Inhibition of cysteine protease papain by metal ions and polysulfide complexes,especially mercuric ion

Aim Cysteine proteases are closely associated with many human and non-human pathological processes and are potential targets for metal ions especially Hg^2＋ and the related species. In the present work, on the basis of to the general study on the effects of some metal ions on the activity of papain, a well-known representative of cysteine protease family, the inhibitory effects of Hg^2＋ and polysulfide complexes were studied. Results All the metal ions tested （Hg^2＋, Cu^2＋, Ag^＋, Au^3＋, Zn^2＋, Cd^2＋, Fe^3＋, Mn^2＋, Pb^2＋, Yb^3＋） inhibit the activity of papain anda good correlation between the inhibitory potency and softness-and-hardness was observed. Among the metals, Hg^2＋ was shown to be a potent inhibitor of papain with a Kiof 2 × 10^-7 mol·L^-1 among. Excessive amounts of glutathione and cysteine could reactivate the enzyme activity of papain deactivated by Hg^2＋. These evidences supported that Hg^2＋ might bind to the catalytic site of papain. Interestingly, Hg （Ⅱ） polysulfide complexes were for the first time found to inhibit papain with a Ki of 7 × 10^-6 mol·L^-1, whose potency is close to a well known mercury compound, thimerosal （Ki=2.7 × 10^-6）. In addition, Hg （Ⅱ） polysulfide complexes exhibit good permeability （ 1.9 × 10-5 cm· s^-1） to caco-2 monolayer. Conclusion These results suggested that mercury polysulfide complexes might be potential bioactive species in the interaction with cysteine proteases and other- SH-content proteins, providing a new clue to understand the mechanism of the toxicological and pharmacological actions of cinnabar and other insoluble mercury compounds.

Studies on Electrophilic Substitution of Quasi-Aromatic Metal Ion Complexes

The electrophilic substitution reaction occurring to the chelate ring of the complexes could be regarded as an indication of quasi-aromaticity of the ring systems, no catalyst was used and only triethylamine was employed, implying that the aroylating agents with different p-substituents are polarized enough to be effective electrophiles to attack the methine carbon of the electron-rich substrate 1. This property is probably the clue to polarization of the ligand electrons by the nickel( Ⅱ ) ion and to the participation of the nickel( Ⅱ ) in the π-bond systems of the two coordinated conjugated rings. The linearity relationship between vd-d maxima, E1/2OX(1) and σp are obtained, respectively. The electronic environment of central metal ion as well as the aromaticity of the ring system are affected by the electronic properties of the p-substituents. A comparison of the electrochemical results with each other showed .that when the electronegativity of the substituent was higher, the oxidation(Ni2+/Ni3+) becomes more difficult.

Synthesis and Spectroscopic Characterizations on the Complexation of Three Different Metal Ions Ba(Ⅱ),Ni(Ⅱ),and Ce(Ⅲ)with Atenolol Drug Chelate

Three types of metal ions barium(Ⅱ),nickel(Ⅱ)and cerium(Ⅲ)complexity of ATN drug have been prepared and characterized using molar conductance method,FT-IR,electronic,and 1H-NMR analysis measurements.The chemical and physical results for all atenolol complexes are agreement with the speculated structures.For the divalent(Ba&Ni)and trivalent(Ce)metal atenolol a molar ratio 1∶2 was established.Qualitative chemical analysis showed that for the divalent metal complexes,the chloride ions are not involved in the complexes,suggesting that all of these complexes,[Ba(ATN)2]·2 H2O and[Ni(ATN)2(H2O)2]·4 H2O are neutral.However,for the cerium(Ⅲ)complex,[Ce(ATN)2(NO3)]·3 H2O,the nitrate group is existed inside the coordination sphere.ATN make astable metal complexity with barium(Ⅱ),nickel(Ⅱ)and cerium(Ⅲ)ions.Electronic absorption analysis of Atenolol give two fundamental peaks at 225 nm and 274 nm refers to variation in transition electrons of ligand,UV spectral analysis of the three complexity obtained give asymmetric broad band in the range 200~400 nm,the reults are convenient with the suggestion of metal-nitrogen and metal-oxygen bonds.The infrared analysis data proved that ATN act as bidentate ligand through the N atom of the-NH group and O atom of the deprotonated alcoholic OH group.Nickel(Ⅱ)and cerium(Ⅲ)complexity make six-coordinate geometry,whereas the barium(Ⅱ)complex exhibit four-coordinate geometry.Ni(Ⅱ)-ATN complex has an effective magnetic moment equal 3.12 B.M,that is assigned to octahedral structure.The 1H-NMR spectral results of Ba(Ⅱ)-ATN complexity give strong signal at^4.00 ppm due to protons of-CH2 that influenced by low degree due to complexity.These results confirm the position of chelation through the N atom of the-NH group and O atom of the deprotonated alcoholic OH group.

Synthesizes and Characterization Studies of Some Metal Ion Complexes with EOSBE and MOSBE

This work includes synthesis of 2,2＇-（5,5＇-（ethane-1,2-diyl）bis（1,3,4-oxadiazole-5,2diyl））bis（sulfanediyl）dibenzenamine （EOSBE） and 2,2＇-（5,5＇-methylenebis（1,3,4-oxadiazole-5,2-diyl）bis（sulfanediyl））dibenzenamine （MOSBE）. All synthesized ligands were characterized by IR, ^1H-NMR, ^13C-NMR, UV-visible spectroscopies and molar conductivity. A series of complexes with a general formula [M2LCl4]. Where M（Ⅱ） = Co, Ni, Cu and Zn; L = EOSBE and MOSBE were synthesized in basic media using KOH solution. In these complexes both ligands are bidentate ligands coordinated through sulfur and nitrogen. All complexes have been characterized by IR-spectra, UV-visiblc spectra, conductivity and magnetic susceptibility.

Novel Properties of Supramolecular Complexes Formed by Pairing Cationic Porphyrin and Anionic Metal-Oxo Cluster

MTBPyP (meso-tetrakis(4-N-benzylpyridyl)porphyrin, M=H-2, Zn) bearing positive charge has been shown to associate with SiW12O404- in water solution. The spectral evolution and Job's plots analyses reveal that the relatively stable aggregates contain equal numbers of MTBPyP4(+) and SiW12O404-.

Experimental Study on Surface Reactions of Heavy Metal Ions With Quartz—Aqueous Ion Concentration Dependence

Adsorption of divalent metal ions, including Cu\+\{2+\}, Pb\+\{2+\}, Zn\+\{2+\}, Cd\+\{2+\} and Ni\+\{2+\}, on quartz surface was measured as a function of metal ion concentration at 30℃ under conditions of solution pH=6.5 and ion strength I=0.1mol/L. Results of the experimental measurements can be described very well by adsorption isotherm equations of Freudlich. The correlation coefficients (r) of adsorption isotherm lines are >0.96. Moreover, the experimental data were interpreted on the basis of surface complexation model. The experimental results showed that the monodentate coordinated metal ion surface complex species (SOM\++) are predominant over the bidentate coordinated metal ion surface complex species \ formed only by the ions Cu\+\{2+\}, Zn\+\{2+\} and Ni\+\{2+\}. And the relevant apparent surface complexation constants are lgK\-M=2.2-3.3 in order of K\-\{Cd\}≥K\-\{Pb\}>K\-\{Zn\}>K\-\{Ni\}≥K\-\{Cu\}, and lgβ\-M=5.9-6.8 in order of β\-\{Ni\}>β\-\{Zn\}>β\-\{Cu\}. Therefore, the reactive ability of the ions onto mineral surface of quartz follows the order of Cd>Pb>Zn>Ni>Cu under the above mentioned solution conditions. The apparent surface complexation constants, influenced by the surface potential, surface species and hydrolysis of metal ions, depend mainly on the Born solvation coefficient of the metal ions.

PREPARATION OF FUNCTIONAL MATERIALS BY BLENDING COPOLYESTERS WITH PVA AND METAL COMPLEX FORMATION OF POLYMER BLENDS

Copolyesters having secondary and tertiary amine salt groups in the main and side chains are prepared by chemoselective polymerization. These copolyesters are soluble in a 10% aqueous solution of poly(vinyl alcohol) (PVA) at 90 degree C and act as plasticizer in the blend films cast from the solution. Only a glass transition temperature is observed for all these blends indicating the formation of compatible blends from these polyesters with PVA. These blends exhibit manifold characteristics such as ionic conductivity, complex formation with metal ions, absorption of moisture and color changes. The electric conductivity of the copolyesters and blends is in the range of 10** minus **6 Scm** minus **1. The blends with PVA forms complexes with Cu**2** plus and Co**2** plus . The coordination structure with two chelate rings is suggested for these polymer blend/metal complexes. (Author abstract) 10 Refs.

Metal–Oleate Complex?Derived Bimetallic Oxides Nanoparticles Encapsulated in 3D Graphene Networks as Anodes for Efficient Lithium Storage with Pseudocapacitance

In this manuscript, we have demonstrated the delicate design and synthesis of bimetallic oxides nanoparticles derived from metal–oleate complex embedded in 3D graphene networks(MnO/CoMn_2O_4  GN), as an anode material for lithium ion batteries. The novel synthesis of the MnO/CoMn_2O_4  GN consists of thermal decomposition of metal–oleate complex containing cobalt and manganese metals and oleate ligand, forming bimetallic oxides nanoparticles, followed by a selfassembly route with reduced graphene oxides. The MnO/CoMn_2O_4  GN composite, with a unique architecture of bimetallic oxides nanoparticles encapsulated in 3D graphene networks, rationally integrates several benefits including shortening the di usion path of Li^+ ions, improving electrical conductivity and mitigating volume variation during cycling. Studies show that the electrochemical reaction processes of MnO/Co Mn_2O_4  GN electrodes are dominated by the pseudocapacitive behavior, leading to fast Li^+ charge/discharge reactions. As a result, the MnO/CoMn_2O_4  GN manifests high initial specific capacity, stable cycling performance, and excellent rate capability.

High Electrical Conductivity and Conspicuous Phase Transitions in Single Crystals of K-TCNQ

This paper is to report the temperature dependent electrical conductivity of single crystals of radical ion salt (RIS) potassium-TCNQ (K-tetracyanoquino- dimethane) in a wide range of temperatures from 30 to 500 K. This RIS is quasi-one-dimensional in nature. These single crystals of K-TCNQ are grown by different methods like electrochemical, solution growth and diffusion method. Activation energy is determined for the sample in different temperature regions and found different values. More than one semiconductor to metal phase transition is observed in the studied samples during electrical measurements below and above room temperature. All the features observed in the studied samples are analyzed in the framework of their molecular structure as well as under different effects like disorder, impurity, Coulomb interaction, charge density wave (CDW), scattering and 3-D effects etc.

苯甲羟肟酸在浮选中的应用及作用机理研究进展

苯甲羟肟酸(Benzohydroxamic acid,简称BHA)是一种具有良好选择性的氧化矿捕收剂,近年来在浮选中得到了广泛的应用。本文介绍了BHA的物理化学性质,梳理了BHA及其衍生物在矿物浮选中的应用,总结了BHA在矿物表面的吸附机理。结果表明:BHA是一种与金属离子容易形成杂环配合物的螯合剂,在白钨矿、锡石、钛铁矿、稀土矿物等矿物的浮选中已经广泛使用。BHA主要通过与矿物表面金属位点形成O,O五元环配位结构产生稳定吸附,其吸附性能与溶液中组分BHA−的含量息息相关。金属离子活化能显著提高BHA的捕收性能,分为经典金属离子活化和金属离子有机配合物活化两种形式,以BHA金属离子配合物作为捕收剂是金属离子活化的优选方案。基于以上结论,对BHA未来的研究趋势及重点进行了展望。

羟肟酸捕收剂的结构优化及应用研究进展

羟肟酸作为传统的阴离子型螯合捕收剂,被广泛用于氧化矿物、稀土矿物的浮选。近年来,随着浮选药剂分子设计理论的发展和对浮选药剂作用原理的深入研究,越来越多的新型羟肟酸捕收剂被开发并用于矿物浮选。羟肟酸捕收剂由极性基团和非极性基团组成,通过优化这2种基团的结构可强化捕收剂浮选性能。对于极性基团,可以通过引入羟肟基团、含氮基团以及硫醚基团进行优化;对于非极性基团,可以通过选择合适的烃链结构、引入亲电子或送电子基团进行优化。金属基羟肟酸配合物与矿物表面有2种作用模型,分别是预先吸附活化浮选模型、金属离子界面预组装模型。

Stacking interaction in metal complexes with compositions of DNA and heteroaromatic N-bases

The current development in the intramolecular aromatic-ring stacking interactions in the complexes with compositions of DNA and heteroaromatic N-bases has been reviewed to a great extent, especially the significant contributions in several important systems about ternary mixed-ligand complexes, including nucleotide-metal ion-po-lyaromatic amine, amino acid-metal ion-polyaromatic amine, nucleotide-metal ion-pyridine-like aromatic amine, nucleo-tide-metal ion-amino acid, nucleotide-metal ion-nucleic acid base, nucleic acid base-metal ion, and the important factors affecting the intramolecular aromatic-ring stacking interac-tions in the complexes. Based on the study of stacking inter-action in the complexes, the mechanism of interaction be-tween DNA molecules and complexes of heteroaromatic N-bases has been established, which is crucial for the design and synthesis of the complexes acting as molecular devices of DNA.

Ab initio study of the complexes of first-row transition-metal ions with CH, CH_2, and CH_3

The geometries and bonding characteristics of the complexes of the first-row transition-metal ions with CH, CH2 and CH3 were investigated by ab initio molecular orbital theory. MCH+ and MCH2+ are linear and coplanar, respectively. Both of them are with obvious treble or double bond characteristics, but these multiple bonds are mostly 'imperfect' , The calculated bond dissociation energies of C-M+ ,C=M+ and C=M+ are mostly close to the experimental values, and appear in similar periodic trends from Sc to Zn.

基于1,4-双(2-甲基-1H-咪唑-1-基)苯的2例d^(10)金属配合物的合成、结构和性能研究

以溶剂热法合成了2例基于d^(10)金属离子的配合物[Zn(bmib)(HCOO)_(2)]·3H_(2)O(1)和[Cd(bmib)_(0.5)(tdc)(DMF)(H_(2)O)](2)[bmib=1,4-双(2-甲基-1H-咪唑-1-基)苯,H_(2)tdc=2,5-噻吩二羧酸].2例配合物合成条件除金属盐不同外,其余均相同.结构分析揭示,配合物1中H_(2)tdc并未与金属中心配位,Zn^(2+)采取四配位的模式与2个HCOO-和2个bmib配体连接形成一维“Z”字形链.配合物2中Cd^(2+)则采取六配位的模式,由bmib和H_(2)tdc配体共同桥连构成一维梯形链.结果表明金属中心对配合物的结构至关重要.热重分析显示2例配合物热稳定性较好.固体荧光性质表明配合物1和2有蓝色荧光特征,分别在460和470 nm处有最强荧光发射,有用作发光材料的潜在价值.

A method for calculation of ion distribution in reaction system forming hydroxide

A formula was proposed to calculate the distribution of metal ions quantitatively in chemical reaction system forming hydroxide where precipitation and complex are formed together. The effects of some factors on formation of precipitation and complex were investigated, and the corresponding precipitation rates of zinc, iron （III）, aluminum, copper and magnesium were calculated. As a result, it shows that the proposed formula is reliable. By the proposed formula, the existence state of metal ions in hydroxides reaction system with any metal ions can be well described and the effects of some factors on the distribution of metal ions were determined.

SnO_(2)/metal organic complex composite derived from low-temperature activated metal organic complex for advanced lithium storage

Sn-based metal organic complexes with coordination bonds,multi-active sites,and high theoretical capacity have attracted much attention as promising anodes for lithium ion batteries.However,the low electrical conductivity and huge volume changes restricted their electrochemical stability and practical utilization.Herein,Snbased anode with superior electrochemical performance,including a high reversible capacity of 1050.1 mAh·g^(-1)at 2 A·g^(-1)and a stable capacity of 1105.5 mAh·g^(-1)after 500 cycles at 1 A·g^(-1),was fabricated via a low-temperature calcination strategy from Sn metal organic complexes.The low-temperature calcination process regulates Sn-O bond and prevents the agglomeration of SnO_(2),generating highly dispersed SnO_(2) decorated metal organic complexes and providing sufficient active sites for ion storage.Ex situ characterizations expound that the undecomposed Sn-based metal organic complexes could be transformed into SnO_(2) during lithiation and delithiation,which enhances the electrical conductivity and induces a strong pseudo-capacitive behavior,accelerating the electrochemical kinetics;the multiple solid electrolyte interface with inflexible LiF and flexible ROCO_(2)Li buffers the volume variation of the electrode,resulting in its high electrochemical stability.This work provides a simple strategy for preparing excellent Sn-based anodes from metal organic complexes and reveals the lithium storage mechanism of the prepared Snbased anode.

强碱性ASA-IEF对含氰废水中金属氰络离子的吸附作用分析

在当代冶金工业中氰化物的应用十分广泛,但在反应器中大量的金属氰络离子会对溶液的其他有效反应物造成影响,从而降低冶金的效率。因此研究利用聚丙烯纤维为原料制备一种酰基化强碱性离子交换纤维来吸附溶液中的金属氰络离子。实验结果表明吸附纤维的吸附率可达到87.9%,其最佳吸附温度为65~75℃。该材料的制备为冶金行业含氰废水的处理提供了新的思路,从而促进该行业的发展。

基于EMMs特征的酵母厂生产污水DOM与重金属络合作用分析

以新疆某酵母企业污水为例,利用三维荧光光谱技术分析探讨重金属离子对该城市涉污企业污水溶解性有机物三维荧光光谱的影响规律和DOM—重金属的络合作用,得到以下结论:该企业生产污水为高色度、高浓度有机废水,污水处理厂进水中以类蛋白荧光T峰、B峰为主,类腐殖质荧光A峰、C峰存在但不显著。荧光淬灭法研究显示:不同金属离子浓度对DOM组分荧光性质的影响程度不同,不同金属离子对DOM组分荧光的淬灭程度存在差异,并且金属离子浓度的变化也会导致DOM组分荧光峰位置的改变。利用修正型Stern-Volmer模型来定量描述DOM各组分荧光峰与不同金属离子络合作用的强弱,结果表明:各金属离子均与DOM组分发生络合反应,Cu^(2+)与Mn^(2+)对荧光峰的络合程度为T峰>A峰>C峰>B峰,Fe^(2+)对荧光峰的络合程度为T峰>B峰>A峰>C峰。T峰与各金属离子络合能力为Fe^(2+)>Cu^(2+)>Mn^(2+),B峰为Fe^(2+)>Mn^(2+)>Cu^(2+),C峰与A峰与各金属离子络合能力为Cu^(2+)>Mn^(2+)>Fe^(2+)。

Unravelling the effects of complexation of transition metal ions on the hydroxylation of catechol over the whole pH region

Catechol pollutants(CATPs)serving as chelating agents could coordinate with many metal ions to form various CATPs-metal complexes.Little information is available on the effects of complexation of metal ions on CATPs degradation.This work presents a systematical study of·OH-mediated degradation of catechol and catechol-metal complexes over the whole pH range in advanced oxidation processes(AOPs).Results show that the pH-dependent complexation of metal ions(Zn^(2+),Cu^(2+),Ti^(4+)and Fe^(3+))promotes the deprotonation of catechol under neutral and even acidic conditions.The radical adduct formation(RAF)reactions are both thermodynamically and kinetically favorable for all dissociation and complexa-tion species,and-OH/-O-group-containing C positions are more vulnerable to·OH attack.The kinetic results show that the complexation of the four metal ions offers a wide pH range of effectiveness for catechol degradation.At pH 7,the apparent rate constant(k_(app))values for different systems follow the order of catechol+Ti^(4+)≈catechol+Zn^(2+)>catechol+Cu^(2+)>catechol+Fe^(3+)>catechol.The mechanistic and kinetic results would greatly improve our understanding of the degradation of CATPs-metal and other organics-metal complexes in AOPs.The toxicity assessment indicates that the·OH-based AOPs have the ability for decreasing the toxicity and increasing the biodegradability during the processes of catechol degradation.

Sign Response Mechanism of TCA Self-assembled Fluorescence Probe for Cu^2＋ Detection： FRET Evidence by DFT

A new type of self-assembled molecule ON-OFF fluorescence probe for toxic transition metal ions, made up of thiacalix[4]arene, micelle and fluorescence group, has been studied by DFT/TDDFT method combined with experiment spectra. Since the mechanism of the optical quenching signal response of such self-assembled micelle probe has always been a controversial issue of uncertainty, the spatial construction and geometric structures of the functional units of probe in the Cu2＋ ion detecting process were calculated and the mechanism was investigated by the molecular transition orbital pairs method to explore the origination of ON-OFF fluorescence sign response. The results presented that the signal response mechanism of the micelle probe is ascribed to F？rster resonance energy transfer（FRET） which provides new sights different from most of the conclusions by the related research work reported.