Screening of Peptide Ligands for Pyrroloquinoline Quinone Glucose Dehydrogenase Using Antagonistic Template-Based Biopanning

We have developed a novel method, antagonistic template-based biopanning, for screening peptide ligands specifically recognizing local tertiary protein structures. We chose water-soluble pyrroloquinoline quinone (PQQ) glucose dehydrogenase (GDH-B) as a model enzyme for this screening. Two GDH-B mutants were constructed as antagonistic templates; these have some point mutations to induce disruption of local tertiary structures within the loop regions that are located at near glucose-binding pocket. Using phage display, we selected 12-mer peptides that specifically bound to wild-type GDH-B but not to the antagonistic templates. Consequently, a peptide ligand showing inhibitory activity against GDH-B was obtained. These results demonstrate that the antagonistic template-based biopanning is useful for screening peptide ligands recognizing the specific local tertiary structure of proteins.     

Possible role of dentin matrix in region-specific deposition of cellular and acellular extrinsic fibre cementum

The mechanism whereby a region-specific deposition of the two types of cementum (cellular cementum and acellular extrinsic fibre cementum) is regulated on the growing root surface was tested using bisphosphonate-affected teeth of young rats and guinea pigs. The animals were injected subcutaneously with 8 or 10 mg P x kg body weight(-1) x day(-1) of 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) for 1 or 2 weeks. In rat molars, HEBP prevented mineralization of newly formed root dentin matrix and totally inhibited de novo deposition of acellular extrinsic fibre cementum. Instead, thick cellular cementum was induced on the non-mineralized root dentin surface, irrespective of the position of the root. In both animals, cellular cementum was also induced on the non-mineralized surface of root analogue dentin in HEBP-affected incisors, where only acellular extrinsic fibre cementum is deposited under normal conditions. In normal rat molars, dentin sialoprotein (DSP) was concentrated along the dentin-cellular cementum border, but not that of dentin and acellular extrinsic fibre cementum. In HEBP-affected rat incisors, DSP was shown to penetrate through the non-mineralized dentin into the surrounding tissues, but not through the mineralized portions. These data suggest that, at the site of cellular cementum formation, putative inducing factors for cellular cementum might diffuse into the periodontal space through the newly deposited mantle dentin matrix before it is mineralized. At earlier stages of root formation, mantle dentin might mineralize more promptly not to allow such diffusion. The timing of mineralization of mantle dentin matrix might be the key determinant of the types of the cementum deposited on the growing root surface.     

Physiology of Cerebellar Reserve: Redundancy and Plasticity of a Modular Machine

The cerebellum is endowed with the capacity for compensation and restoration after pathological injury, a property known as cerebellar reserve. Such capacity is attributed to two unique morphological and physiological features of the cerebellum. First, mossy fibers that convey peripheral and central information run mediolaterally over a wide area of the cerebellum, resulting in the innervation of multiple microzones, commonly known as cerebellar functional units. Thus, a single microzone receives redundant information that can be used in pathological conditions. Secondly, the circuitry is characterized by a co-operative interplay among various forms of synaptic plasticity. Recent progress in understanding the mechanisms of redundant information and synaptic plasticity has allowed outlining therapeutic strategies potentiating these neural substrates to enhance the cerebellar reserve, taking advantage of the unique physiological properties of the cerebellum which appears as a modular and potentially reconfiguring brain structure.     

Investigation of ion adsorption properties of sulfobetaine gel and relationship with its swelling behavior

The adsorption of cations and anions in nitrate solutions on N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate (DMAAPS) gels prepared using various cross-linker and monomer concentrations was investigated. The influence of the temperature and nitrate concentration on the adsorption properties of the gel was evaluated, demonstrating simultaneous adsorption of cations and anions. The amount of Zn²⁺ adsorbed on the gel in Zn(NO₃)₂ solution increased as the cross-linker and monomer concentrations used in the gel preparation increased. For the gel prepared using a higher cross-linker or monomer concentration, elevation of the temperature did not induce any significant change in the amount of Zn²⁺ adsorbed on the gel. Furthermore, for the gel prepared using a lower cross-linker or monomer concentration, the amount of Zn²⁺ adsorbed on the gel decreased significantly as the temperature increased. In addition, an interesting correlation between the degree of swelling of the gel and the amount of Zn²⁺ adsorbed on the gel was found. As the degree of swelling decreased, the adsorption amount increased to eventually achieve a constant value.     

Improvement of SNAr Reaction Rate by an Electron‐Withdrawing Group in the Crosslinking of DNA Cytosine‐5 Methyltransferase by a Covalent Oligodeoxyribonucleotide Inhibitor

DNA cytosine 5‐methyltransferase (DNMT) catalyzes methylation at the C5 position of the cytosine residues in the CpG sequence. Aberrant DNA methylation patterns are found in cancer cells. Therefore, inhibition of human DNMT is an effective strategy for treating various cancers. The inhibitors of DNMT have an electron‐deficient nucleobase because this group facilitates attack by the catalytic Cys residue in DNMTs. Recently, we reported the synthesis and properties of mechanism‐based modified nucleosides, 2‐amino‐4‐halopyridine‐C‐nucleosides (d^XP), as inhibitors of DNMT. To develop a more efficient inhibitor of DNMT for oligonucleotide therapeutics, oligodeoxyribonucleotides (ODNs) containing other nucleoside analogues, which react more quickly with DNMT, are needed. Herein, we describe the design, synthesis, and evaluation of the properties of 2‐amino‐3‐cyano‐4‐halopyridine‐C‐nucleosides (d^XP^CN) and ODNs containing d^XP^CN, as more reactive inhibitors of DNMTs. Nucleophilic aromatic substitution (S_NAr) of the designed nucleosides, d^XP^CN, was faster than that of d^XP, and the ODN containing d^XP^CN effectively formed a complex with DNMTs. This study suggests that the incorporation of an electron‐withdrawing group would be an effective method to increase reactivity toward the nucleophile of the DNMTs, while maintaining high specificity.     

Microstructure of high battery-performance Li2FeSiO4/C composite powder synthesized by combining different carbon sources in spray-freezing/freeze-drying process

Spray-freezing/freeze-drying technique was applied to the synthesis of Li₂FeSiO₄/C composite powders using solutions containing various carbon sources, water-soluble and colloidal carbon, followed by heat treatment. The effects of the carbon sources on the microstructure and battery performance of the synthesized composite powders were investigated. The microstructures of the composite powders were clearly different when different carbon sources were used, ascribed from the thermal behavior of the carbon sources during the heat treatment. It was possible to control the microstructures of Li₂FeSiO₄/C composite powders by combining different carbon sources, and the synthesized composite powders exhibited high discharge capacities by mixing with only a binder for cathode. The composite powders using glucose and Ketjenblack dispersion as carbon sources delivered 165 mAh/g at first discharge capacity at 0.1?C. The developed chain structure suitable for conducting paths in the electrodes and a higher-specific BET surface area, attributed from Ketjenblack, were likely responsible for the higher performance.     

Preparation and Characterization of Pt/Al-ZSM-5 Catalysts and their Reactivities for the Oxidation of CO with N2O at Low Temperatures

Al-ZSM-5 was prepared by treating H-ZSM-5 with an aqueous solution of Al(NO₃)₃ and used as a support for Pt catalysts. The Pt-loaded Al-ZSM-5 acts as an efficient catalyst for CO oxidation with N₂O at 273 K. TEM investigations revealed that Pt clusters with an average particle size of around 1–1.5 nm were homogeneously dispersed within Al-ZSM-5. Moreover, FT-IR and XPS analyses indicated that the small Al₂O₃ clusters formed within Al-ZSM-5 plays a significant role in the formation of highly dispersed Pt clusters within the pore structure of the ZSM-5 zeolite, leading to the high catalytic activity of Pt/Al-ZSM-5 as compared to Pt/ZSM-5.     

All solid-state polymer electrolytes prepared from a hyper-branched graft polymer using atom transfer radical polymerization

We propose an all solid-state (liquid free) polymer electrolyte (SPE) prepared from a hyper-branched graft copolymer. The graft copolymer consisting of a poly(methyl methacrylate) main chain and poly(ethylene glycol) methyl ether methacrylate side chains was synthesized by atom transfer radical polymerization changing the average chain distance between side chains, side chain length and branched chain length of the proposed structure of the graft copolymer. The ionic conductivity of the SPEs increases with increasing the side chain length, branched chain length and/or average distance between the side chains. The ionic conductivity of the SPE prepared from POEM₉ whose POEM content = 51 wt% shows 2 × 10⁻⁵ S/cm at 30 °C. The tensile strength of the SPEs decreases with increases the side chain length, branched chain length and/or average distance between the side chains. These results indicate that a SPE prepared from the hyper-branched graft copolymer has potential to be applied to an all-solid polymer electrolyte.     

A two-layered approach to communicative artifacts

A key issue in social intelligence design is the realization of artifacts that can fluently communicate with people. Thus, we proposed a two-layered approach to enhance a robot’s capacity of involvement and engagement. The upper layer flexibly controls social interaction by dynamic Bayesian networks (DBN) representing social interaction patterns. The lower layer improves the robustness of the system by detecting rhythmic and repetitive gestures. We designed a listener robot that can follow and record humans’ explanation on how to assemble and/or disassemble a bicycle. The implementation of this system is described by assembling the key algorithms presented in this paper.