Univalent Metal Ions Research Articles

Metabolomic analysis, extraction, purification and stability of the anthocyanins from colored potatoes

Colored potatoes have many health benefits because they are rich in anthocyanins. However, the constituent and property of anthocyanins in colored potatoes have not been systematically studied yet. Herein, metabolomic analysis was carried out to investigate the chemical composition of anthocyanins in the four different colored potatoes. After that, the extract and purification conditions, and the stability of the anthocyanins were further studied. The results indicated that the four colored potatoes contained abundant of polyphenols, flavonoids, and anthocyanins. Cyanidin, delphinidin, and malvidin were identified as the major anthocyanidins in purple potatoes, whereas red potatoes were mainly consisted of pelargonidin and its derivatives. 84.47 mg C3GE/100 g DW of anthocyanins was obtained at the optimal conditions, which could be effectively purified macroporous resin of D101. Moreover, the anthocyanins were sensitive to pH, temperature, light, redox agents, and divalent or trivalent metal ions, but stable to sugars and univalent metal ions.

Adsorption and removal of metal ions by smectites nanoparticles: Mechanistic aspects, and impacts of charge location and edge structure

Clay minerals are efficient adsorbents for metal ions and have been widely used to control heavy metals, while a number of critical issues remain elusive. In this study, the fully flexible models for smectites (montmorillonite and beidellite) nanoparticles are developed and then subject to molecular dynamics simulations. Edge rather than basal and interlayer surfaces show much higher adsorption efficacy, and therein univalent metal ions always cause excessive adsorption. For montmorillonite, inner-sphere Pb2+ ions emerge and predominate only at edge surfaces, and have higher stability than inner-sphere Na+ ions, manifesting the central role of edge surfaces to remove heavy metals. The peculiar distribution of edge-O atoms causes similar coordination environments for inner- and outer-sphere metal ions, and inner-sphere metal ions are preferred significantly due to bonding with edge-hydroxyls. Metal ions with smaller radii are more favorable to adsorb at edge surfaces, and those with considerable hydration effects (e.g., heavy metals) can be preferred. Edge surfaces of montmorillonite rather than beidellite are more efficient for adsorption, mainly as a result of distinct adsorption behaviors at basal surfaces that show reversed trends. (010) rather than (110) edges are superior for adsorption, which is caused mainly by structural differences. (010) edges are more exposed to adsorbates, and cleavage of smectites nanoparticles along (010) edges enhances removal of heavy metals. Diffusion, mobility and stability of adsorbed metal ions are also discussed, which further understanding of adsorption at edge surfaces. The findings are consistent with experimental observations available and provide new insights to the complicated processes at clay minerals/water interfaces including control of heavy metals.

Self-assembly of activated lipase hybrid nanoflowers with superior activity and enhanced stability

Lipase-inorganic hybrid nanoflowers were prepared using Ca3(PO4)2 as the inorganic component and lipase from Aspergillus oryzae (A. oryzae) as the organic component. The influences of metal ions with different valence, various additives (surfactant), and synthesis conditions on the activity of the lipase hybrid nanoflowers were systematically investigated. Results revealed that the valence state of metal ions played an important role on the shape and activity of lipase hybrid nanoflowers. The synthesized lipase hybrid nanoflowers using bivalence metal ions (Ca2+, Mn2+, and Zn2+) as the inorganic components exhibited relative high activity. However, very low activities were observed in the lipase hybrid nanoflowers using univalent metal ions (Ag+) or trivalent metal ions (Al3+, Fe3+). More importantly, Ca2+ not only induced self-assemble of lipase hybrid nanoflowers, but also activated the enzyme activity by inducing conformational changes in lipase from A. oryzae. As a result, lipase/Ca3(PO4)2 hybrid nanoflowers (hNF-lipase) exhibited the high activity. The hNF-lipase displayed 9, 12, and 61 folds higher activity than lipase/Ag3PO4 hybrid nanoflowers, lipase/AlPO4 hybrid nanoflowers, and lipase/FePO4 nanoflowers, respectively. Compared with free lipase, the hNF-lipase displayed 172 % increase in activities by using 0.15 mM Tween-80 as an activity inducer (activated hNF-lipase). Furthermore, the hNF-lipase and activated hNF-lipase exhibited increased stability against high temperature and denaturant, and had good storage stability and reusability.

Development of a simple, molecular dynamics‐based method to estimate the thickness of electrical double layers

AbstractElectrical double layers (EDL) exist for all interfaces and determination of EDL thicknesses remains a difficult task. In this study, molecular dynamics (MD) simulations are employed aiming to develop a simple method for effective evaluation of EDL thicknesses. The EDL thicknesses at clay minerals/water interfaces are calculated by MD simulations and empirical Debye lengths, considering different electrolyte solutions (NaCl, KCl, CsCl, PbCl2 and CaCl2), electrolyte concentrations (0∼1.28 mol/L) and charge locations (tetrahedral and octahedral substitutions). Both methods predict the comparable EDL thicknesses at very low concentrations and more EDL compressions at higher concentrations, while MD simulations show the significant improvements in three aspects, as more rational declining trends with increase of concentrations (Critical for estimating EDL thicknesses especially in highly concentrated solutions), inclusion of ion‐specific effects (More EDL compression for divalent than univalent metal ions, and distinct EDL thicknesses for different alkali ions) and reflection of strong dependence on charge locations (EDL thicknesses differ for montmorillonite and beidellite and have a milder declining rate for montmorillonite). Insights are also offered regarding the microstructure of EDLs, and results promote the understanding of EDLs that determine all interfacial properties and processes.

Purification and characterization of a secretory lipolytic enzyme, MgLIP2, from Malassezia globosa

Malassezia globosa is a lipid-dependent yeast that is found on the human skin and is associated with various skin disorders, including dandruff and seborrhoeic dermatitis (SD). Despite its important role in skin diseases, the molecular basis for its pathogenicity is poorly understood. The current hypothesis is that dandruff and SD are linked to fatty acid metabolism and secretory lipolytic enzymes, which hydrolyse sebaceous lipids and release irritating free fatty acids. A previous genomic analysis of M. globosa identified a family of 13 homologous genes predicted to encode secreted lipases. We have also reported that M. globosa had significantly higher extracellular lipase activity compared with other species. To identify the major secretory lipases of this yeast during its growth, we successfully purified and characterized an extracellular lipase MgLIP2. Based on MALDI-TOF MS, the peptide mass fingerprint of a tryptically digested protein MgLIP2 corresponded to ORF MGL_4054 of M. globosa. This lipase showed high esterase activity against 4-nitrophenyl palmitate and 1-naphthyl palmitate but not 1-naphthyl acetate. This enzyme had optimal activity at 30 °C and pH 5.0. Furthermore, the activity significantly increased in the presence of Triton X-100 and was partially inhibited by PMSF but was unaffected by univalent and divalent metal ions.

A Novel Cold-Active and Alkali-Stable β-Glucosidase Gene Isolated from the Marine Bacterium Martelella mediterranea

A β-glucosidase gene designated gluc3m was cloned through construction of a genomic library of Martelella mediterranea 2928. The gluc3m consisted of 2,496bp and encoded a peptide of 832 amino acids that shared the greatest amino acid similarity (59%) with a β-glucosidase of family 3 glycoside hydrolase from Agrobacterium radiobacter K84. The optimum reaction temperature and pH of Gluc3M were 45°C and 8.0, respectively. The K (m) and V (max) for p-nitrophenyl-β-D: -glucopyranoside were 0.18mg/ml and 196.08µmol/min/mg enzyme, respectively. Gluc3M was found to be highly alkali stable, retaining 80% of its maximum enzymatic activity after treatment with pH 11.0 buffers for 24h. Furthermore, the activity of Gluc3M improved remarkably in the presence of univalent metal ions, whereas it was inhibited in the presence of divalent ions. Gluc3M also exhibited significant activities toward various substrates including pNPGlu, pNPGal, salicin, and konjac powder. It is important to note that Gluc3M is a cold-active enzyme that showed over 50% of the maximum enzymatic activity at 4°C. SWISS-MODEL revealed that the amino acids near the conserved domain SDW of Gluc3M contributed to the cold-active ability. Based on these characteristics, Gluc3M has the potential for use in additional studies and for industrial applications.

Bonding Stability and Dehydration Constants for Hydrated Metal Ions

The bonding of water molecules with univalent metal ions (M+) has been studied by electrospray ionization mass spectrometry (ESI-MS). Increasing the voltage between the skimmer cones (referred to as the cone voltage) induced the abstraction of water molecules from M+(H2O)n ions, for n equal to 1 or 2. The ions studied belonged to the alkali metals (M = H, Li, Na, K, Rb, and Cs) and to the copper family (M = Cu and Ag). The energies of water binding with the cations studied change in a different manner for alkali metal cations than for the Ag+, Cu+, and H+ ions. A new method has been presented to determine the bonding stability and the dehydration constants for M+(H2O)n clusters.

Resolving independent ion and ion displacement transport mechanisms in ion channels

Univalent metal ion fluxes in gramicidin channels in bilayer membranes produce linear current–voltage plots. Both independent ion models with first-order rate constants or ion–ion displacement models with pseudo-first-order rate constants reproduce the linear current–voltage behavior. To differentiate the mechanisms, the anomalous behavior of the system at low thallous ion mole fractions is studied using a potential ramp protocol. Under these conditions, the current–voltage plots separate into three linear segments with a low conductance segment at lower potentials and parallel outer segments with higher conductance whose voltage axis intercepts are displaced from zero potential. This displaced threshold potential varies with thallous ion mole fraction but has a constant electrochemical potential for all mole fractions. The current–voltage plots and their properties suggest a low conductance mechanism where thallous ion exclusion from the channel obeys Boltzmann statistics in the electrochemical potential. The higher conductance outer segments for electrochemical potentials that exceed the threshold obey a multi-ion displacement.

Studies on Synthesis of a Cycloheptapeptide and Effects of Different Metal Ions on the Cyclization

AbstractA cyclic heptapeptide, c(Gly‐Ile‐Pro‐Tyr‐Ile‐Ala‐Ala), which was isolated and identified from Stellaria yumumensis French (M), was synthesized by solution method for the first time. Protected heptapeptide Z‐Gly‐Ile‐Pro‐Tyr‐Ile‐Ala‐Ala‐OBzl was synthesized with 3‐(diethoxy‐phosphoryloxy)‐l,2,3‐benzotriazin‐4(3H)‐one (DEPBT) as a coupling reagent. After deprotection of benzyl and benzyloxycarbonyl groups, a free linear heptapeptide H‐Gly‐Ile‐Pro‐Tyr‐Ile‐Ala‐Ala‐OH was cyclized in DMF (2 × 10−3 mol/L) in the presence of nine different metal ions, i. e., Li+, Na+, K+, Cs+, Mg2+, Ca2+, Bai2+, Nr2+ and Cr5+ respectively, using DEPBT as a coupling reagent. Univalent metal ion Cs+ enhanced both the cyclization yield and cyclization rate of H‐Gly‐De‐Pro‐Tyr‐Ile‐Ala‐AlaOH, while some bivalent metal ions, such as Mg2+, Ca2+ and Ni2+ decreased the yields of c (Gly‐Ile‐Pro‐Tyr‐De‐Ala‐Ala) drastically. Trivalent metal ion Cr3+ even inhibited the cyclization reaction completely.

ChemInform Abstract: Promotion of Cyclization of Linear Pentapeptides and Heptapeptide by Different Univalent Metal Ions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Promotion of cyclization of linear pentapeptides and heptapeptide by different univalent metal ions.

Univalent metal ions such as Na+, K+ and Cs+ can enhance not only the cyclization yields of some linear pentapeptides and heptapeptide but also their cyclization rates while some bivalent and trivalent metal ions such as Mg2+, Ca2+, Zn2+, Fe2+, Ni2+ and Cr3+ elevate neither the cyclization yields nor the cyclization rates and some of them prevent the cyclization.

Thermal motion of the univalent metal ions in KCr5S8-type chalcogenides, ternary chromium selenides M xCr5Se8 (M = Rb, Cs)

The nonstoichiometric compounds Rb0.75Cr5Se8 and Cs0.76Cr5Se8 crystallise in the monoclinic space group C2/m (Z = 2) being isostructural to KCr5S8 (Rb0.75Cr5Se8: a = 1877.0(8) pm, b = 361.2(2) pm, c = 902.1(9) pm, b = 104.23(6)°, Rf = 0.0399, 826 unique reflections; Cs0.76Cr5Se8: a = 1885.3(9) pm, b = 362.7(2) pm, c = 910.9(3) pm, b = 104.27(4)°, Rf = 0.0524, 1280 unique reflections). The structures are build up by edge and face shared CrSe6 octahedra forming one-dimensional channels parallel to the monoclinic b axis. In these channels, the alkali metal ions are located. Many compounds of the KCr5S8-structure type display significant enlargement of the U11 or the U22 displacement parameters of the univalent metal ions. A model that can explain the enlargement of these parameters is presented. It is based on the relative size of the MI lattice sites including repulsions and M+ ion deficiency phenomena.

Mechanisms of electrode processes on the iron metals

Mechanisms of the electrode processes occurring on the iron metals which are complicated by the generation of a chemisorbed film on the surface are discussed. The film can be either partially reduced or desorbed at elevated temperatures. It can also be removed during the generation of fresh surface. In its absence, the overall reversible electrode reaction includes consecutive elementary steps of the charge transfer from active centers of adsorption and the step where unstable intermediate univalent metal ions undergo disproportionation.

Extraction equilibria of various metal picrates with 19-crown-6 between benzene and water. Effect of the extra methylene group on extraction ability and selectivity

The overall extraction equilibrium constants ( K ex) of picrates of Li +, Na +, K +, Rb +, Cs +, Ag +, Tl +, and Sr 2+with 19-crown-6 (19C6) were determined between benzene and water at 25°C. The K ex values were analyzed into the constituent equilibrium constants, i.e. the extraction constant of picric acid, the distribution constant of the crown ether, the formation constant of the metal ion–crown ether complex in water, and the ion-pair extraction constant of the complex cation with the picrate anion. The effects of an extra methylene group of 19C6 on the extraction ability and selectivity are discussed in detail by comparing the constituent equilibrium constants of 19C6 with those of 18-crown-6 (18C6). The K ex value of 19C6 for each metal ion is lower than that of 18C6, which is mostly attributed to the higher lipophilicity of 19C6. The extraction ability of 19C6 for the univalent metal ions decreases in the order Tl +>K +>Rb +>Ag +>Cs +>Na +⪢Li +, which is the same as that observed for 18C6. The difference in log K ex between the univalent metals is generally smaller for 19C6 than for 18C6. The extraction selectivity of 19C6 is governed by the selectivity in the ion-pair extraction, whereas that of 18C6 depends on both the selectivities in the ion-pair extraction and in the complexation in water.

Complexation of okadaic acid: a preliminary study.

A complexation study was carried out with okadaic acid (OA) and the univalent metal ions Li+, Na+ and K+, and the divalent metal ions Ca2+ and Mg2+. K+ binding was observed identical with a complex obtained from the natural source (OAC). The pharmacological trials demonstrated that this cation has a very important influence on the pharmacological activity of okadaic acid.

Stabilities in water and Gibbs free energies of transfer from water to nonaqueous solvents of alkali metal ion complexes with 1,2-bis[2-(2-methoxyethoxy)ethoxy]benzene (acyclic polyether)

Stability constants of 1:1 complexes, ML+ (M+ and L being a univalent metal ion and a ligand, respectively), of Na+ and K+ with 1,2-bis[2-(2-methoxyethoxy)ethoxy]benzene (AC · B18C6), a linear counterpart of benzo-18-crown-6 (B18C6), were determined in water at 25°C by conductometry. The stability of ML+ is lower for AC · B18C6 than for B18C6 because of the macrocyclic effect, and AC · B18C6 is selective for Na+ in contrast to B18C6. Also determined were Gibbs free energies of transfer (ΔGH2O→S°) from water to nonaqueous solvent S (S=acetonitrile, propylene carbonate and methanol) of AC · B18C6 and B18C6 at 25°C through measurements of the distribution constants between tetradecane and the polar solvent. From these data as well as the literature values of KML in the nonaqueous solvents and of ΔGH2O→S° of M+, the ΔGH2O→S° values of ML+ complexes of the alkali-metal ions with AC · B18C6 and B18C6 were calculated. The ΔGH2O→S° values of M+ are positive but those of ML+ and L are negative in all the systems. This indicates that, although the M+ ions are more soluble in water than in the nonaqueous solvents, when the M+ forms a complex with the lipophilic L, the complex becomes more soluble in the nonaqueous solvent than in water. The lipophilicity of AC · B18C6 is higher than that of B18C6, but the reverse holds for the ML+ complexes. It was concluded that AC · B18C6 shields the M+ ions less effectively in the complexes from the surrounding solvents than B18C6.

放射線事故時におけるセシウム除去としてのプルシアンブルー

Prussian blue, a blue pigment, belongs to the ferric cyanoferrate (II) group. It binds univalent metal ions, and the binding activity depends on their ionic radius. Prussian blue is not absorbed from the gastrointestinal tract in a significant amount. The cesium is entero-enteric cycled through the intestine. Prussian blue inhibits the reabsorption of the cesium. Many studies using experimental animals showed that the oral administration of Prussian blue increases the rate of the fecal excretion of radiocesium which results in shortening its biological half life. The accident in Goiania, Brazil, in 1987 showed that Prussian blue effectively accelerated the removal of radiocesium without toxicity. In the present review, we describe Prussian blue from a biological aspect and discuss its clinical application for the decontamination of cesium in radiation accidents.

Thermodynamic, Spectroscopic, and Structural Studies of Complexation of Phenol- and Pyridine-Armed Macrocyclic Ligands with Univalent Metal Ions

Log K, {Delta}H, and {Delta}S values for interactions of a series of pyridinoazacrown ethers each bearing a phenol arm (2-6) and two macrocycles each bearing a pyridine arm (7, 8) with Na{sup +}, K{sup +}, Tl{sup +}, and Ag{sup +} have been determined in absolute methanol at 25{degrees}C by calorimetric titration. In each case, the complex stability has the sequence Na{sup +} < K {sup +} < Tl{sup +} {much_lt} Ag{sup +}. The phenol-armed macrocycles exhibit selectivity of more than 4 orders of magnitude for Ag{sup +} over Na{sup +}, K{sup +}, and Tl{sup +}. Attachment of a pendant phenol arm having various substituents to parent macrocycle 1 increases the binding abilities of the resulting ligands. Substituents on the para position of the phenol arm have an appreciable effect on cation-binding constants. Good Hammett correlations are found by plotting log K values vs {sigma}{sub p} for interactions of five phenol-armed macrocyclic ligands (2-6) with Na{sup +}, K{sup +}, and Tl{sup +}. The complexation has been characterized by means of {sup 1}H NMR and UV-visible spectroscopic, and X-ray crystallographic methods. The study indicates that the phenol OH group of 2-6 is capable of forming an intramolecular hydrogen bond with the macroringmore » nitrogen atom and that the complexation in absolute methanol generally does not deprotonate these phenols. In the crystal structure of the Na{sup +} -3 complex, the Na{sup +} is coordinated to all seven of the donor atoms of the ligand and two Na{sup +} -3 complexes join together to form a dimer. The dimer contains an intermolecular hydrogen bond formed between the phenol hydrogen atom of one ligand and the phenolate group of a centrosymmetrically related ligand and two {pi}-{pi} stacking interactions between the electron-deficient pyridine ring of one molecule and the electron-rich phenol ring of the other. 36 refs., 5 figs., 6 tabs.« less

Ion-transfer polarographic study of the distribution of alkali and alkaline-earth metal complexes with 3m-crown-m ether derivatives (m = 6, 8) between water and nitrobenzene phases

Stability constants (β 1 NB ) of the 1:1 cationic complexes of Li+ Na+, K+ Ca2+ Sr2+ and Ba2+ with benzo-18-crown-6 (B18C6), Ca2+ and Sr2+ with 18C6 and dibenzo-18C6 and Li+, Na+, Ca2+, Sr2+ and Ba2+ with dibenzo-24-crown-8 in a nitrobenzene (NB) solution saturated with water (w) were determined at 25°C by ion-transfer polarography. From these values, distribution constants (K D,ML) of the 18C6-derivative complex cations between the w- and NB-phases were evaluated using the thermodynamic relation:K D,ML =Kβ 1 NB , whereK (mol dm−3) is an overall equilibrium constant of the processes related to the complexation in the w-phase. The data on the distribution of the 18C6-derivative complex cations between the two phases and the complexation in the NB-phase were examined on the basis of an increase in the number of water molecules hydrated to the species relevant to these processes. The 18C6 derivatives showed higher solubilities in the NB-phase than in the w-phase by complexing with the univalent-metal ions, while, for the divalent-metal ions, the derivatives showed lower solubilities in the NB-phase.

Thermo-oxidative behaviour of water-borne ink binders in the presence of monovalent metal ion

As a part of continuing studies on the change in solubility characteristics of water-borne flexo ink binders, the thermal behaviour of unneutralized and partially or completely neutralized acrylic copolymer and styrene-maleic anhydride copolymer has been examined relative to a water-based ink binder having no carboxylic acid or anhydride group. Films of ink binder and the inks prepared with these binders were aged at 105 °C before or after adding sodium hydroxide. Solubility behaviour as determined by a swelling study revealed that water solubility of acrylic binder decreased significantly after acid group neutralization and ageing. Styrene-maleic anhydride copolymer also showed similar behaviour but the effect on solubility was less significant. Thermogravimetric and FTIR analyses results suggested a crosslinking reaction by acyclic anhydride formation due to alkali catalysed heating of acrylic and maleic binders. By contrast, the presence of univalent metal ion in a sulfopolyester-based flexo ink binder did not show any crosslinking effect and the water solubility of this binder remained practically unchanged.