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471.
Wavepacket Splitting and Two‐Pathway Deactivation in the Photoexcited Visual Pigment Isorhodopsin 下载免费PDF全文
Dr. Dario Polli Dr. Oliver Weingart Dr. Daniele Brida Emiliano Poli Margherita Maiuri Dr. Katelyn M. Spillane Prof. Andrea Bottoni Dr. Philipp Kukura Prof. Richard A. Mathies Prof. Giulio Cerullo Dr. Marco Garavelli 《Angewandte Chemie (International ed. in English)》2014,53(9):2504-2507
Isorhodopsin is the visual pigment analogue of rhodopsin. It shares the same opsin environment but it embeds 9‐cis retinal instead of 11‐cis. Its photoisomerization is three times slower and less effective. The mechanistic rationale behind this observation is revealed by combining high‐level quantum‐mechanical/molecular‐mechanical simulations with ultrafast optical spectroscopy with sub‐20 fs time resolution and spectral coverage extended to the near‐infrared. Whereas in rhodopsin the photoexcited wavepacket has ballistic motion through a single conical intersection seam region between the ground and excited states, in isorhodopsin it branches into two competitive deactivation pathways involving distinct conical intersection funnels. One is rapidly accessed but unreactive. The other is slower, as it features extended steric interactions with the environment, but it is productive as it follows forward bicycle pedal motion. 相似文献
472.
Ciavatta ML Lopez Gresa MP Gavagnin M Manzo E Mollo E D'Souza L Cimino G 《Molecules (Basel, Switzerland)》2006,11(10):808-816
Chemical analysis of the secondary metabolite pattern of the sacoglossan mollusc Elysia cf. expansa, collected along South Indian coasts, showed the presence of the typical Caulerpa-derived sesquiterpene caulerpenyne (1) and two new minor co- occurring metabolites, the compounds dihydrocaulerpenyne (4) and expansinol (5). The chemical characterization of these molecules, structurally related to 1, is reported. 相似文献
473.
Wen Zhang Margherita Gavagnin Yue-Wei Guo Ernesto Mollo Guido Cimino 《Tetrahedron》2007,63(22):4725-4729
Chemical analysis of the secondary metabolite pattern of the nudibranch Hexabranchus sanguineus collected from the South China Sea revealed the presence of both sesquiterpenoids and diterpenoids, exhibiting very different structural features. Two new molecules, compounds 1 and 4, were isolated together with known compounds 2 and 3, and chemically characterized. This is the first report of terpenoids from H. sanguineus. The remarkable diversity of metabolites possessed by H. sanguineus supports some recent phylogenetic studies that place the mollusc near the steam of the dorid nudibranch tree. 相似文献
474.
Claudia Albertini Marina Naldi Sabrina Petralla Silvia Strocchi Daniela Grifoni Barbara Monti Manuela Bartolini Maria Laura Bolognesi 《Molecules (Basel, Switzerland)》2021,26(4)
Despite Alzheimer’s disease (AD) incidence being projected to increase worldwide, the drugs currently on the market can only mitigate symptoms. Considering the failures of the classical paradigm “one target-one drug-one disease” in delivering effective medications for AD, polypharmacology appears to be a most viable therapeutic strategy. Polypharmacology can involve combinations of multiple drugs and/or single chemical entities modulating multiple targets. Taking inspiration from an ongoing clinical trial, this work aims to convert a promising cromolyn–ibuprofen drug combination into single-molecule “codrugs.” Such codrugs should be able to similarly modulate neuroinflammatory and amyloid pathways, while showing peculiar pros and cons. By exploiting a linking strategy, we designed and synthesized a small set of cromolyn–ibuprofen conjugates (4–6). Preliminary plasma stability and neurotoxicity assays allowed us to select diamide 5 and ethanolamide 6 as promising compounds for further studies. We investigated their immunomodulatory profile in immortalized microglia cells, in vitro anti-aggregating activity towards Aβ42-amyloid self-aggregation, and their cellular neuroprotective effect against Aβ42-induced neurotoxicity. The fact that 6 effectively reduced Aβ-induced neuronal death, prompted its investigation into an in vivo model. Notably, 6 was demonstrated to significantly increase the longevity of Aβ42-expressing Drosophila and to improve fly locomotor performance. 相似文献
475.
Margherita Moreno Monica Sani Guido Raos Stefano V. Meille Raffaella Giavazzi Alessandro Volonterio 《Tetrahedron》2006,62(43):10171-10181
The synthesis of trifluoromethyl (Tfm) analogs of known nanomolar matrix metalloproteinases (MMPs) inhibitors has been performed. The synthetic protocol is based on a moderately stereoselective aldol reaction of trifluoropyruvate with an N-acyl-oxazolidin-2-thione for the construction of the core α-Tfm-malic unit. Both the diastereomeric forms of the target α-Tfm-malic hydroxamates showed micromolar inhibitory potency toward MMP-2 and 9, according to zymographic tests, with a substantial drop with respect to the parent unfluorinated compounds. We also report some molecular modeling results, which provide a rationale for the experimental findings. 相似文献
476.
Cardullo F Donati D Fusillo V Merlo G Paio A Salaris M Solinas A Taddei M 《Journal of combinatorial chemistry》2006,8(6):834-840
One of the still unresolved problems in parallel synthesis is the availability of a general and rapid method for the transformation of a primary amine into the corresponding secondary amine without the issue of polyalkylation. Following the Fukuyama method, which is based on the alkylation of o-nitrobenzenesulfonamides, followed by removal of the sulfonyl group, we have developed a simple protocol which can be easily applied to parallel synthesis making use of supported reagents and scavengers. To verify the robustness of the method, a small representative array of secondary amines have been prepared. Moreover, taking advantage of the possibility to use different supported reagents in the same pot, we also prepared, starting from primary amines, a series of differently substituted tertiary amines. 相似文献
477.
Margherita Solci 《Mathematical Methods in the Applied Sciences》2012,35(5):598-620
In this paper, we study a homogenization problem for perimeter energies in highly contrasted media; the analysis of the previous paper is carried out by removing the hypothesis that the perforated medium Rn ? E is composed of disjoint compact components. Assuming E to be the union of a finite number N of connected components E1, … ,EN, the Γ‐limit F is a multiphase energy with a ‘decoupled’ surface part, obtained by homogenization from the surface tensions in each E j, a trivial bulk term obtained as a weak limit, and a further interacting term between the phases, involving an asymptotic formula for a family minimum problems on invading an asymptotic formula for a family of minimum problems on invading domains with prescribed boundary conditions. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
478.
Margherita Nolasco Gabriella Tarantello 《Calculus of Variations and Partial Differential Equations》1999,9(1):31-94
For a selfdual model introduced by Hong-Kim-Pac [18] and Jackiw-Weinberg [19] we study the existence of double vortex-condensates“bifurcating” from the symmetric vacuum state as the Chern-Simons coupling parameter k tends to zero. Surprisingly, we show a connection between the asymptotic behavior of the given double vortex as with the existence of extremal functions for a Sobolev inequality of the Moser-Trudinger's type on the flat 2-torus ([22], [1] and [15]). In fact, our construction yields to a “best” minimizing sequence for the (non-coercive) associated extremal problem, in the sense that, the infimum is attained if and only if the given minimizing sequence admits a convergent subsequence. Received: March 3, 1998 / Accepted October 23, 1998 相似文献
479.
480.