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Bacterial replicative DNA polymerases such as Polymerase III (Pol III) share no sequence similarity with other polymerases. The crystal structure, determined at 2.3 A resolution, of a large fragment of Pol III (residues 1-917), reveals a unique chain fold with localized similarity in the catalytic domain to DNA polymerase beta and related nucleotidyltransferases. The structure of Pol III is strikingly different from those of members of the canonical DNA polymerase families, which include eukaryotic replicative polymerases, suggesting that the DNA replication machinery in bacteria arose independently. A structural element near the active site in Pol III that is not present in nucleotidyltransferases but which resembles an element at the active sites of some canonical DNA polymerases suggests that, at a more distant level, all DNA polymerases may share a common ancestor. The structure also suggests a model for interaction of Pol III with the sliding clamp and DNA.

Figure 7. TEM and elemental analyses of S-HMT@CNTs cathode cycled 100 times and then a-c) charged to 2.8 V and d-f) discharged to 1.9 V. g-j) SEM and EDX-elemental analyses of DF-PCW interlayer recovered from S-HMT@CNT cell cycled 100 times at 1C rate between 1.9 and 2.8 V.

Certain solvent additives significantly affect the morphology of the active layer in bulk heterojunction (BHJ) conjugated polymer solar cells and improve the device performance. Previous examinations of the BHJ films have shown that the best additives are characterized by higher boiling points than the host solvent and are poorer solvents for the conjugated host polymer than for the fullerene acceptor; however, little in the way of a mechanistic explanation has been presented, particularly on the dynamics of the transition from solution to the bulk material. This article combines spectroscopic analysis in various solvent mixtures and during solvent evaporation to show that a key feature of the film growth concerns aggregation of polymer chains into more ordered supramolecular structures prior to complete drying. The driving force for aggregation occurs in a medium that (a) is more fluid and allows chains to find optimal registry or conformations and (b) can solvate the fullerenes. We propose that when a single solvent that is good for the two components of the BHJ blend is used, the chains remain solvated up to a point where viscosity inhibits their motion and they are unable to attain similar packing characteristics.

Both the Wnt/β-catenin and Ras pathways are aberrantly activated in most human colorectal cancers (CRCs) and interact cooperatively in tumor promotion. Inhibition of these signaling may therefore be an ideal strategy for treating CRC. We identified KY1220, a compound that destabilizes both β-catenin and Ras, via targeting the Wnt/β-catenin pathway, and synthesized its derivative KYA1797K. KYA1797K bound directly to the regulators of G-protein signaling domain of axin, initiating β-catenin and Ras degradation through enhancement of the β-catenin destruction complex activating GSK3β. KYA1797K effectively suppressed the growth of CRCs harboring APC and KRAS mutations, as shown by various in vitro studies and by in vivo studies using xenograft and transgenic mouse models of tumors induced by APC and KRAS mutations. Destabilization of both β-catenin and Ras via targeting axin is a potential therapeutic strategy for treatment of CRC and other type cancers activated Wnt/β-catenin and Ras pathways.

Four dendritic electro-optic (EO) chromophores were designed, prepared, and evaluated to explore the effects on EO behavior of end-on relative to side-on chromophore attachment geometry as well as differing chromophore-to-dendrimer core tether groups. Composite samples of APC and dendritic chromophores were found to exhibit considerably more thermally stable EO properties as compared to samples of the corresponding isolated chromophore. Side-on type binding geometry was found most thermally stable, requiring larger thermal activation energies to induce dipole randomization. Incorporation of a long, flexible chromophore-core tether group greatly enhanced average EO coefficients of the dendritic systems.