+ could increase the luminescent intensity and improve the film formalion. As a resull. three new binuclear europium β-diketone chelales consisted of Eu, Y1-m (TTA)3phen (m=0.9. 0.7 and 0.5) were designed and synthesized. Their structures were elucidated by IR. UV. DSC and Elementary Analysis. Their PL properties were studied. The results showed that the three binuclear europium β-diketone chelates had better PL properties and film formation than Eu(TYA)3phen. They could emit sharply red light, and fluorescenl wavelength of them was all at 613nm (half bandwidth 10nm). They can be used as red organic electroluminescent materials (OELMs) in organic electrolminescent devices (OELDS).