Search results for "Interactions"
showing 10 items of 1963 documents
Gaia DR2 reveals a star formation burst in the disc 2-3 Gyr ago
2019
We use Gaia DR2 magnitudes, colours and parallaxes for stars with G<12 to explore a 15-dimensional space that includes simultaneously the initial mass function (IMF) and a non-parametric star formation history (SFH) for the Galactic disc. This inference is performed by combining the Besancon Galaxy Model fast approximate simulations (BGM FASt) and an approximate Bayesian computation algorithm. We find in Gaia DR2 data an imprint of a star formation burst 2-3 Gyr ago, in the Galactic thin disc domain, and a present star formation rate (SFR) of about 1 Msun. Our results show a decreasing trend of the SFR from 9-10 Gyr to 6-7 Gyr ago. This is consistent with the cosmological star formation …
CGCG 480-022: A Distant Lonesome Merger?
2006
[EN]We present a complete analysis, which includes morphology, kinematics, stellar populations, and N-body simulations, of CGCG 480-022, the most distant (cz = 14,317 km s-1) isolated galaxy studied so far in such detail. The results all support the hypothesis that this galaxy has suffered a major merger event with a companion of ~0.1 times its mass. Morphology reveals the presence of a circumnuclear ring and possibly further ring debris. The radial velocity curve looks symmetrical, while the velocity dispersion increases with radius, reaching values that do not correspond to a virialized system. Moreover, this galaxy deviates significantly from the fundamental plane and the Faber-Jackson r…
Binding isotope effects as a tool for distinguishing hydrophobic and hydrophilic binding sites of HIV-1 RT.
2014
The current treatment for HIV-1 infected patients consists of a cocktail of inhibitors, in an attempt to improve the potency of the drugs by adding the possible effects of each supplied compound. In this contribution, nine different inhibitors of HIV-1 RT, one of the three key proteins responsible for the virus replication, have been selected to develop and test a computational protocol that allows getting a deep insight into the inhibitors’ binding mechanism. The interaction between the inhibitors and the protein have been quantified by computing binding free energies through FEP calculations, while a more detailed characterization of the kind of inhibitor–protein interactions is based on …
The introduction of fluorine atoms or trifluoromethyl groups in short cationic peptides enhances their antimicrobial activity
2006
The effect of introducing fluorine atoms or trifluoromethyl groups in either the peptidic chain or the C-terminal end of cationic pentapeptides is reported. Three series of amide and ester peptides were synthesised and their antimicrobial properties evaluated. An enhanced activity was found in those derivatives whose structure contained fluorine, suggesting an increase in their hydrophobicity.
A Discrete P⋅⋅⋅II⋅⋅⋅P Assembly: The Large Influence of Weak Interactions on the31P NMR Spectra of Phosphane–Diiodine Complexes
2006
Thioethers, except derivatives of [7-R-7,8-C2B9H11] , are more weakly coordinating ligands than phosphanes. This difference is evidenced by the I I distances in the spokeshaped charge-transfer (CT) complexes R2S·I2 and R3P·I2 (Figure 1). The I I distance is sensitive to the strength of the interaction between the s* LUMO orbital on I2 and the HOMO orbital of the donor atom: the stronger the donor, the longer the I I distance. In these spoke CT complexes, the I I distance varies from 3.2 0.2 7 in R3P·I2 adducts [5] to 2.80 0.05 7 in R2S·I2 adducts, [6] indicating the weaker donor character of the thioether group. Whereas extended I2 arrays, spoke adducts of I2, polyiodides, and other structu…
α-Adrenoceptor Interaction of Tetrandrine and Isotetrandrine in the Rat: Functional and Binding Assays
1998
Abstract The action of 1S,1′S-tetrandrine, a bisbenzyltetrahydroisoquinoline alkaloid, on α1-adrenoceptors has been compared with that of its isomer 1R,1′S-isotetrandrine. The work includes binding assays to analyse the affinity of these products for the [3H]prazosin binding site of rat cerebral cortical membranes and functional studies on rat isolated aorta to examine the effects of both alkaloids on intracellular calcium processes related or not to α-adrenoceptor activation. A radioligand receptor-binding study showed that both compounds interacted with the α1-adrenoceptors displacing [3H]prazosin from the specific binding site. The Ki values (inhibition constants) were 0.69±0.12 and 1.6±…
Specific interactions of monotetrahydrofuranic annonaceous acetogenins as inhibitors of mitochondrial complex I.
2000
Annonaceous acetogenins (ACG) are a wide group of cytotoxic compounds isolated from plants of the Annonaceae family. Some of them are promising candidates to be a future new generation of antitumor drugs due to the ability to inhibit the NADH:ubiquinone oxidoreductase of the respiratory chain (mitochondrial complex I), main gate of the energy production in the cell. ACG are currently being tested on standard antitumor trials although little is known about the structure activity relationship at the molecular level. On recent studies, the relevance of several parts of the molecule for the inhibitory potency has been evaluated. Due to the great diversity of skeletons included in this family of…
N-Benzyl Residues as the P1′ Substituents in Phosphorus-Containing Extended Transition State Analog Inhibitors of Metalloaminopeptidases
2020
Peptidyl enzyme inhibitors containing an internal aminomethylphosphinic bond system (P(O)(OH)-CH2-NH) can be termed extended transition state analogs by similarity to the corresponding phosphonamidates (P(O)(OH)-NH). Phosphonamidate pseudopeptides are broadly recognized as competitive mechanism-based inhibitors of metalloenzymes, mainly hydrolases. Their practical use is, however, limited by hydrolytic instability, which is particularly restricting for dipeptide analogs. Extension of phosphonamidates by addition of the methylene group produces a P-C-N system fully resistant in water conditions. In the current work, we present a versatile synthetic approach to such modified dipeptides, based…
Mononuclear rearrangement of heterocycles in zwitterionic micelles of amine oxide surfactants.
2012
Abstract Rate constants for the mononuclear rearrangement (MRH) of Z -phenylhydrazones of some 5-substituted-3-benzoyl-1,2,4-oxadiazoles in water have been measured in the presence of zwitterionic micelles. The use of micellized N -tetradecyl- N , N -dimethylamineoxide (C 14 DMAO) as the reaction medium allowed to solubilize the otherwise water-insoluble oxadiazoles. Micellar rate effects were analyzed by using a simple pseudo-phase model and compared with those obtained in non-ionic micelles (Triton X-100). Evidence that both the rate of the rearrangement reaction and the binding of the substrates to the micelles are mainly governed by substrate hydrophobicity is obtained. The disagreement…
Stacking of Sterically Congested Trifluoromethylated Aromatics in their Crystals – The Role of Weak F···π or F···F Contacts
2020
European journal of organic chemistry : EurJOC 2020(38), 6073-6077 (2020). doi:10.1002/ejoc.202001008