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  • Chase Hunt posted an update 3 days ago

    Amorphous ice is commonly used as a noncrystalline matrix for protecting sensitive biological samples in cryogenic electron microscopy (cryo-EM). The amorphization process of water is complex, and at least two amorphous states of different densities are known to exist, high- and low-density amorphous ices (HDA and LDA). These forms are considered to be the counterparts of two distinct liquid states, namely, high- and low-density liquid water. Herein, we investigate the HDA to LDA transition using electron diffraction and cryo-EM. The observed phase transition is induced by the impact of electrons, and we discuss two different mechanisms, namely, local heating and beam-induced motion of water molecules. The temperature increase is estimated by comparison with X-ray scattering experiments on identically prepared samples. Our results suggest that HDA, under the conditions used in our cryo-EM measurements, is locally heated above its glass-transition temperature.Sensor platforms can benefit from the incorporation of polymer brushes since brushes can concentrate the analyte near the sensor surface. Brushes that absorb acetone vapor are of particular interest since acetone is an important marker for biological processes. We present a simple procedure to synthesize acetone-responsive poly(methyl acrylate) brushes. Using spectroscopic ellipsometry, we show that these brushes respond within seconds and swell by more than 30% when exposed to acetone vapor. Moreover, quartz crystal microbalance measurements demonstrate that the brushes can be exploited to increase the acetone detection sensitivity of sensors by more than a factor 6. Surprisingly, we find that the swelling ratio of the brushes in acetone vapor is independent of the grafting density and the degree of polymerization of the polymers in the brush. This is qualitatively different from swelling of the same brushes in liquid environments, where the swelling ratio decreases for increasing grafting densities. Yet, it indicates that the brushes are robust and reproducible candidates for implementation in vapor sensor systems.A condensed film formation of surfactants with a charged head group at the oil/water interface was achieved by mixing surfactants of different geometric shapes to control molecular packing at the interface. The adsorbed films of mixed tetradecyltrimethylammonium bromide (C14TAB)-cholesterol (Chol) and tetradecylphosphocholine (C14PC)-Chol systems at the hexane/water interface were examined by interfacial tension and X-ray reflectivity measurements. The interfacial tension versus Chol concentration curves have break points because of the expanded-condensed phase transition of the adsorbed film. A two dimensional (2D) phase diagram, phase diagram of adsorption, indicated that 11 mixing in the condensed film is energetically favorable because of stronger mutual interaction between different molecules than between the same ones. The electron density profile normal to the interface manifested that the packing of C14TAB (or C14PC) and Chol molecules is like a 2D solid in the condensed state. As C14TAB and C14PC molecules take a corn shape with a large head group (critical packing parameter CPP ≈ 1/3) and Chol takes an inverted corn shape with a bulky sterol ring (CPP > 1), the mixing of corn shape and inverted corn shape molecules produces well-ordered packing to promote solid-like molecular packing at the interface by energy gain because of vdW interaction between hydrophobic chains in addition to attractive ion-dipole interaction between head groups. Furthermore, the heterogeneous feature in the adsorbed film of the C14TAB-Chol system is explained by an interplay between contact energy and dipole interaction, which contribute to line tension at the domain boundary.Macromolecular protease inhibitors and camelid single-domain antibodies achieve their enzymic inhibition functions often through protruded structures that directly interact with catalytic centers of targeted proteases. Inspired by this phenomenon, we constructed synthetic human antibody libraries encoding long CDR-H3s, from which highly selective monoclonal antibodies (mAbs) that inhibit multiple proteases were discovered. To elucidate their molecular mechanisms, we performed in-depth biochemical characterizations on a panel of matrix metalloproteinase (MMP)-14 inhibitory mAbs. Assays included affinity and potency measurements, enzymatic kinetics, a competitive enzyme-linked immunosorbent assay, proteolytic stability, and epitope mapping followed by quantitative analysis of binding energy changes. The results collectively indicated that these mAbs of convex paratopes were competitive inhibitors recognizing the vicinity of the active cleft, with their significant epitopes scattered across the north and south rims of the cleft. Remarkably, identified epitopes were the surface loops that were highly diverse among MMPs and predominately located at the prime side of the proteolytic site, shedding light on the mechanisms of target selectivity and proteolytic resistance. Substrate sequence profiling and paratope mutagenesis further suggested that mAb 3A2 bound to the active-site cleft in a canonical (substrate-like) manner, by direct interactions between 100hNLVATP100m of its CDR-H3 and subsites S1-S5′ of MMP-14. Overall, synthetic mAbs carrying convex paratopes can achieve efficient inhibition and thus hold great therapeutic promise for effectively and safely targeting biomedically important proteases.In this paper, a series of new ruthenium complexes of the general formula [Ru(NS)(dpphpy)(dppb)]PF6 (Ru1-Ru3), where dpphpy = diphenyl-2-pyridylphosphine, NS ligands = 2-thiazoline-2-thiol (tzdt, Ru1), 2-mercaptopyrimidine (pySm, Ru2), and 4,6-diamino-2-mercaptopyrimidine (damp, Ru3), and dppb = 1,4-bis(diphenylphosphino)butane, were synthesized and characterized by elemental analysis, spectroscopic techniques (IR, UV/visible, and 1D and 2D NMR), and X-ray diffraction. WAY-100635 5-HT Receptor antagonist In the characterization, the correlation between the phosphorus atoms and their respective aromatic hydrogen atoms of the compounds in the assignment stands outs, by 1H-31P HMBC experiments. The compounds show anticancer activities against A549 (lung) and MDA-MB-231 (breast) cancer cell lines, higher than the clinical drug cisplatin. All of the complexes are more cytotoxic against the cancer cell lines than against the MRC-5 (lung) and MCF-10A (breast) nontumorigenic human cell lines. For A549 tumor cells, cell cycle analysis upon treatment with Ru2 showed that it inhibits the mitotic phase because arrest was observed in the Sub-G1 phase.

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