Solution structure of S-DNA formed by covalent base pairing involving a disulfide bond

Here, we present the solution structure of a DNA duplex containing a disulfide base pair (S-DNA). The unnatural nucleoside "S" possessing a thiophenyl group as base was incorporated into a self-complementary singled-stranded oligonucleotide. Crosslinking of the disulfide base pair was analyzed by non-denaturing polyacrylamide gel electrophoresis. Under oxidizing conditions a high molecular weight band as 18 mer, corresponding to the double-stranded molecule (5'-GCGASTCGC: 3'-CGCTSAGCG), was found, whereas single-stranded self-complementary 9 mer oligonucleotide GCGASTCGC was detected in the presence of a reducing agent. These results suggest that the oligonucleotide is covalently linked by disulfide bonding under oxidizing conditions, which can be reversibly reduced to two thiol groups under reducing conditions. CD spectrum of S-DNA (CGASTCG) under oxidizing conditions suggested that the duplex had a right-handed double-stranded structure similar to that of natural DNA (B-form, CGATCG). NMR studies confirmed that this CGASTCG resembled natural B-DNA and that the two phenyl rings derived from the disulfide base pairing intercalated into the duplex. However, these two phenyl rings were not positioned in the same plane as the other base pairs. Specifically, NOEs suggest that although CGASTCG adopts a structure similar to B-type DNA, the S-DNA duplex is bent at the point of disulfide base pairing to face the major groove.     

Rapid fabrication of reconstructible hydrogels by electrophoretic microbead adhesion

Hydrogel constructs were rapidly fabricated via the electrophoretic adhesion of oppositely charged microbeads. The reversible preparation of hydrogel constructs was achieved by the reconstruction of microbead networks.     

Titanium complexes supported by an [OSSO]-type bis(phenolato) ligand based on a trans-cyclooctanediyl platform: synthesis, structures, and 1-hexene polymerization

trans-Cyclooctanediyl-bridged [OSSO]-type ligand 4 reacts with TiCl(4)(thf)(2) in toluene to produce the corresponding titanium(IV) dichloro complexes as an inseparable mixture of cis-α isomer 6a and cis-β isomer 6b in a ratio of 2:1, whereas treatment of dilithio salt of 4 with TiCl(3)(thf)(3) in Et(2)O afforded chloride-bridged dimeric titanium(III) complex 8, which indicated the antiferromagnetic character in a nonpolar solvent solution. Di(isopropoxy) titanium(IV) complex 10 having a C(2)-symmetric cis-α configuration was synthesized by the reaction of 4 with Ti(O(i)Pr)(4) in toluene as yellow crystals. Moreover, the reaction of 4 with Ti(NEt(2))(4) in toluene resulted in the unexpected formation of [OSSO]-type bis(phenolato)-bridged dinuclear diamido titanium(IV) complex 11, which adopted a distorted tetrahedral geometry on the titanium center. These titanium complexes were characterized on the basis of their NMR spectroscopic data, and the molecular structures of complexes 8, 10, and 11 were established by single crystal X-ray diffraction. The titanium(IV) and (III) complexes 6 and 8 upon activation with a cocatalyst in toluene polymerized 1-hexene isospecifically to produce poly(1-hexene) having high molecular weight (M(w) = 22,000-52,000 g mol(-1)) and relatively narrow polydispersity (M(w)/M(n) = 1.7-1.8), albeit with low activity [0.27-1.0 g mmol(cat)(-1) h(-1)].     

Blockade of inflammatory responses by a small-molecule inhibitor of the Rac activator DOCK2

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Highlights? CPYPP binds to DOCK2 DHR-2 domain and inhibits its catalytic activity ? CPYPP inhibits DOCK2-mediated Rac activation in cells ? The structural features of CPYPP required for its inhibitory effect were revealed ? CPYPP inhibits lymphocyte migration and activation in vitro and in vivo     

Mineral composition of frozen taro for determination of geographic origin

The mineral composition of frozen food of taro [Colocasia esculenta (L.) Schott] was analyzed to categorize the geographical production place of taro. The concentrations of Co and H₂PO₄ ⁻ were found to be useful to separate the producing place between Japan and China. The analysis was performed by instrumental neutron activation analysis (INAA) and ion chromatography (IC). In the case of INAA, the samples were dried and sealed in a vinyl bag and irradiated with thermal neutrons from JRR3M, installed at Japan Atomic Energy Agency (JAEA). The activated samples were cooled down for a few weeks and the elements (Co, Cr, Fe, Rb, Zn) were determined. Cobalt concentration of frozen taro from China was higher than that from Japan. The tendency was the same in the fresh sample of taro. When concentration of H₂PO₄ ⁻ of frozen sample was measured, taro from Japanese product was higher than that of Chinese one, contrary to fresh sample. This result might be caused by the leakage of H₂PO₄ ⁻ during freezing process, indicating that we should be careful to apply the discrimination indicators. In addition to Co, there was a significant difference of Rb and Fe concentrations between frozen taro from Japan and China.     

Photoluminescence properties of selectively grown InN microcrystals

We investigated the photoluminescence (PL) properties of regularly arranged N‐polar InN microcrystals with m ‐plane sidewall facets. We observed narrow PL emission at 0.678 eV with a linewidth of ～14 meV at 4 K and a clear band‐filling effect with increasing excitation power. We also observed a normal red shift of the PL peak energy as large as 51 meV (～150 nm) with increasing temperature from 4 to 300 K, similar to that observed for non‐degenerated semiconductors. The integrated PL intensity ratio I_300K/I_4K was measured to be 6.1%. These results indicate that InN microcrystals have a low residual carrier density and excellent optical properties without being adversely affected by surface electron accumulation, despite their relatively high surface area. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Heat and mass transfer characteristics of organic sorbent coated on heat transfer surface of a heat exchanger

This paper describes heat and mass transfer characteristics of organic sorbent coated on heat transfer surface of a fin-tube heat exchanger. The experiments in which the moist air was passed into the heat exchanger coated with sorption material were conducted under various conditions of air flow rate (0.5–1.0 m/s) and the temperature of brine (14–20°C) that was the heat transfer fluid to cool the air flow in the dehumidifying process. It is found that the sorption rate of vapor is affected by the air flow rate and the brine temperature. Meanwhile, the attempt of clarifying the sorption mechanism is also conducted. Finally the average mass transfer coefficient of the organic sorbent coated on heat transfer surface of a fin-tube heat exchanger is non-dimensionalzed as a function of Reynolds number and non-dimensional temperature, and it is found that the effect of non-dimensional temperature on them is larger than Reynolds number .     

A report on the 31st Symposium on Heteroatom Chemistry of the Chemical Society of Japan

The 31st domestic Chemical Society of Japan Symposium on Heteroatom Chemistry was held in Wakayama during the period of December 8–10, 2004, under the management of Waro Nakanishi and Satoko Hayashi of Wakayama University. About 250 chemists from various academic institutes and industries enjoyed five plenary lectures, 40 oral presentations, and 72 poster presentations. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:535–547, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20134     

Solving backward stochastic differential equations with quadratic-growth drivers by connecting the short-term expansions

This article proposes a new approximation scheme for quadratic-growth BSDEs in a Markovian setting by connecting a series of semi-analytic asymptotic expansions applied to short-time intervals. Although there remains a condition which needs to be checked a posteriori, one can avoid altogether time-consuming Monte Carlo simulation and other numerical integrations for estimating conditional expectations at each space–time node. Numerical examples of quadratic-growth as well as Lipschitz BSDEs suggest that the scheme works well even for large quadratic coefficients, and a fortiori for large Lipschitz constants.     

On a dendrite generated by a zero-dimensional weak self-similar set

Let S be a zero-dimensional, perfect, compact weak self-similar set generated in dendrite X by a family {f_j} of weak contractions from X to itself. Decomposition space D_f of S due to a continuous mapping f from S onto X is also a dendrite. In the dendrite D_f, there exists a zero-dimensional, perfect, compact weak self-similar set S¹ based on a family each of which is topologically conjugate to f_j. Decomposition space D_f¹ of S¹ due to a continuous mapping f¹ from S¹ onto D_f is again a dendrite. In this manner, through the successive formation of weak self-similar set, we can obtain a sequence X,D_f,D_f¹,… of dendrite any pair in which are mutually homeomorphic.