Highly specific affinities of short peptides against synthetic polymers

We investigated polymer-binding 7-mer peptides that recognize differences in the polymer stereoregularity of all-purpose poly(methyl methacrylate)s (PMMAs) with simple chemical structures. Quantitative surface plasmon resonance measurements detected association/dissociation processes of the peptides against PMMA film surfaces, followed by an estimation of kinetic parameters such as association/dissociation rate constants and affinity constants. Greater association and smaller dissociation constants of the peptides were observed against a target isotactic PMMA than the structurally similar reference syndiotactic PMMA, followed by greater affinity constants against the target. A c02 peptide composed of the Glu-Leu-Trp-Arg-Pro-Thr-Arg sequence showed the greatest affinity constant (2.8x10(5) M(-1)) for the target, which was 41-fold greater than that for the reference, thus demonstrating extremely high peptide specificities. The substitution of each amino acid of the c02 peptide to Ala (Ala scanning) clearly revealed the essential amino acids for the affinity constants; the essential order was Pro5>Thr6>Arg7>Glu1>Arg4. In fact, the shorter 4-mer peptide composed of the C-terminal Arg-Pro-Thr-Arg sequence of the c02 peptide still demonstrated strong target specificity, although the N-terminal 4-mer peptide Glu-Leu-Trp-Arg completely lost its specificity. The possible conformations modeled with Molecular Mechanics supported the significance of the Arg-Pro-Thr-Arg sequence. The thermodynamic parameters of the c02 peptide suggested an induced fit mechanism for the specific affinity. The present affinity analyses of polymer-recognizing peptides revealed significant and general information that was essential for potential applications in peptidyl nanomaterials.     

The Japanese perspective on TIMSS

The International Association for the Evaluation of Educational Achievement (IEA) undertook three international mathematics studies: the first, FIMS, in 1976, the second, SIMS, in 1980, and the third, TIMSS, in 1995, 13-year-old Japanese students were included in these studies. The purpose of this paper is to discuss the level of mathematics achievement and attitudes toward mathematics among Japanese students and the situation of mathematics education in Japan, based on the results of TIMSS and previous studies. From our analysis of results, we can indicate the following points: although achievement in the fundamental techniques of calculation can be viewed in general as satisfactory, the attainment levels cannot be regarded as acceptable for problems which require a high degree of thinking and comprehension. And from the consequence of international comparison about interest and attitude, it became evident that a smaller fraction of Japanese students have a favorable opinion than in other countries.     

Near-field optical imaging using force detection with new tip-electrode geometry

We propose a new tip-electrode geometry to detect an (optical) evanescent field using noncontact atomic force microscopy. Using a semi-transparent metal electrode on the prism surface, the force sensitivity due to evanescent field in new tip-electrode geometry was enhanced by a factor of about 1000, comparing with that in old tip-electrode geometry where electrode was located behind the prism. Furthermore, this tip-electrode geometry avoids the electrostatic field caused by the residual charges and contact-electrified charges near the prism surface, which affects the force sensitivity due to evanescent field. We demonstrated the high resolution imaging of the evanescent field on the Au film with 15-nm (λ/33) lateral resolution.     

Quadruple Decker [3.3][3.3][3.3]Orthocyclophane Acetal—An Orthocyclophane Ladder

Through clever bridging of orthocyclophanes (in this case by acetalization), molecules such as 1 can be formed with four benzene rings in a stacked face-to-face arrangement. UV/Vis spectroscopic and electrochemical properties of 1 are governed by π–π through-space interactions within the molecule.     

Directional Solidification of Faceting Material in a Centrifuge

In situ observation of directional solidification of salol was carried out at a centrifuge acceleration of 10 G (G = 9.81 m/s²). Growth rate, temperature distribution and flow pattern in front of the solid-liquid interface could be simultaneously measured and visualized using a microscopic interferometer and thermocouples. The specimens were transparent, faceting organic compounds, which develop cellular arrays. These materials of commercial grade were purified by several zone-refining cycles on a laboratory scale and were enclosed in quartz glass cells. The solidification were controlled by the imposed temperature gradient in the cell and cooling rate at the both side of the cell. The growth direction was adjusted to opposite to the acceleration vector. We found appearance of a local recalescence region in front of the growing surface not only under 1 G but 10 G. The uniformity of the recalescence region along the interface seemed to be defined by the flow induced by the centrifuge acceleration. We considered the non-uniform temperature distribution ahead of the interface as one of the driving forces of the interface breakdown.     

ProSeg: a database of local structures of protein segments

Integration of knowledge on the sequence-structure correlation of proteins provides a basis for the structural design of artificial novel proteins. As one of strategies, it is effective to consider a short segment, whose size is in between an amino acid and a domain, as a correlation unit for exploring the structure-to-sequence relationship. Here we report the development of a database called ProSeg, which consists of two sub-databases, Segment DB and Cluster DB. Segment DB contains tens of thousands of segments that were prepared by dividing the primary sequences of 370 proteins using a sliding L-residue window (L = 5, 9, 11, 15). These segments were classified into several thousands of clusters according to their three-dimensional structural resemblance. Cluster DB contains much cluster-related information, which includes image, rank, frequency, secondary structure assignment, sequence profile, etc. Users can search for a suitable cluster by inputting an appropriate parameter (i.e., PDB ID, dihedral angles, or DSSP symbols), which identifies the backbone structure of a query segment. Analogous to a language, ProSeg could be regarded as a ‘structure-sequence dictionary’ that contains over 10,000 ‘protein words’. ProSeg is freely accessible through the Internet ().     

Dielectric and tunable properties of highly (110)-oriented (Ba<Subscript>0.65</Subscript>Sr<Subscript>0.35</Subscript>)TiO<Subscript>3</Subscript> thin films deposited on Pt/LaNiO<Subscript>3</Subscript>/SiO<Subscript>2</Subscript>/Si substrates

Highly (110)-oriented Ba_0.65Sr_0.35TiO₃ films were deposited on Pt/LaNiO₃/SiO₂/Si substrates by a sol–gel method. It was found that the (110)-preferred Pt film was very effective for growing (110)-oriented ferroelectric films with perovskite structure. The as-grown Ba_0.65Sr_0.35TiO₃ films showed good dielectric properties with dielectric constant and loss tangent tan δ = 0.026. Excellent dielectric tunability was also achieved in the (110)-oriented films. With applying an electric field of 230 kV/cm at 100 kHz, the dielectric tunability and the figure of merit can reach up to 63.4% and 16, respectively. These results indicate that the highly (110)-oriented Ba_0.65Sr_0.35TiO₃ film is a promising candidate for the applications in microwave tunable devices.     

Self‐Assembled Nanogel of Hydrophobized Dendritic Dextrin for Protein Delivery

Highly branched cyclic dextrin derivatives (CH‐CDex) that are partly substituted with cholesterol groups have been synthesized. The CH‐CDex forms monodisperse and stable nanogels with a hydrodynamic radii of ≈10 nm by the self‐assembly of 4–6 CH‐CDex macromolecules in water. The CH‐CDex nanogels spontaneously trap 10–16 molecules of fluorescein isothiocyanate‐labeled insulin (FITC‐Ins). The complex shows high colloidal stability: no dissociation of trapped insulin is observed after at least 1 month in phosphate buffer (0.1 M , pH 8.0). In the presence of bovine serum albumin (BSA, 50 mg · mL^?1), which is a model blood system, the FITC‐Ins trapped in the nanogels is continuously released (≈20% at 12 h) without burst release. The high‐density nanogel structure derived from the highly branched CDex significantly affects the stability of the nanogel–protein complex.

     

Chemiluminescence assay for quinones based on generation of reactive oxygen species through the redox cycle of quinone

A sensitive and selective chemiluminescence assay for the determination of quinones was developed. The method was based on generation of reactive oxygen species through the redox reaction between quinone and dithiothreitol as reductant, and then the generated reactive oxygen was detected by luminol chemiluminescence. The chemiluminescence was intense, long-lived, and proportional to quinone concentration. It is concluded that superoxide anion was involved in the proposed chemiluminescence reaction because the chemiluminescence intensity was decreased only in the presence of superoxide dismutase. Among the tested quinones, the chemiluminescence was observed from 9,10-phenanthrenequinone, 1,2-naphthoquinone, and 1,4-naphthoquinone, whereas it was not observed from 9,10-anthraquinone and 1,4-benzoquinone. The chemiluminescence property was greatly different according to the structure of quinones. The chemiluminescence was also observed for biologically important quinones such as ubiquinone. Therefore, a simple and rapid assay for ubiquinone in pharmaceutical preparation was developed based on the proposed chemiluminescence reaction. The detection limit (blank + 3SD) of ubiquinone was 0.05 μM (9 ng/assay) with an analysis time of 30 s per sample. The developed assay allowed the direct determination of ubiquinone in pharmaceutical preparation without any purification procedure. Figure Chemiluminescence generated through the redox cycle of quinone