Trypsin immobilization by direct adsorption on metal ion chelated macroporous chitosan-silica gel beads

Silica gel bead coated with macroporous chitosan layer (CTS-SiO₂) was prepared, and the metal immobilized affinity chromatographic (IMAC) adsorbents could be obtained by chelating Cu²⁺, Zn²⁺, Ni²⁺ ions, respectively on CTS-SiO₂, and trypsin could be adsorbed on the IMAC adsorbent through metal–protein interaction forces. Batch adsorption experiments show that adsorption capacity for trypsin on these IMAC adsorbent variated with change of pH. The maximal adsorption reached when the solution was in near neutral pH in all three IMAC adsorbents. Adsorption isothermal curve indicated that maximal adsorption capacity could be found in the Cu²⁺-CTS-SiO₂ with the value of 4980 ± 125 IU g⁻¹ of the adsorbent, while the maximal adsorption capacity for trypsin on Zn²⁺ and Ni²⁺ loaded adsorbent was 3762 ± 68 IU g⁻¹ and 2636 ± 53 IU g⁻¹, respectively. Trypsin immobilized on the IMAC beads could not be desorbed by water, buffer and salt solution if the pH was kept in the range of 5–10, and could be easily desorbed from the IMAC beads by acidic solution and metal chelating species such as EDTA and imidazole. The effect of chelated metal ions species on CTS-SiO₂ beads on the activity and stability of immobilized trypsin was also evaluated and discussed. Trypsin adsorbed on Zn-IMAC beads retained highest amount of activity, about 78% of total activity could be retained. Although the Cu-IMAC showed highest affinity for trypsin, only 25.4% of the calculated activity was found on the beads, while the activity recovery found on Ni-IMAC beads was about 37.1%. A remarkable difference on stability of trypsin immobilized on three kinds of metal ion chelated beads during storage period was also found. Activity of trypsin on Cu-IMAC decreased to 24% of its initial activity after 1-week storage at 4 °C, while about 80% activity was retained on both Ni-IMAC and Zn-IMAC beads. Trypsin immobilized on Zn-CTS-SiO₂ could effectively digest BSA revealed by HPLC peptide mapping.     

Invertase reversibly immobilized onto polyethylenimine-grafted poly(GMA–MMA) beads for sucrose hydrolysis

The epoxy group containing poly(glycidyl methacrylate-co-methylmethacrylate) poly(GMA–MMA) beads were prepared by suspension polymerisation and the beads surface were grafted with polyethylenimine (PEI). The PEI-grafted beads were then used for invertase immobilization via adsorption. The immobilization of enzyme onto the poly(GMA–MMA)–PEI beads from aqueous solutions containing different amounts of invertase at different pH was investigated in a batch system. The maximum invertase immobilization capacity of the poly(GMA–MMA)–PEI beads was about 52 mg/g. It was shown that the relative activity of immobilized invertase was higher then that of the free enzyme over broader pH and temperature ranges. The Michaelis constant (K_m) and the maximum rate of reaction (V_max) were calculated from the Lineweaver–Burk plot. The K_m and V_max values of the immobilized invertase were larger than those of the free enzyme. The immobilized enzyme had a long-storage stability (only 6% activity decrease in 2 months) when the immobilized enzyme preparation was dried and stored at 4 °C while under wet condition 43% activity decrease was observed in the same period. After inactivation of enzyme, the poly(GMA–MMA)–PEI beads can be easily regenerated and reloaded with the enzyme for repeated use.     

Solute adsorption and enzyme immobilization on chitosan beads prepared from shrimp shell wastes

The equilibrium and kinetics of adsorption of reactive dye RR222 and Cu²⁺, and the activity of immobilization of acid phosphatase, on highly swollen chitosan beads were examined at 30°C. The chitosan was prepared from shrimp shell wastes and was cross-linked with different dosages of glutaraldehyde or glyoxal (100–80,000 mg/l). It was shown that the amounts of solute adsorption and the immobilization capacity of acid phosphatase on cross-linked chitosan beads were substantially affected by their degree of cross-linking. The cross-linking rate of chitosan with glutaraldehyde could be described by a pseudo-second-order equation and the cross-linking equilibrium by the Freundlich equation. This provided an experimental method to control the degree of cross-linking of chitosan beads. Finally, the activity and lifetime of the immobilized enzyme were measured to evaluate the application potential.     

Affinity separation of immunoglobulin G subclasses on dye attached poly(hydroxypropyl methacrylate) beads

Poly(hydroxypropyl methacrylate) [poly(HPMA)] gel beads with an average size of 150–200 μm were prepared by suspension polymerization of hydroxypropyl methacrylate (HPMA). The poly(HPMA) gel beads were characterized by swelling studies, surface area measurements, scanning electron microscopy (SEM) and elemental analysis. Poly(HPMA) gel beads had a specific surface area of 88.6 m²/g. The dye Reactive Green HE 4BD was chemically attached to yield dye-poly(HPMA) gel beads at an average concentration of 44.3 μmol dye/g bead with a swelling ratio of 75%. These dye attached gel beads were used in the separation of immunoglobulin-G (IgG) through adsorption–elution studies. The non-specific adsorption of IgG on the poly(HPMA) gel beads was 0.5 mg/g. The attachment of Reactive Green HE 4BD significantly increased the adsorption of IgG up to 71 mg/g. The Langmuir adsorption model was found to be applicable in interpretation of data pertaining to the adsorption studies of IgG with Reactive Green HE 4BD attached to the poly(HPMA) gel beads. The adsorption of IgG was found to be optimal at pH 7.0. The adsorption of IgG was observed to decrease by about 76% as the NaCl concentration was increased from 0.001 to 0.1 M. The IgG adsorption capacity of the dye attached poly(HPMA) gel beads was determined for a commercially available IgG solution to be 4.2 mg/g for IgG₁, 64.5 mg/g for IgG₂, 7.1 mg/g for IgG₃ and 10.8 mg/g for IgG₄. The Reactive Green HE 4BD attached poly(HPMA) gel beads have a significant adsorption capacity for IgG₂. The quantity of adsorbed IgG₂ is three times higher than the quantity of the other subclasses, IgG₁, IgG₃ and IgG₄. A similar adsorption behaviour was observed when the albumin free human plasma was used. The quantity of adsorbed IgG₂ is higher than the quantity of the other subclasses, IgG₁, IgG₃ and IgG₄. Adsorption capacities for albumin free human plasma were obtained as 6.4 mg/g for IgG₁, 67.8 mg/g for IgG₂, 5.2 mg/g for IgG₃ and 8.6 mg/g for IgG₄. Significant amount of the adsorbed IgG (up to 95%) was eluted in 1 h in the elution medium containing 2.0 M NaCl. Repeated adsorption/elution processes showed that these dye attached gel beads are suitable for IgG adsorption.     

Conformational transitions and aggregation in poly(dA)-poly(dT) system induced by Na+ and Mg2+ ions

Effects of Mg²⁺ ions on thermally induced conformational transitions in the synthetic poly(dA)·poly(dT) and poly(dA)·2poly(dT) were studied in the buffered solutions (pH 6.9), containing 0.1 or 1 M NaCl at polynucleotide concentration of 0.1–0.3 mM (in nucleic bases). The experiments consist of measurements of the UV absorption and intensity of conventional visible static light scattering. The diagram of conformational transitions in the poly(dA)–poly(dT)–Mg²⁺ system was constructed on a basis of experimental data obtained. Anomalously strong light scattering, like critical opalescence, has been revealed at 0.1 M NaCl and [Mg²⁺]≥20 mM in the melting range of both polynucleotides, which eventually disappeared after the completion of polymer strands separation. The effect presumably is caused by a fluctuation process of polymer strands complexing which arises at a certain concentration of Mg²⁺ ions.     

Metal ion-coordinating properties of imidazole and derivatives in aqueous solution: interrelation between complex stability and ligand basicity

The stability constants of the 1:1 complexes formed between Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ or Cd²⁺ (M²⁺) and the simple, sterically unhindered imidazole-type ligands, imidazole, 1-methylimidazole, 5-chloro-1-methylimidazole, N-(2,3,5,6-tetrafluorophenyl)imidazole or 4′-(imidazol-1-yl)acetophenone (L), were determined by potentiometric pH titrations in aqueous solution (25°C; I = 0.5 M, NaNO₃). The construction of log K_ML^M versus pK_HL^H plots results in straight lines; the equations for the least-squares lines are calculated and listed. These data allow calculation of the expected stability constant for a complex of any imidazole-type ligand, provided its pK_HL^H value (in the pK_a range 4–8) is known. For the stabilities of Fe²⁺ complexes with imidazole-type ligands an estimation procedure is provided. It is shown further that the complex formation between 1-methylbenzimidazole (MBI) and Mn²⁺, Ni²⁺, Cu²⁺ or Zn²⁺ is s sterically hindered, i.e. the data points for these M(MBI)²⁺ complexes do not fall on the straight lines defined by the imidazole-type ligands.     

Detection of heavy metal toxicity using cardiac cell-based biosensor

Biosensors incorporating mammalian cells have a distinct advantage of responding in a manner which offers insight into the physiological effect of an analyte. To investigate the potential applications of cell-based biosensors on heavy metal toxicity detection, a novel biosensor for monitoring electrophysiological activity was developed by light-addressable potentiometric sensor (LAPS). Extracellular field potentials of spontaneously beating cardiomyocytes could be recorded by LAPS in the range of 20 μV to nearly 40 μV with frequency of 0.5–3 Hz. After exposed to different heavy metal ions (Hg²⁺, Pb²⁺, Cd²⁺, Fe³⁺, Cu²⁺, Zn²⁺; in concentration of 10 μM), cardiomyocytes demonstrated characteristic changes in terms of beating frequency, amplitude and duration under the different toxic effects of ions in less than 15 min. This study suggests that, with the physiological monitoring, it is possible to use the cardiac cell-based biosensor to study acute and eventually chronic toxicities induced by heavy metal ions in a long-term and no-invasive way.     

Mg2+ ion effect on conformational equilibrium of poly A . 2 poly U and poly A poly U in aqueous solutions

Differential UV spectroscopy and thermal denaturation were used to study the Mg²⁺ ion effect on the conformational equilibrium in poly A · 2 poly U (A2U) and poly A · poly U (AU) solutions at low (0.01 M Na⁺) and high (0.1 M Na⁺) ionic strengths. Four complete phase diagrams were obtained for Mg²⁺–polynucleotide complexes in ranges of temperatures 20–96 °C and concentrations (10⁻⁵–10⁻²) M Mg²⁺. Three of them have a ‘critical’ point at which the type of the conformational transition changes. The value of the ‘critical’ concentration ([Mg_t²⁺]_cr=(4.5±1.0)×10⁻⁵ M) is nearly independent of the initial conformation of polynucleotides (AU, A2U) and of Na⁺ contents in the solution. Such a value is observed for Ni²⁺ ions too. The phase diagram of the (A2U+Mg²⁺) complex with 0.01 M Na⁺ has no ‘critical’ point: temperatures of (3→2) and (2→1) transitions increase in the whole Mg²⁺ range. In (AU+Mg²⁺) phase diagram at 0.01 M Na⁺ the temperature interval in which triple helices are formed and destroyed is several times larger than at 0.1 M Na⁺. Using the ligand theory, a qualitative thermodynamic analysis of the phase diagrams was performed.     

Purification and partial characterization of Cu, Zn containing superoxide dismutase from entomogenous fungal species Cordyceps militaris

Cordyceps militaris mycelium produced mainly Cu, Zn containing superoxide dismutase (Cu, Zn-SOD). Cu, Zn-SOD activity was detectable in the culture filtrates, and intracellular Cu, Zn-SOD activity as a proportion protein was highest in early log phase culture. The effects of Cu²⁺, Zn²⁺, Mn²⁺ and Fe²⁺ on enzyme biosynthesis were studied. The Cu, Zn-SOD was isolated and purified to homogeneity from C. militaris mycelium and partially characterized. The purification was performed through four steps: (NH₄)₂SO₄ precipitation, DEAE-sepharose™ fast flow anion-exchange chromatography, CM-650 cation-exchange chromatography, and Sephadex G-100 gel filtration chromatography. The purified enzyme had a molecular weight of 35070 ± 400 Da and consisted of two equal-sized subunits each having a Cu and Zn element. Isoelectric point value of 7.0 was obtained for the purified enzyme. The N-terminal amino acid sequence of the purified enzyme was determined for 12 amino acid residues and the sequences was compared with other Cu, Zn-SODs. The optimum pH of the purified enzyme was obtained to be 8.2–8.8. The purified enzyme remained stable at pH 5.8–9.8, 25 °C and up to 50 °C at pH 7.8 for 1.5 h incubation. The purified enzyme was sensitive to H₂O₂, KCN. 2.5 mM NaN₃, PMSF, Triton X-100, β-mercaptoethanol and DTT showed no significant inhibition effect on the purified enzyme within 5 h incubation period.     

A thermostable alkaline active endo-β-1-4-xylanase from Bacillus halodurans S7: Purification and characterization

A thermostable, alkaline active xylanase was purified to homogeneity from the culture supernatant of an alkaliphilic Bacillus halodurans S7, which was isolated from a soda lake in the Ethiopian Rift Valley. The molecular weight and the pI of this enzyme were estimated to be around 43 kDa and 4.5, respectively. When assayed at 70 °C, it was optimally active at pH 9.0–9.5. The optimum temperature for the activity was 75 °C at pH 9 and 70 °C at pH 10. The enzyme was stable over a broad pH range and showed good thermal stability when incubated at 65 °C in pH 9 buffer. The enzyme activity was strongly inhibited by Mn²⁺. Partial inhibition was also observed in the presence of 5 mM Cu²⁺, Co²⁺ and EDTA. Inhibition by Hg²⁺ and dithiothreitol was insignificant. The enzyme was free from cellulase activity and degraded xylan in an endo-fashion.     

Binding of divalent copper and calcium ions to poly I

The effect ot Cu²⁺ and Ca²⁺ ions, on the ultraviolet differential (UVD) spectra of single-stranded poly I was studied and the coordination (Δε_b) and conformation (Δε_c) conponents of the spectra calculated The comparison of Δε_b and the UVD spectrum of protonated IMP leads to the conclusion that N(7) ot inosine-5'-monophosphate (IMP) is a coordinating site tor Ca²⁺ and Cu²⁺ ions on the polymer bases. The binding ot Ca²⁺ and Cu²⁺ ions causes differently directed displacements of the four absorption bands of poly I, which are observed in the wavenumber range (50-34) × 10³ cm⁻¹ The calculation of concentration dependencies tor the association constants (K“) ot Ca²⁺ and Cu²⁺ ions binding to poly I bases shows that the binding is cooperative The K“ values for the poly I + Ca²⁺ complex are two orders of magnitude lower than those for the poly 1 + Cu²⁺ complex At low ion concentrations, binding to the poly I phosphates predominates and increases the degree of the polynucleotide helicity. At higher concentrations the spectra are mainly affected by the ion binding to bases, which results in melting of the helical parts of poly I At Ca²⁺ concentrations exceeding 10⁻³ M light-scattering aggregates are formed. The degree of monomer order in them is close to that observed in multistranded helices of poly I     

Effect of cesium on the volume of the helix-coil transition of dA.dT polymers and their ligand complexes

The pressure dependence of the helix–coil transition of poly(dA)∙poly(dT) and poly[d(A-T)]·poly[d(A-T)] in aqueous solutions of NaCl and CsCl at concentrations between 10 and 200 mM is reported and used to calculate the accompanying volume change. We also investigated the binding parameters and volume change of ethidium bromide binding with poly(dA)∙poly(dT) and poly[d(A-T)]·poly[d(A-T)] in aqueous solutions of these two salts. The volume change of helix–coil transition of poly(dA)∙poly(dT) in Cs⁺-containing solutions differs by less than 1 cm³ mol^− 1 from the value measured when Na⁺ is the counter-ion. We propose that this insensitivity towards salt type arises if the counter-ions are essentially fully hydrated around DNA and the DNA conformation is not significantly altered by salt types. Circular dichroism spectroscopy showed that the previously observed large volumetric disparity for the helix–coil transition of poly[d(A-T)]·poly[d(A-T)] in solutions containing Na⁺ and Cs⁺ is likely result of a Cs⁺-induced conformation change that is specific for poly[d(A-T)]·poly[d(A-T)]. This cation-specific conformation difference is mostly absent for poly(dA)∙poly(dT) and EB bound poly[d(A-T)]·poly[d(A-T)].     

Production d'NH4 par la crevette Crangon crangon L. dans deux écosystémes côtiers. approche expérimentale et étude de l'influence du sédiment sur le taux d'excrétion

Estimation of the ammonia production of the shrimp C. crangon in two littoral ecosystems (oligotrophic sand and eutrophic mud) was determined in winter and summer conditions from laboratory observations in experimental microcosms. The ammonia excretion rate of C. crangon was not influenced by either the sediment type or the ammonia concentration of the overlying water; on the other hand, the mean excretion rate and the response to initial handling stress increased markedly as shrimp were deprived of soft substratum.

The daily ammonia production of C. crangon was 16 μmol NH₃ · g ⁻¹ wet wt · day ⁻¹ in winter and 40 μmol in summer. A gross production of 12 μmol NH₃ · m⁻² · day ⁻¹ and 300–700 μmol μ m⁻² · day⁻¹, respectively, could be expected in the two ecosystems studied. This would account for 5% (winter) and 2–4% (summer) of the total NH⁺₄ flux at the sediment-water interface. The contribution of the excretion of all macrofauna to the NH⁺₄ flux from the sediment is discussed.     

Purification and characterization of UDPG:ginsenoside Rd glucosyltransferase from suspended cells of Panax notoginseng

Heterogeneity of ginsenosides is an interesting and important issue because those structure-similar secondary metabolites have different or even totally opposite pharmacological activities. In this work, a new enzyme UDP-glucose:ginsenoside Rd glucosyltransferase (UGRdGT), which catalyzes the formation of ginsenoside Rb₁ from ginsenoside Rd [Biotechnol. Bioeng. 89: 444–52, 2005], was purified approximately 145-fold from suspended cells of Panax notoginseng with an overall yield of 0.2%. Purification to apparent homogeneity, as judged by SDS-PAGE, was successfully achieved by using sequential ammonium sulphate precipitation, anion-exchange chromatography and native PAGE. The enzyme had a molecular mass of 36 kDa, and its activity was optimal at pH 8.5 and 35 °C. The enzyme activity was enhanced by Mn²⁺, Ca²⁺ and Mg²⁺, but strongly inhibited by Zn²⁺, Hg²⁺, Co²⁺, Fe²⁺ and Cu²⁺. The apparent K_m value for UDP-glucose and ginsenoside Rd was 0.32 and 0.14 mM, respectively. The biotransformation yield from ginsenoside Rd to Rb₁ by UGRdGT in 50 mM Tris–HCl buffer at pH 8.5 and 35 °C was over 80%. This work provides a basis for further molecular study on the ginsenoside Rb₁ biosynthesis by P. notoginseng cells and it is also useful for potential application to in vitro biotransformation from ginsenoside Rd to Rb₁.     

Copper-Ligand Interactions and Physiological free Radical Processes. Part 2. Influence of Cu2+ Ions on Cu+-Driven Oh Generation and Comparison with Their Effects on Fe2+-Driven Oh Production

In our search to establish a reference ·OH production system with respect to which the reactivity of copper(II) complexes could then be tested, the influence of free Cu²⁺ ions on the Cu⁺/H₂O₂ reaction has been investigated.

This influence depends on the C_Cu²⁺/C_Cu⁺ ratio. At low Cu²⁺ concentrations, ·OH damage to various detector molecules decreases with increasing Cu²⁺ concentrations until C_Cu²⁺/C_Cu⁺ reaches unity. Above this value, ·OH damage increases sharply until C_Cu²⁺/C_Cu⁺ becomes equal to 5 with salicylate and 2 with deoxyribose, ratios for which the protective effect of Cu²⁺ cancels. Finally, at higher concentrations, Cu²⁺ ions logically add their own ·OH production to that normally expected from Cu⁺ ions. The possible origin of this unprecedented alternate effect has been discussed. The possible influence of Cu⁺ ions on the generation of ·OH radicals by water gamma radiolysis has also been tested and, as already established for Cu²⁺ in a previous work, shown to be nonexistent. This definitely confirms that either form of ionised copper cannot scavenge ·OH radicals in the absence of a Iigand.     

The use of chemically modified and unmodified cassava waste for the removal of Cd, Cu and Zn ions from aqueous solution

The use of different chemically modified cassava waste biomass for the enhancement of the adsorption of three metal ions Cd, Cu and Zn from aqueous solution is reported in this paper. Treating with different concentrations of thioglycollic acid modified the cassava waste biomass.

The sorption rates of the three metals were 0.2303 min⁻¹ (Cd²⁺), 0.0051 min⁻¹ (Cu²⁺), 0.0040 min⁻¹ (Zn²⁺) and 0.109 min⁻¹ (Cd²⁺), 0.0069 min⁻¹ (Cu²⁺), 0.0367 min⁻¹ (Zn²⁺) for 0.5 and 1.00 M chemically modified levels, respectively. The adsorption rates were quite rapid and within 20–30 min of mixing, about 60–80% of these ions were removed from the solutions by the biomass and that chemically modifying the binding groups in the biomass enhanced its adsorption capacity towards the three metals. The results further showed that increased concentration of modifying reagent led to increased incorporation, or availability of more binding groups, in the biomass matrix, resulting in improved adsorptivity of the cassava waste biomass. The binding capacity study showed that the cassava waste, which is a serious environmental nuisance, due to foul odour released during decomposition, has the ability to adsorb trace metals from solutions.     

Purification and characterization of xylanase from Aspergillus ficuum AF-98

The purification and characterization of xylanase from Aspergillus ficuum AF-98 were investigated in this work. The extracellular xylanase from this fungal was purified 32.6-fold to homogeneity throughout the precipitation with 50–80% (NH₄)₂SO₄, DEAE-Sephadex A-50 ion exchange chromatography and Sephadex G-100 chromatography. The purified xylanase (specific activity at 288.7 U/ mg protein) was a monomeric protein with a molecular mass of 35.0 kDa as determined by SDS-PAGE. The optimal temperature and pH for the action of the enzyme were at 45 °C and 5.0, respectively. The xylanase was activated by Cu²⁺ up to 115.8% of activity, and was strongly inhibited by Hg²⁺, Pb²⁺ up to 52.8% and 89%, respectively. The xylanase exhibited K_m and V_max values of 3.267 mg/mL, 18.38 M/min/mg for beechwood xylan and 3.747 mg/mL, 11.1 M/min/mg for birchwood xylan, respectively.     

Immobilization of catalase into chemically crosslinked chitosan beads

Bovine liver catalase was immobilized into chitosan beads prepared in crosslinking solution. Various characteristics of immobilized catalase such as the pH–activity curve, the temperature–activity curve, thermal stability, operational stability, and storage stability were evaluated. Among them the pH optimum and temperature optimum of free and immobilized catalase were found to be pH 7.0 and 35 °C. The K_m value of immobilized catalase (77.5 mM) was higher than that of free enzyme (35 mM). Immobilization decreased in V_max value from 32,000 to 122 μmol (min mg protein)⁻¹. It was observed that operational, thermal and storage stabilities of the enzyme were increased with immobilization.     

Thermostability of β-xylosidase from Aspergillus sydowii MG49

Heating of Aspergillus β-xylosidase at 85°C ± 1°C and pH 5.5–6.0 (optimum for activity), causes irreversible, covalent thermoinactivation of the enzyme, involving oxidation of the thiol groups that are required for catalysis. Exogenous addition of cysteine, DTT, GSH and mercaptoethanol stabilizes the enzyme by extending its half-life. A similar effect is also exhibited by bivalent cations like Mg²⁺, Mn²⁺, Co²⁺, Ca²⁺and Zn²⁺ while, on the other hand Cu²⁺ accelerates thermoinactivation. Chemical modification of crude β-xylosidase with cross-linking agents like glutaraldehyde or covalent immobilization to a nonspecific protein like gelatin and BSA also enhances enzyme thermostability. These results suggest that addition of thiols and bivalent metal ions to a crude β-xylosidase preparation or immobilization/chemical modification enhances its thermal stability, thus preventing loss of catalytic activity at elevated temperatures.     

Manganese(II) complexes of an acyclic phenol-based dinucleating ligand with four methoxyethyl chelating arms: synthesis, structure, magnetism and electrochemistry

Dinuclear manganese(II) complexes [Mn₂(bomp)(PhCO₂)₂]BPh₄ (1), [Mn₂(bomp)(MeCO₂)₂]BPh₄ (2), and [Mn₂(bomp)(PhCO₂)₂]PF₆ (3) were synthesized with a dinucleating ligand 2,6-bis[bis(2-methoxyethyl)aminomethyl]-4-methylphenol [H(bomp)]. Dinuclear zinc complex [Zn₂(bomp)(PhCO₂)₂]PF₆ (4) was also synthesized for the purpose of comparison. X-ray analysis revealed that the complex 1·CHCl₃ contains two manganese ions bridged by the phenolic oxygen and two benzoate groups, forming a μ-phenoxo-bis(μ-benzoato)dimanganese(II) core. Magnetic susceptibility measurements of 1–3 over the temperature range 1.8–300 K indicated antiferromagnetic interaction (J=−4 to −6 cm⁻¹). Cyclic voltammograms of 3 showed a quasi-reversible oxidation process at +0.9 V versus a saturated sodium chloride calomel reference electrode, assigned to Mn^IIMn^II/Mn^IIMn^III.