Single channel properties of lysenin measured in artificial lipid bilayers and their applications to biomolecule detection

Single channel currents of lysenin were measured using artificial lipid bilayers formed on a glass micropipette tip. The single channel conductance for KCl, NaCl, CaCl(2), and Trimethylammonium-Cl were 474 ± 87, 537 ± 66, 210 ± 14, and 274 ± 10 pS, respectively, while the permeability ratio P(Na)/P(Cl) was 5.8. By adding poly(deoxy adenine) or poly(L-lysine) to one side of the bilayer, channel currents were influenced when membrane voltages were applied to pass the charged molecules through the channel pores. Current inhibition process was concentration-dependent with applied DNA. As the current fluctuations of α-hemolysin channels is often cited as the detector in a molecular sensor, these results suggest that by monitoring channel current changes, the lysenin channel has possibilities to detect interactions between it and certain biomolecules by its current fluctuations.     

Interleukin 6 in autoimmune and inflammatory diseases: a personal memoir

In this review, the author discusses the research that led to the identification and characterization of interleukin 6 (IL-6), including his own experience isolating IL-6, and the roles this cytokine has on autoimmune and inflammatory diseases. The cDNAs encoding B-cell stimulatory factor 2 (BSF-2), interferon (IFN)-β2 and a 26-kDa protein were independently cloned in 1986, which in turn led to the identification of each. To resolve the confusing nomenclature, these identical molecules were named IL-6. Characterization of IL-6 revealed a multifunctional cytokine that is involved in not only immune responses but also hematopoiesis, inflammation, and bone metabolism. Moreover, IL-6 makes significant contributions to such autoimmune and inflammatory diseases as rheumatoid arthritis (RA).IL-6 activates both the STAT3 and SHP2/Gab/MAPK signaling pathways via the gp130 signal transducer. F759 mice, which contain a single amino-acid substitution in gp130 (Y759F) and show enhanced STAT3 activation, spontaneously develop a RA-like arthritis as they age. F759 arthritis is dependent on CD4⁺ T cells, IL-6, and IL-17A, and is enhanced by the pX gene product from human T cell leukemia virus 1 (HTLV-1). Arthritis development in these mice requires that the F759 mutation is present in nonhematopoietic cells, but not in immune cells, highlighting the important role of the interaction between nonimmune tissues and the immune system in this disease. Furthermore, this interaction is mediated by the IL-6 amplifier through STAT3 and NF-κB. Ultimately, this model may represent a general etiologic process underlying other autoimmune and inflammatory diseases. More importantly, the understanding of IL-6 has paved the way for new therapeutic approaches for RA and other autoimmune and inflammatory diseases.     

Electrolytic partial fluorination of organic compounds. 83. Anodic fluorination of N-substituted pyrroles and its synthetic applications to gem-difluorinated heterocyclic compounds

Anodic fluorination of N-substituted pyrroles was carried out in MeCN containing supporting fluoride salts such as Et3N-nHF (n = 2-5) and Et4NF-4HF with use of platinum electrodes under constant current conditions. Anodic fluorination of N-methyl- and N-p-tosylpyrroles having an electron-withdrawing cyano group proceeded smoothly to provide the corresponding fluorinated products in moderate to excellent yields, while anodic fluorination of N-methylpyrrole devoid of an electron-withdrawing cyano group did not take place and a polymeric product was formed at the anode surface. In sharp contrast to the cases of N-methylpyrroles, even N-p-tosylpyrrole devoid of an electron-withdrawing cyano group underwent anodic fluorination efficiently. Diels-Alder reaction of 5,5-difluoro-1-methyl-3-pyrrolin-2-one (2e) derived from anodic fluorination of 2-cyano-1-methylpyrrole (2a) with various dienes was carried out to provide the cycloaddition products in excellent yields. Furthermore, Michael reaction of 2e with various nucleophiles was also successfully carried out to provide the Michael addition products in good to excellent yields.     

Ring of C60 polymers formed by electron or hole injection from a scanning tunneling microscope tip

Carrier (electron or hole) injection from a scanning tunneling microscope tip causes various surface modifications on the molecular scale. We report that injection into C60 close-packed layers forms a ring-shaped distribution of C60 polymers. This can be explained on the basis of the radial propagation and energy dissipation of carriers. Subsequent electron or hole injections enlarge the ring, showing that both carriers can induce both polymerization and depolymerization. Furthermore, we demonstrate visualization of carrier scattering by injecting carriers into C60 layers with grain boundaries.     

High-Yield Synthesis of Gold Microplates Using Amphiphilic Block Copolymers: Are Lyotropic Liquid Crystals Required?

Summary : High-yield synthesis of gold microplates is achieved through autoreduction of hydrogen tetrachloroaureate (III) hydrate (HAuCl₄ · 3H₂O) in aqueous solutions of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer (Pluronic L64, EO₁₃PO₃₀EO₁₃) at ambient conditions, in the absence of added energy, reductant, or other surfactants. The formation by the amphiphilic block copolymer of lyotropic liquid crystals (e.g., ordered cylindrical/hexagonal or lamellar phases) is not required for templating the formation of such microplates.     

Tetrahydrides of third-row transition elements: spin-orbit coupling effects on the stability of rhenium tetrahydride

The potential energy surfaces of low-lying states in rhenium tetrahydride (ReH(4)) were explored by using the multiconfiguration self-consistent field (MCSCF) method together with the SBKJC effective core potentials and the associated basis sets augmented by a set of f functions on rhenium atom and by a set of p functions on hydrogen atoms, followed by spin-orbit coupling (SOC) calculations to incorporate nonscalar relativistic effects. The most stable structure of ReH(4) was found to have a D(2d) symmetry and its ground state is (4)A(2). It is found that this is lower in energy than the dissociation limit, ReH(2)+H(2), after dynamic correlation effects are taken into account by using second-order multireference M?ller-Plesset perturbation (MRMP2) calculations. This reasonably agrees with previous results reported by Andrews et al. [J. Phys. Chem. 107, 4081 (2003)]. The present investigation further revealed that the dissociation reaction of ReH(4) cannot occur without electronic transition from the lowest quartet state to the lowest sextet state. This spin-forbidden transition can easily occur because of large SOC effects among low-lying states in such heavy metal-containing compounds. The minimum-energy crossing (MEX) point between the lowest quartet and sextet states is proved to be energetically and geometrically close to the transition state for the dissociation reaction on the potential energy surface of the lowest spin-mixed state. The MEX point (C(2) symmetry) was estimated to be 9184?cm(-1) (26.3 kcal/mol) higher than the (4)A(2) state in D(2d) symmetry at the MRMP2 level of theory. After inclusion of SOC effects, an energy maximum on the lowest spin-mixed state appears near the MEX point and is recognized as the transition state for the dissociation reaction to ReH(2)+H(2). The energy barrier for the dissociation, evaluated to be MEX in the adiabatic picture, was calculated to be 5643?cm(-1) (16.1 kcal/mol) on the lowest spin-mixed state when SOC effects were estimated at the MCSCF level of theory.     

Collective dynamics of hydrated β-lactoglobulin by inelastic x-ray scattering

Inelastic x-ray scattering measurements of hydrated β-lactoglobulin (β-lg) were performed to investigate the collective dynamics of hydration water and hydrated protein on a picosecond time scale. Samples with different hydration levels h [=mass of water (g)/mass of protein (g)] of 0 (dry), 0.5, and 1.0 were measured at ambient temperature. The observed dynamical structure factor S(Q,ω)/S(Q) was analyzed by a model composed of a Lorentzian for the central peak and a damped harmonic oscillator (DHO) for the side peak. The dispersion relation between the excitation energy in the DHO model and the momentum transfer Q was obtained for the hydrated β-lg at both hydration levels, but no DHO excitation was found for the dry β-lg. The high-frequency sound velocity was similar to that previously observed in pure water. The ratio of the high-frequency sound velocity of hydrated β-lg to the adiabatic one of hydrated lysozyme (h=0.41) was estimated as ～1.6 for h=0.5. The value is significantly smaller than that (～2) of pure water that has the tetrahedral network structure. The present finding thus suggests that the tetrahedral network structure of water around the β-lg is partially disrupted by the perturbation from protein surface. These results are consistent with those reported from Brillouin neutron spectroscopy and molecular dynamics simulation studies of hydrated ribonuclease A.     

Trifluoromethylation of various aromatic compounds by CF3I in the presence of Fe(II) compound, H2O2 and dimethylsulfoxide

Trifluoromethylation of aromatic and hetero-aromatic compounds by CF₃I in the presence of Fe(II) compound, H₂O₂ and dimethylsulfoxide was investigated. Various trifluoromethylated benzene derivatives, six-membered nitrogen-containing aromatic compounds and five-membered hetero-aromatic compounds were obtained under mild conditions. General orientation of electrophilic substitution of aromatic compounds was observed similarly as reported in other radical trifluoromethylation previously.     

Photoresponsive properties of poly(N-isopropylacrylamide) hydrogel partly modified with spirobenzopyran

A photoresponsive hydrogel was prepared by radical copolymerization of N-isopropylacrylamide, a vinyl monomer having a spirobenzopyran residue and cross-linker. By the observation of photoresponsive shrinking and the conductance change, it was confirmed that the hydrogel in an acidic condition exhibited drastic and rapid volume shrinkage and proton dissociation when it was irradiated with blue light. Further, to examine its application to the mass transfer control, we prepared a photo- and thermoresponsive gate membrane by introducing this photoresponsive hydrogel to the surface of a porous membrane. As the first demonstration of the photocontrol of membrane permeation for liquid, it was observed that its permeability for 1 mM HCl aqueous solution increased by 2 times in response to the blue light irradiation, and this photoresponse of the permeability was confirmed to be repeatable.     

Solid-state 17O NMR study of the electric-field-gradient and chemical shielding tensors in polycrystalline gamma-glycine

We report the first experimental determination of the carboxylate oxygen electric-field-gradient (EFG) and chemical shielding (CS) tensors in polycrystalline γ-glycine. Analysis of magic-angle spinning (MAS) and stationary ¹⁷O NMR spectra of [¹⁷O]-γ-glycine obtained at 9.4, 14.1, 16.4, and 18.8 T yields the magnitudes of the ¹⁷O EFG and CS tensors and the relative orientations between the two tensors. Extensive quantum chemical calculations at both the restricted Hartree–Fock and density functional levels have been performed to present the absolute tensor orientations in term of the molecular frame. We have demonstrated that ¹⁷O NMR tensor information could be unambiguously derived by the multiple field analyses of stationary ¹⁷O NMR spectra.