Catalytic addition of alkyne C-H, amine N-H, and phosphine P-H bonds to carbodiimides: an efficient route to propiolamidines, guanidines, and phosphaguanidines.

Various metal complexes (e.g., lanthanides, early transition metals, and alkali metals) can serve as catalyst precursors for the catalytic addition of alkyne C-H, amine N-H, and phosphine P-H bonds to carbodiimides, to give a new family of propiolamidines, guanidines, and phosphaguanidines, some of which were difficult to prepare previously.

Hybridization-sensitive on-off DNA probe: application of the exciton coupling effect to effective fluorescence quenching.

The design of dyes that emit fluorescence only when they recognize the target molecule, that is, chemistry for the effective quenching of free dyes, must play a significant role in the development of the next generation of functional fluorescent dyes. On the basis of this concept, we designed a doubly fluorescence-labeled nucleoside. Two thiazole orange dyes were covalently linked to a single nucleotide in a DNA probe.

Generation of cationic indenyl silylamide gadolinium and scandium complexes [(Ind)Ln{N(SiMe3)2}]+[B(C6F5)4]- and their reactivity for 1,3-butadiene polymerization.

Highly efficient cis-polymerization of butadiene was achieved by using new bis(indenyl) silylamide rare earth complexes with the cooperation of both a borate salt and i-Bu3Al; treatment of these complexes with organoboron compounds unexpectedly yielded new cationic mono(indenyl) amido species relevant to polymerization.

Stereoselective synthesis of beta-L-rhamnopyranosides.

Stereoselective construction of 1,2-cis-beta-L-rhamnopyranoside was achieved by our effective methodology using naphthylmethyl (NAP) ether-mediated intramolecular aglycon delivery (IAD). The complete stereoselective synthesis of the bacterial extracellular polysaccharide, alpha-L-Rhap-(1-->3)-beta-L-Rhap-(1-->4)Glcp from Sphaerotilus natans, was successfully accomplished, clearly demonstrating that the NAP-IAD methodology is highly versatile.

Photoluminescent properties and molecular structures of [NaphAu(PPh(3))] and [mu-Naph {Au(PPh(3))}(2)] ClO(4) (Naph = 2-naphthyl).

The complexes [NaphAu(PPh(3))], and [mu-Naph{Au(PPh(3))}(2)]ClO(4), having the Au-C (aromatic) bond have been synthesized and characterized. The unique structure of with two gold atoms bridged by a naphthyl group has been determined by X-ray crystallography. The intramolecular Au-Au separation in is 2.

Femtosecond time-resolved electronic sum-frequency generation spectroscopy: a new method to investigate ultrafast dynamics at liquid interfaces.

We developed a new surface-selective time-resolved nonlinear spectroscopy, femtosecond time-resolved electronic sum-frequency generation (TR-ESFG) spectroscopy, to investigate ultrafast dynamics of molecules at liquid interfaces. Its advantage over conventional time-resolved second harmonic generation spectroscopy is that it can provide spectral information, which is realized by the multiplex detection of the transient electronic sum-frequency signal using a broadband white light continuum and a multichannel detector. We studied the photochemical dynamics of rhodamine 800 (R800) at the air/water interface with the TR-ESFG spectroscopy, and discussed the ultrafast dynamics of the molecule as thoroughly as we do for the bulk molecules with conventional transient absorption spectroscopy.

Time-of-flight analyzer system to detect reflected particles from a solid surface following low-energy particle injection.

We have developed a time-of-flight analyzer to measure energy distributions of reflected particles from solid surfaces bombarded by low-energy (1-2 keV) ions. The analyzer yields energy distributions of neutrals which can be compared with the energy distributions of charged particles measured by a magnetic deflection-type momentum analyzer. We have tested the system to measure the angular dependence of energy and intensity for neutrals reflected from a polycrystalline W target.

Stress imagining of semiconductor surface by tip-enhanced Raman spectroscopy.

Tip-enhanced Raman imaging of strained silicon reveals the property of nanoscale stress imposed on the lattice. Our approach relies on the highly localized excitation provided by a metallized tip. Surface sensitive detections in nanoscale are realized by a reflection-mode configuration combined with 442-nm excitation and a silver-coated silicon nitride tip.

Hidden electronic excited state of enhanced green fluorescent protein.

Precise two-photon absorption spectra of the green fluorescent protein (GFP) and the mutants sapphire-GFP (T203I) and enhanced GFP (S65T/F64L), as well as a model compound for the chromophore, 4'-hydroxybenzylidene-2,3-dimethylimidazolinone (HBDI) were measured by multiplex two-photon absorption spectroscopy. The observed TPA bands of the anionic forms of enhanced GFP and HBDI were significantly shifted to the higher energy compared with the lowest-energy bands in one-photon absorption spectra. This result indicated the existence of a hidden electronic excited state in the vicinity of the lowest excited singlet (S1) state of the anionic form of the GFP chromophore, which is the origin of the blue shift of the two-photon absorption spectra as well as two-photon fluorescence excitation spectra.

Pyranicin, a non-classical annonaceous acetogenin, is a potent inhibitor of DNA polymerase, topoisomerase and human cancer cell growth.

This report describes the inhibitory activities of the natural and non-natural acetogenins [mucocin (compound 1), jimenezin (compound 2), 19-epi jimenezin (compound 3), muconin (compound 4), pyranicin (compound 5), pyragonicin (compound 6), 10-epi pyragonicin (compound 7), and a gamma-lactone (compound 8)], which were synthesized by us, against DNA polymerase (pol), DNA topoisomerase (topo), and human cancer cell growth. Among the compounds tested, compound 5 was revealed to be the strongest inhibitor of the animal pols and human topos tested, and the IC50 values for pols and topos were 2.3-15.

Viscosity dependence of the kinetic parameters of the radical ion pair in homogeneous solution determined by optically detected X- and ku-band electron spin resonance.

We investigated the dynamics of the radical ion pairs formed by photoinduced electron-transfer reaction from zinc tetraphenyl porphyrin to 2-methyl-1,4-naphthoquinone in mixtures of 2-propanol and cyclohexanol. By the irradiation of a resonant X- (9.16 GHz) or Ku-band (17.

Magnetic isotope effect on kinetic parameters and quantum beats of radical pairs in micellar solution studied by optically detected esr using pulsed microwave.

We investigated the quantum beats, the oscillation between singlet and triplet states of radical pairs induced by the microwave field resonant to one of the component radicals. They were observed as the alternation of the yields of the component radicals by a nanosecond time-resolved optical absorption with the X-band (9.15 GHz) resonant microwave pulse.

Nano-aquarium for dynamic observation of living cells fabricated by femtosecond laser direct writing of photostructurable glass.

We demonstrate the fabrication of three-dimensional (3-D) hollow microstructures embedded in photostructurable glass by a nonlinear multiphoton absorption process using a femtosecond (fs) laser. Fs laser direct writing followed by annealing and successive wet etching in dilute hydrofluoric (HF) acid solution resulted in the rapid manufacturing of microchips with 3-D hollow microstructures for the dynamic observation of living microorganisms and cells in fresh water. The embedded microchannel structure enables us to analyze the continuous motion of Euglena gracilis.

Covalently immobilized biosignal molecule materials for tissue engineering.

Immobilization of biosignal molecules including growth factors and cytokines is important for developing biologically active materials which can contribute to tissue engineering as a component. The immobilization has more meanings than only immobilization of the enzyme in a bioreactor or ligand-receptor interactions, because the immobilized biosignal molecules work on cells which have very complex structures and functions. This review discusses recent progress in immobilization of biosignal molecules, including the mechanisms and design concepts.

Development of a new-type riboswitch using an aptazyme and an anti-RBS sequence.

We constructed a new-type riboswitch, which functions in E. coli, using an aptazyme and an anti-RBS sequence. This riboswitch usually suppresses the gene expression with its anti-RBS sequence bound to the RBS of its own mRNA(OFF), while it activates the translation only when a cofactor of the aptazyme is added to release the anti-RBS sequence from itself as a result of cofactor-induced self-cleavage by the aptazyme (ON).

Intermolecular transfer of aminoacylated adenosine towards chemical aminoacylation of tRNA.

We synthesized two oligonucleotides: one is DNA conjugated with adenosine derivative at 5' terminus as a donor, another RNA phosphorothioated at 3' terminus as an acceptor. By hybridization of the two oligonuleotides, the adenosine derivative was transferred from the donor DNA to the acceptor RNA. In this study, O, O'-isopropylidene-protected adenosine derivative and aminoacylated adenosine were successfully transferred from the donor to acceptor RNA.

Photochemical properties of novel fluorescent probes for detection of DNA.

A variety of fluorescence-labeled DNA oligomers have been developed for gene analysis. We have studied on the development of a new functional fluorescent DNA probe for decrease in false positive signals. Thiazole orange derivatives were designed for the fluorescent label of DNA oligomers.

Convenient method for the preparation of carbamates, carbonates, and thiocarbonates.

A convenient, rapid, and efficient method for the preparation of carbamates from amines with 1-alkoxycarbonyl-3-nitro-1,2,4-triazole transfer reagents is reported. Reactions of newly synthesized stable crystalline reagents with alkyl amines were completed in a few minutes without any additional base, and highly pure carbamates were obtained without chromatographic purification. These highly active reagents are also useful for the selective protection of nucleobases and preparation of carbonates and thiocarbonates.

Identification and characterization of an intracellular lectin, calnexin, from Aspergillus oryzae using N-glycan-conjugated beads.

Recently, asparagine-linked oligosaccharides (N-glycans) have been found to play a pivotal role in glycoprotein quality control in the endoplasmic reticulum (ER). In order to screen proteins interacting with N-glycans, we developed affinity chromatography by conjugating synthetic N-glycans on sepharose beads. Using the affinity beads with the dodecasaccharide Glc(1)Man(9)GlcNAc(2), one structure of the N-glycans, a 75-kDa protein, was isolated from the membranous fraction including the ER in Aspergillus oryzae.

pH-dependent fluorescence of uncharged benzothiazole-based dyes binding to DNA.

Uncharged benzothiazole-based dyes were synthesized, and their fluorescence properties were examined. These fluorescent dyes showed an intense fluorescence in aqueous solution in the presence of DNA. In addition, the fluorescence intensities were pH dependent, while those of the positively charged dyes were nearly independent of pH.

An osmium-DNA interstrand complex: application to facile DNA methylation analysis.

Nucleic acids often acquire new functions by forming a variety of complexes with metal ions. Osmium, in an oxidized state, also reacts with C5-methylated pyrimidines. However, control of the sequence specificity of osmium complexation with DNA is still immature, and the value of the resulting complexes is unknown.

Analyses of carbohydrate binding property of lectin-chaperone calreticulin.

Calreticulin (CRT) is a soluble molecular chaperone of the endoplasmic reticulum. It is a lectin that promotes the folding of proteins carrying N-linked glycans. Recent investigations have revealed that glucosylated high-mannose-type glycans are employed as key elements in this process.