Skinnerstiles1329

Understanding protein corona formation in an aqueous environment at the molecular and atomistic levels is critical to applications such as biomolecule-detection and drug delivery. In this work, we employed mesoscopic coarse-grained simulations to study ovispirin-1 and lysozyme protein coronas on bare gold nanoparticles. Our study showed that protein corona formation is governed by protein-surface and protein-protein interactions, as well as the surface hydrophobic effect. The corona structure was found to be dependent on protein types and the size of nanoparticles. Ovispirin proteins form homogeneous single-layered adsorption in comparison with the lysozyme's inhomogeneous multilayered aggregates on gold NP surfaces. The decrease in nanoparticle size leads to more angular degrees of freedom for protein adsorption orientation. Subsequent atomistic molecular dynamics simulations further demonstrate the loss of secondary structure of ovispirin upon adsorption and the heterogeneity of its local structure.Asymmetric synthesis of quinoline-naphthalene atropisomers with fully blocked ortho positions has been developed by a two-step strategy, which contains a chiral phosphoric acid-catalyzed Povarov reaction and a DDQ oxidation reaction. This method provides facile access to diverse functionalized quinoline-naphthalene atropisomers with one or two chiral axes in excellent yields (≤98%) and excellent enantioselectivities (≤99% ee).Photoexcitation can drastically modify potential energy surfaces of materials, allowing access to hidden phases. SrTiO3 (STO) is an ideal material for photoexcitation studies due to its prevalent use in nanostructured devices and its rich range of functionality-changing lattice motions. Recently, a hidden ferroelectric phase in STO was accessed through weak terahertz excitation of polarization-inducing phonon modes. In contrast, whereas strong laser excitation was shown to induce nanostructures on STO surfaces and control nanopolarization patterns in STO-based heterostructures, the dynamic pathways underlying these optically induced structural changes remain unknown. Here nonadiabatic quantum molecular dynamics reveals picosecond amorphization in photoexcited STO at temperatures as low as 10 K. The three-stage pathway involves photoinduced charge transfer and optical phonon activation followed by nonlinear charge and lattice dynamics that ultimately lead to amorphization. This atomistic understanding could guide not only rational laser nanostructuring of STO but also broader "quantum materials on demand" technologies.We designed and synthesized a series of derivatives containing the right-side DFGH-ring structure of physalin-type natural products, decorated with a hydrophobic substituent. The synthetic scheme utilizes a highly efficient, one-pot protocol for simultaneous construction of the GH-ring system, promoted by HF/pyridine. https://www.selleckchem.com/products/irak-1-4-inhibitor-i.html Among the compounds synthesized, 5d inhibited TNF-α-stimulated NF-κB activation with similar potency to physalin B.State-to-state dynamics of the benchmark hydrogen exchange reaction H + H2 (v = 0-4, j = 0-3) → H2 (v', j') + H is investigated with the aid of the real wave packet approach of Gray and Balint-Kurti (J. Chem. Phys. 1998, 108, 950-962) and electronic ground BKMP2 potential energy surface of Boothroyd et al. (J. Chem. Phys. 1996, 104, 7139-7152). Initial state-selected and product state-resolved reaction probabilities, integral cross section, and product diatom vibrational and rotational level populations at a few collision energies are reported to elucidate the energy disposal mechanism. State-specific thermal rate constants are also calculated and compared with the available literature results. Coriolis coupling terms of the nuclear Hamiltonian are included, and calculations are parallelized over the helicity quantum number, Ω'. Attempts are made, in particular, to study the effect of reagent vibrational and rotational excitations on the dynamical attributes. It is found that the calculations become computationally expensive with reagent vibrational and rotational excitation. Reagent vibrational excitation is found to enhance the reactivity and has significant impact on the energy disposal to the vibrational and rotational degrees of freedom of the product. The interplay of reagent translational and vibrational energy on the product vibrational distribution unfolds an important aspect of the energy disposal mechanism. The effect of reagent rotation on the state-to-state dynamics is found not to be very significant, and the weak effect turns out to be specific to v'.Gas phase spectroscopy is a powerful tool for examining fundamental chemical structures and properties free from solvent molecules. We developed a gas-phase resonance Raman spectroscopy combined with IR-laser ablation of a droplet beam, which allowed us to elucidate local structures around chromophores in gas-phase proteins and DNAs. To demonstrate the potential of this approach, we applied this method to myoglobin, one of the heme proteins, and elucidated its structures in the gas phase and in aqueous solution. The experimental spectra are compared with calculated spectra of stable heme structures for the structural determination. These results show the oxidation/spin states of the Fe atom in myoglobin in the gas phase and were compared with the aqueous solution from the obtained resonant Raman spectra. The present method gives an important tool to investigate the gas-phase structure of large biomolecules.Ion identity and concentration influence the solubility of macromolecules. To date, substantial effort has been focused on obtaining a molecular level understanding of specific effects for anions. By contrast, the role of cations has received significantly less attention and the underlying mechanisms by which cations interact with macromolecules remain more elusive. To address this issue, the solubility of poly(N-isopropylacrylamide), a thermoresponsive polymer with an amide moiety on its side chain, was studied in aqueous solutions with a series of nine different cation chloride salts as a function of salt concentration. Phase transition temperature measurements were correlated to molecular dynamics simulations. The results showed that although all cations were on average depleted from the macromolecule/water interface, more strongly hydrated cations were able to locally accumulate around the amide oxygen. These weakly favorable interactions helped to partially offset the salting-out effect. Moreover, the cations approached the interface together with chloride counterions in solvent-shared ion pairs. Because ion pairing was concentration-dependent, the mitigation of the dominant salting-out effect became greater as the salt concentration was increased. Weakly hydrated cations showed less propensity for ion pairing and weaker affinity for the amide oxygen. As such, there was substantially less mitigation of the net salting-out effect for these ions, even at high salt concentrations.The field of bioactive lipids is ever expanding with discoveries of novel lipid molecules that promote human health. Adopting a lipidomic-assisted approach, two new families of previously unrecognized saturated hydroxy fatty acids (SHFAs), namely, hydroxystearic and hydroxypalmitic acids, consisting of isomers with the hydroxyl group at different positions, were identified in milk. Among the various regio-isomers synthesized, those carrying the hydroxyl at the 7- and 9-positions presented growth inhibitory activities against various human cancer cell lines, including A549, Caco-2, and SF268 cells. In addition, 7- and 9-hydroxystearic acids were able to suppress β-cell apoptosis induced by proinflammatory cytokines, increasing the possibility that they can be beneficial in countering autoimmune diseases, such as type 1 diabetes. 7-(R)-Hydroxystearic acid exhibited the highest potency both in cell growth inhibition and in suppressing β-cell death. We propose that such naturally occurring SHFAs may play a role in the promotion and protection of human health.Brasilane-type sesquiterpenes have been known for a long time, but their biosynthetic pathways and mechanisms remain elusive. Recently, two groups independently characterized a Trichoderma terpene cyclase that produces trichobrasilenol, a brasilane-type sesquiterpene, and a plausible biosynthetic pathway was proposed based on isotopic labeling experiments. In the proposed mechanism, the characteristic brasilane-type 5/6 bicyclic skeleton is synthesized from a 5/7/3 tricyclic intermediate via a complicated concerted reaction, including six chemical events of C-C σ bond metathesis and rearrangements, ring-contraction, π bond formation, and regioselective hydroxylation. However, our density functional theory (DFT) calculations do not support this mechanism. On the basis of DFT calculations, we propose a new pathway for trichobrasilenol biosynthesis, involving a multistep carbocation cascade in which cyclopropylcarbinyl cations in equilibrium with homoallyl cations play a pivotal role. This pathway and mechanism is in good agreement with previous biosynthetic studies on brasilane-type compounds and related terpenoids, including isotope-labeling experiments and byproducts analysis.Bimetallic Pt-based alloys have drawn considerable attention in the last decades as catalysts in proton-exchange membrane fuel cells (PEMFCs) because they closely fulfill the two major requirements of high performance and good stability under operating conditions. Pt3Fe, Pt3Co, and Pt3Ni stand out as major candidates, given their good activity toward the challenging oxygen reduction reaction (ORR). The common feature across catalysts based on 3d-transition metals and their alloys is magnetism. Ferromagnetic spin-electron interactions, quantum spin-exchange interactions (QSEIs), are one of the most important energetic contributions in allowing milder chemisorption of reactants onto magnetic catalysts, in addition to spin-selective electron transport. The understanding of the role played by QSEIs in the properties of magnetic 3d-metal-based alloys is important to design and develop novel and effective electrocatalysts based on abundant and cheap metals. We present a detailed theoretical study (via density functional theory) on the most experimentally explored bimetallic alloys Pt3M (M = V, Cr, Mn, Fe, Co, Ni, and Y)(111). The investigation starts with a thorough structural study on the composition of the layers, followed by a comprehensive physicochemical description of their resistance toward segregation and their chemisorption capabilities toward hydrogen and oxygen atoms. Our study demonstrates that Pt3Fe(111), Pt3Co(111), and Pt3Ni(111) possess the same preferential multilayered structural organization, known for exhibiting specific magnetic properties. The specific role of QSEIs in their catalytic behavior is justified via comparison between spin-polarized and non-spin-polarized calculations.Hydrothermal and solid-state reaction methods are commonly used to prepare the delafossite CuCrO2 photocatalyst. It has been reported that the photocatalytic performances of CuCrO2 samples prepared by these methods are quite different. In order to explore the possible influence of different preparation processes on the photocatalytic performance and the corresponding improvement strategies, this work compares the microstructure and physicochemical properties of the samples prepared by these two methods on the basis of optimizing the process conditions. A CuCrO2 sample prepared by a hydrothermal method is characterized by high purity, low crystallinity, small grain size, and relatively higher photocatalytic activity. A CuCrO2 sample prepared by a solid-state reaction method is characterized by low purity, high crystallinity, large grain size, and relatively lower photocatalytic activity. In combination with DFT calculations, it is confirmed that the CuCrO2 sample prepared by a solid-state reaction method contains a certain amount of interstitial oxygens.