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The gene encoding the nucleocapsid protein (N protein) is cloned and the protein is expressed, purified and refolded as shown by (super 1)H NMR measurement. It has been proposed that the low stability of N protein may be critical for the stability and function of SARS virus.

Nanostructured thiospinel-based transition metal sulfides with high-density active sites hold great application potentials as non-noble electrocatalysts. In this paper, high-performance bifunctional oxygen electrocatalysts of well-designed Ni, Cu, Co-based mixed sulfides, which combine two highly active thiospinels of NiCu2S4 and CuCo2S4, have been prepared successfully through solvothermal reaction, calcination, and the following sulfurization. The products of Ni, Cu, Co-based mixed sulfides present unique hollow structures with mesopores, in which several nanoparticles-assembled hollow nanospheres of 30-50 nm in thickness are nested one by one, forming multishell morphologies. Benefiting from the synergistic effect from combined NiCu2S4 and CuCo2S4 and the well-designed hollow structures with large electroactive surfaces/interfaces and efficient mass transportation, the obtained Ni, Cu, Co-based mixed sulfides exhibit remarkable electrocatalytic activities and excellent long-term durability toward not only oxygen reduction reaction (ORR) but also oxygen evolution reaction (OER). Regarding the overall oxygen-based electrocatalytic performance, the mixed sulfides present an extremely low potential difference (0.73 V) between the ORR and OER in KOH electrolyte, delivering significant superiority to their oxide counterparts and the commercial catalyst of Pt/C, as well as most of the oxygen bicatalysts reported recently. Therefore, the obtained Ni, Cu, Co-based mixed sulfides hold great promise as low-cost bifunctional catalysts with high efficiency for oxygen- based advanced energy storage systems. [ABSTRACT FROM AUTHOR]

An alkoxide-catalyzed reduction of benzolactams to isoindoles with silanes was realized. With t-BuOK as the catalyst and Ph2SiH2 as the reductant, a series of benzolactams containing different functional groups were reduced to the corresponding isoindoles, which could be captured by N-phenyl maleimide to form Diels-Alder products in moderate to good yields. Deuterium labeling studies and the hydrosilylation of benzolactam in DMF indicated that the deprotonation of benzolactams took place at C3 potion during the reduction. [ABSTRACT FROM AUTHOR]

An expedient diastereoselective synthesis of highly functionalized indolo[2,3-α]quinolizidines adopting a cisH2/H12b geometry has been realized by a Pictet−Spengler/lactamization cascade sequence. The absolute stereochemistry at C2, C3, and C12b was governed by the originally created chirality of the Michael adduct through organocatalyzed conjugate addition of dialkyl malonates to α,β-unsaturated aldehydes. [ABSTRACT FROM AUTHOR]

Nanoparticles possess unique properties as a result of their large surface area per unit volume and therefore can be functionalized by the immobilization of enzymes for a variety of biosensing applications. Changes in the tertiary conformation of -lactoglobulin adsorbed on 90 nm silica nanoparticles with time were inferred using tryptophan fluorescence and Fourier transform infrared spectroscopy (FTIR) for different surface concentrations, temperature, pH, ionic strength, and 2,2,2-trifluoroethanol (TFE) and dithiothreitol (DTT) concentrations. Rapid initial unfolding followed by a much slower rate at longer times was observed, with the extent of unfolding being higher at lower surface concentrations, higher ionic strengths, higher temperature, higher TFE and DTT concentrations, and pI. The effect of temperature on the unfolding of adsorbed protein on the nanoparticle surface was similar to that in the bulk even though the extent of unfolding was higher for adsorbed protein molecules. The results of the extent of change in tertiary conformation using FTIR as indicated by the change in the ratio of amide II‘/amide I were consistent with those obtained by tryptophan fluorescence whereas the rates of conformational changes given by FTIR were found to be much faster. Circular dichroism (CD) spectra showed that altering the surface concentration by itself did not change the secondary structure of -lactoglobulin on the surface. TFE was found to increase the helix content at the expense of the fraction of the sheet, whereas the sheet was converted to an unordered conformation in the presence of DTT. [ABSTRACT FROM AUTHOR]

Endostatin is a potent angiogenesis inhibitor. The structure of endostatin is unique in that its secondary structure is mainly irregular loops and β-sheets and contains only a small fraction of α-helices with two pairs of disulfide bonds in a nested pattern. We choose human endostatin as a model system to study the folding mechanism of this kind. Nuclear magnetic resonance (NMR), tryptophan emission fluorescence, and circular dichroism (CD) were used to monitor the unfolding process of endostatin upon acid titration. Urea-induced unfolding was used to measure the stability of endostatin under different conditions. Our results show that endostatin is very acid-resistant; some native structure still remains even at pH 2 as evidenced by ¹H NMR. Trifluoroethanol (TFE) destabilizes native endostatin, while it makes endostatin even more acid-resistant in the low pH region. Stability measurement of endostatin suggests that endostatin is still in native structure at pH 3.5 despite the decreased stability. Acid-induced unfolding of endostatin is reversible, although it requires a long time to reach equilibrium below pH 3. Surprisingly, the α-helical content of endostatin is increased when it is unfolded at pH 1.6, and the α-helical content of the polypeptide chain of unfolded endostatin increases linearly with TFE concentration in the range of 0-30%. This observation indicates that the polypeptide chain of unfolded endostatin has an intrinsic α-helical propensity. Our discoveries may provide clues for refolding endostatin more efficiently. The acid-resistance property of endostatin may have biological significance in that it cannot be easily digested by proteases in an acidic environment such as in a lysosome in the cell. [ABSTRACT FROM AUTHOR]