Isolation of selenoprotein-P and determination of Se concentration incorporated in proteins in human and mouse plasma by tandem heparin affinity and size-exclusion column HPLC-ICPMS

Sel-P is considered to be the most important selenoprotein for evaluating the selenium (Se) status in the body. To isolate and determine Sel-P in plasma, we have developed an analytical method combining heparin affinity (AF) and size-exclusion column (SEC) high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS). We used this method to validate the adsorption efficiency of selenoproteins on a heparin AF column, and to then determine the Se concentrations incorporated in proteins in human and mouse plasma. The adsorption efficiency of Sel-P on a heparin column was more than 90% for both human and mouse plasma. Tandem AF and SEC separation proved to be useful for determining the Se concentrations incorporated in Sel-P in mouse plasma, but not in human plasma, because of nonspecific adsorption of plasma-extracellular glutathione peroxidase (eGPx) and albumin on the heparin AF column. Ultimately, we used the tandem AF and SEC separation method for mouse plasma and SEC separation alone for human plasma. The Se concentration incorporated in selenoproteins determined by our method showed good agreements with the total Se concentration determined following acid digestion.     

Recognition of exterior protein surfaces using artificial ligands based on calixarenes, crown ethers, and tetraphenylporphyrins

Artificial ligands for recognition of exterior protein surfaces can be used for protein detection, protein modification/modulation, and protein separation. This article reviews recent developments of artificial ligands for complexation with exterior protein surfaces, with a focus on studies using calixarene-, crown ether-, and tetraphenylporphyrin-based ligands. Synthetic ligands that recognize amino acid residues can form n:1 supramolecules with proteins. 18-Crown-6 and calix[6]arene derivatives have been used for complexation with the lysine residues of proteins. By comparison, larger ligands that have a central core and multivalent functionalities at the periphery can form 1:1 supramolecules with proteins.     

Cysteine Reactivity Distinguishes Redox Sensing by the Heat-Inducible and Constitutive Forms of Heat Shock Protein 70

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Highlights? The stress-inducible chaperone Hsp72, but not constitutive Hsc70, is prone to oxidation ? Specific cysteine residues in Hsp72 may be important in redox sensing ? Oxidation of Hsp72 causes degradation of its substrate, tau, in cells     

Liquid membrane transport of cytochrome c using a calix[6]arene carboxylic acid derivative as a carrier

The present study examined the liquid membrane transport of the cationic protein cytochrome c, using the macrocyclic compound calix[6]arene, which is a carboxylic acid derivative, as a carrier. The transport rate was governed by carrier concentration and the pH gradient between the feed and the receiving phases, as well as the salt concentration in the aqueous phases. Transport of cytochrome c was examined using a series of calix[n]arene carboxylic acid derivatives (n = 4, 6 and 8). Cytochrome c successfully permeated membranes in the presence of the calix[6]arene derivative. Liquid membrane separation of cytochrome c from a mixture of cationic proteins was demonstrated under optimal conditions. Cytochrome c was selectively extracted by the calix[6]arene carboxylic acid derivative and 77% of the extracted cytochrome c was recovered into the receiving phase. In this liquid membrane system, which discriminates between the number of lysine residues on the surface of proteins, cationic proteins with similar molecular weights and pIs were separated with macrocyclic compounds.     

Formation of solid solution and its effect on lithium insertion schemes for advanced lithium-ion batteries: X-ray absorption spectroscopy and X-ray diffraction of LiCoO2, LiCo1/2Ni1/2O2 and LiNiO2

The X-ray absorption spectra (XAS) of LiCoO₂, LiCo_1/2Ni_1/2O₂ and LiNiO₂ were examined together with X-ray diffraction (XRD). Co and Ni K-edge XANES spectra of LiCo_1/2Ni_1/2O₂ are quite similar to that of LiCoO₂ or LiNiO₂, suggesting that electronic states of Co and Ni in LiCo_1/2Ni_1/2O₂ are Co³⁺ and Ni³⁺. Analytical results of Co and Ni K-edge EXAFS oscillations on the first coordination shell of nickel and cobalt ions in LiCo_1/2Ni_1/2O₂ indicate that the local environment around the targeted species is the same as that in LiCoO₂ or LiNiO₂. Since there is no doubt about the crystal and electronic structures of LiCoO₂ and LiNiO₂, the results indicate that LiCo_1/2Ni_1/2O₂ consists of low-spin states of Co³⁺ and Ni³⁺ distributed at equivalent positions in triangular lattice of sites forming homogeneous transition metal oxide layers. Thus, XAS complements XRD in describing solid solution LiCo_1/2Ni_1/2O₂ of LiCoO₂ and LiNiO₂. The electrochemical behaviors of LiCoO₂, LiCo_1/2Ni_1/2O₂ and LiNiO₂ are also restated and the effects of the formation of solid solution on the change in lattice dimension during topotactic electrochemical reactions are discussed.     

Spray Pyrolysis Preparation of Apatite-Composite Particles for Biological Application

Apatite derived by sol-gel routes through an amorphous state or derived biomimetically is likely to provide chemically and biologically active surfaces. Thus apatite or apatite-composite particles were prepared by spray-pyrolysis of several solutions as they were applicable to medical treatment. Calcium lactate and ammonium dihydrogen phosphate aqueous solutions stabilized with ethylenediaminetetraacetic acid were sprayed ultrasonically and pyrolysed at 600°C to yield amorphous particles of apatite while apatite-ferric oxide composite powders were prepared from the solutions of calcium lactate and ferric nitrate. Solutions of calcium nitrate and titanium ethoxide in 0.5 N HNO₃ were also spray-pyrolysed at 600°C to prepare calcium titanate and titanium oxide particles trapped on a Ti substrate. Apatite could biomimetically be developed on the calcium titanate particles when they were soaked in an acellular simulated body fluid.     

Emission efficiency for particulate forms of iron and aluminum in rain-water measured by inductively-coupled plasma atomic emission spectrometry

The bulk emission efficiency for particulate forms of iron and aluminum in rain-water was evaluated. The efficiencies for iron and aluminum were >80% for particles 0.4–1 μm in diameter and about 17% for particles >8 μm; relative standard deviations were <20%. A procedure is described by which the concentrations of particulate forms of iron and aluminum in rain-water are determined. Fluctuation of particles in rain-water during a rainfall event can be monitored in detail.     

Preparation of porous biodegradable microspheres with direct melting dispersion method

Porous biodegradable microspheres can be prepared by using the direct melting dispersion method without any noxious organic solvents, in which the biodegradable polymer is directly melted and stirred to form the liquid–liquid dispersion followed by cooling in the continuous phase, such as ethylene glycol with the higher melting temperature than polymer. In the experiment, polyhydroxybutyrate (PHB) was adopted as the biodegradable polymer. As particulate porogen, magnetite powder was pre‐mixed into the melted polymer and removed by hydrochloric acid aqueous solution after preparation of the microspheres to make them porous. It was found that the inner surface area was significantly increased by removing magnetite powder. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of tubular titanate via a self-assembly and self-removal process

Novel morphology titanate tubes were successfully synthesized via a self-assembly and self-removal process. After the product was treated by calcinating and washing, crystalline TiO2 tubes were obtained. In this study, two new concepts are applied to design the synthetic route: (i) titanium glycolate rods obtained from an ethylene glycol-mediated process and titanate sheets synthesized using the hydrothermal process were used as the template and the precursor, respectively, and ii) the template was directly removed in the reaction without posttreatment. Furthermore, a possible mechanism was proposed for the formation of tubular structures.