ATP as building blocks for the self-assembly of excitonic nanowires

Supramolecular nanowires are specifically self-assembled from adenosine 5'-triphosphate (ATP) and dichloro-substituted thiacarbocyanine dyes. Spectral blue-shift and induced circular dichroism with exciton coupling are observed upon mixing the dye and ATP molecules in water. These observations indicate the formation of chiral 1/ATP supramolecular assemblies with excitation energy delocalized in the parallel-oriented (H-aggregated) chromophores. Interestingly, formation of H-aggregates is facilitated most in the presence of ATP and not by other nucleotides (ADP or AMP). In electron microscopy, aqueous 1/ATP mixture gives developed nanowires with a minimum width of ca. 10 nm and lengths of several micrometers. The ATP-directed nanowires exhibit reversible thermal self-assembly accompanied by supramolecular thermochromism. This is the first example of ATP-based supramolecular nanoassemblies, and the use of small biomolecules as building blocks for functional supermolecules provides a new perspective in the design of bio-nanomaterials.     

Study of carbon nanotubes-HRP modified electrode and its application for novel on-line biosensors

In this paper, multi-walled carbon nanotubes (MWCNTs) were successfully immobilized on the surface of a glassy carbon electrode by mixing with horse-radish peroxidase (HRP). The electrochemical behavior of H2O2 was also studied with the MWCNTs-HRP modified electrode as a working electrode. The MWCNTs-HRP modified electrode showed excellent response of reduction current for the determination of H2O2 at the potential of -300 mV (vs. Ag/AgCl). We assembled the MWCNTs-HRP modified electrode in a thin-layer flow cell and the H2O2 solution was continuously introduced into the cell with a syringe pump. We optimized the sensitivity of the H2O2 sensor by adjusting the working potential and the pH of the buffer solution. The peak current increased linearly with the concentration of H2O2 in the range 3.0 x 10(-7) to approximately 2.0 x 10(-4) mol L(-1). The detection limit is 1.0 x 10(-7) mol L(-1) (S/N = 3). The interferences from ascorbic acid, uric acid and other electroactive substances can be greatly excluded since the sensor can be operated at -300 mV. Stability and reproducibility of the MWCNTs-HRP chemically modified electrode were also studied in this paper. Fabricated with glucose and lactate oxidase, the MWCNTs-HRP electrode was also applied to prepare the on-line glucose and lactate biosensors because of the high sensitivity for the determination of H2O2.     

Characterization of Ce@C82 and its anion

Ce@C(82) is isolated by high-performance liquid chromatography (HPLC) and the cage symmetry is determined as C(2)(v)() by measuring the (13)C NMR spectra of its anion. The (13)C NMR peaks of [Ce@C(82)](-) show temperature-dependent shifts ascribed to the f electron remaining on the Ce atom. Both Ce@C(82) and [Ce@C(82)](-) are silent in electron spin resonance spectroscopy (ESR) because of the highly anisotropic g matrix as well as of the fast relaxation process originating from the orbital angular momentum of the f electron. This is the complementary relationship to the observation of the paramagnetic shift in (13)C NMR. [Ce@C(82)](-) has lower stability in air than [La@C(82)](-).     

Total chemical synthesis of large CCK isoforms using a thioester segment condensation approach

Silver-ion mediated thioester segment condensation was applied to the chemical synthesis of high molecular weight isoforms of cholecystokinin (CCK). Three building blocks, a C-terminal Tyr(SO₃H)-containing segment and two partially protected thioester segments having a C-terminal Pro residue, were prepared using Fmoc-based chemistry and 2-chlorotrityl chloride (Clt) resin as a solid support. The entire peptide chain was successfully synthesized by two consecutive silver-ion mediated condensation reactions using these building blocks. A brief TFA treatment of the final condensation product gave highly homogeneous CCK-58 in a satisfactory yield. This peptide exhibited glucose-dependent insulinotropic activity at levels comparable to CCK-33. These results demonstrate the usefulness of the silver-ion mediated segment condensation approach in the preparation of large sulfated peptides.     

Copolymerization of styrene with maleic anhydride initiated by thiol compounds

Copolymerization of styrene (ST) with maleic anhydride (MAH) initiated by thiol compound was investigated under various conditions. The kinetics of copolymerization of ST with MAH initiated by p-toluenethiol (pTT) was studied in dioxane in the temperature range of 25–60°C, and the rates (R_p) of copolymerization and activation energy were determined. R_p was found to depend on [pTT],^0.6 ([ST] + [MAH])^2.7. The overall energy of activation was 10.8 kcal/mol in the temperature range of 25–60°C. A mechanism involving the formation of a complex between MAH and pTT the decomposition of which yields the initial radical is suggested.     

Total synthesis of (+)-pederin. 1. Stereocontrolled synthesis of (+)-benzoylpedamide

(+)-Benzoylpedamide (5), a right half of (+)-pederin (1), was synthesized stereoselectively based on the newly developed method for the synthesis of 1,3-$\text{syn}$-and 1,3-$\text{anti}$-polyols.     

Preparation and properties of electron donor acceptor complexes of the compounds having capto-dative substituents

In order to examine the “capto-dative” substitution-effect on the electrical conductivity, five compounds which have capto-dative substituents were prepared. Electron withdrawing (capto) group was nitro- or cyano-substituted phenyl and electron donating (dative) one was 5-methyl-5,10-dihydrophenazinyl moiety. The character of intramolecular electron donor acceptor complex of the five compounds were demonstrated by their uv spectra. Electron donor acceptor complexes of them with tetracyanoquinodimethane were prepared and their electrical resistivities were measured.     

SUNBURN CELL: FACTORS INVOLVED IN ITS FORMATION.

Abstract— The sunburn cell (SC) is a type of individual cell death appearing in epidermis principally after exposure to middle-wavelength UV radiation (UVR). Because SC_s can easily be recognized by histologic characteristics, they may provide a countable index of assessment of the degree of UVR injuries. However, despite extensive investigations, the mode of formation of this UVR-induced apoptosis has not fully been understood. In this review article, we are summarizing the results of recent studies with special reference to both the formation mechanisms and their implications in the field of photobiology.     

Application of Fmoc-amino acid carrying an unmasked carbohydrate to the synthesis of the epidermal growth factor-like domain of bovine blood coagulation factor IX

The epidermal growth factor (EGF)-like domain of the bovine blood coagulation factor IX (45-87) carrying glucose at Ser(53) was synthesized by a solid-phase method using 9-fluorenylmethoxycarbonyl (Fmoc)-amino acids. The introduction of Ser(53) was carried out using the benzotriazolyl ester of Fmoc-serine carrying an unmasked glucose. The remaining sequence was also introduced using the benzotriazolyl ester. HPLC analysis of the crude peptide shows that acylation of the free hydroxyl group of the glucose was not significant, demonstrating that the amino acid carrying an unmasked carbohydrate is a useful building block for solid-phase synthesis.     

Reversible and regioselective reaction of La@C82 with cyclopentadiene

The reversible and regioselective reaction of La@C82 with cyclopentadiene was carried out. The activation and thermodynamic parameter of the retro-reaction was estimated from the Arrhenius plots of the rate constants.