Search results for "Molecular structure"
showing 10 items of 1246 documents
Construction and expression of a dual vector for chemo-enzymatic synthesis of plant indole alkaloids inEscherichia coli
2010
A dual vector (pQE-70-STR1-SG) containing coding regions of strictosidine synthase (STR1, EC 4.3.3.2) and strictosidine glucosidase (SG, EC 3.2.1.105) from the Indian medicinal plant Rauvolfia serpentina was constructed. Functional expression of the vector in Escherichia coli cells (M15 strain) was proven by isolation of prepurified enzyme extracts, which show both STR1 and SG activities. Incubation of the enzyme in the presence of tryptamine and secologanin delivered the indole alkaloid cathenamine, demonstrating functional co-expression of both STR1- and SG-cDNAs. Cathenamine reduction by sodium borohydride leading to tetrahydroalstonine revealed the chemo-enzymatic indole alkaloid synthe…
A Molecular Electron Density Theory Study of the Reactivity of Azomethine Imine in [3+2] Cycloaddition Reactions
2017
The electronic structure and the participation of the simplest azomethine imine (AI) in [3+2] cycloaddition (32CA) reactions have been analysed within the Molecular Electron Density Theory (MEDT) using DFT calculations at the MPWB1K/6-311G(d) level. Electron localisation function (ELF) topological analysis reveals that AI has a pseudoradical structure, while the conceptual DFT reactivity indices characterise this TAC as a moderate electrophile and a good nucleophile. The non-polar 32CA reaction of AI with ethylene takes place through a one-step mechanism with low activation energy, 5.3 kcal/mol-1. A bonding evolution theory (BET) study indicates that this reaction takes place through a non-…
Calix[4]arene-functionalized naphthalene and perylene imide dyes.
2002
[reaction: see text] Calix[4]arenes bearing one, two, or four 1,8-naphthyl imide groups at the wide rim and bis-calix[4]arenes connected via perylene-bisimide dye spacers have been synthesized. The low-temperature NMR spectrum of the tetranaphthylimide suggests, in agreement with a crystal structure, a C2-symmetrical pinched cone conformation stabilized via face-to-face pi-pi interactions between opposite naphthylimide groups. UV-vis and fluorescence studies have been carried out for the perylene bis-calix[4]arene dyes.
Fasciola spp: Mapping of the MF6 epitope and antigenic analysis of the MF6p/HDM family of heme-binding proteins
2017
MF6p/FhHDM-1 is a small cationic heme-binding protein which is recognized by the monoclonal antibody (mAb) MF6, and abundantly present in parenchymal cells and secreted antigens of Fasciola hepatica. Orthologs of this protein (MF6p/HDMs) also exist in other causal agents of important foodborne trematodiasis, such as Clonorchis sinensis, Opisthorchis viverrini and Paragonimus westermani. Considering that MF6p/FhHDM-1 is relevant for heme homeostasis in Fasciola and was reported to have immunomodulatory properties, this protein is expected to be a useful target for vaccination. Thus, in this study we mapped the epitope recognized by mAb MF6 and evaluated its antigenicity in sheep. The sequenc…
Potential of human serum albumin as chiral selector of basic drugs in affinity electrokinetic chromatography-partial filling technique
2006
The enantiomeric resolution of compounds using HSA by means of affinity EKC (AEKC)-partial filling technique is the result of a delicate balance between different experimental variables such as protein concentration, running pH (background electrophoretic buffer (BGE), protein, and compound solutions), and plug length. In this paper, the possibility of using HSA as chiral selector for enantioseparation of 28 basic drugs using this methodology is studied. The effect of the physicochemical parameters, the structural properties of compounds, and compound-HSA protein binding percentages over their chiral resolution with HSA is outlined. Based on the results obtained, a decision tree is proposed…
Pearl-necklace structures of molecular brushes with rigid backbone under poor solvent conditions: A simulation study
2010
Bottle-brush polymers, where flexible side chains containing N=20 to 50 effective monomers are grafted to a rigid backbone, are studied by molecular dynamics simulations, varying the grafting density σ and the solvent quality. Whereas for poor solvents and large enough σ the molecular brush is a cylindrical object, homogeneous in axial direction, for intermediate values of σ an axially inhomogeneous structure of "pearl-necklace" type is formed. The "pearls," however, have a strongly nonspherical ellipsoidal shape, due to the fact that several side chains cluster together in one pearl, qualitatively consistent with predictions of Sheiko et al. [Eur. Phys. J. E 13, 125 (2004)] We analyze the …
De novo design of protein kinase inhibitors by in silico identification of hinge region-binding fragments.
2013
Protein kinases constitute an attractive family of enzyme targets with high relevance to cell and disease biology. Small molecule inhibitors are powerful tools to dissect and elucidate the function of kinases in chemical biology research and to serve as potential starting points for drug discovery. However, the discovery and development of novel inhibitors remains challenging. Here, we describe a structure-based de novo design approach that generates novel, hinge-binding fragments that are synthetically feasible and can be elaborated to small molecule libraries. Starting from commercially available compounds, core fragments were extracted, filtered for pharmacophoric properties compatible w…
Highly Selective Detection of Nerve‐Agent Simulants with BODIPY Dyes
2014
Two chromo-fluorogenic probes, each based on the boron dipyrromethene core, have been developed for the detection of nerve-agent mimics. These chemosensors display both a color change and a significant enhancement of fluorescence in the presence of diethylcyanophosphonate (DCNP) and diisopropylfluorophosphate (DFP). No interference from other organophosphorus compounds or acids has been observed. Two portable chemosensor kits have been developed and tested to demonstrate its practical application in real-time monitoring.
Synthesis of 3-azabicyclo[3.2.2]nonanes and their antiprotozoal activities.
2015
Several bicyclic compounds, 3-azabicyclo[3.2.2]nonanes, have been prepared. The new compounds were tested for their activities against one strain of the causative organism of Malaria tropica, Plasmodium falciparum K1, which is resistant against chloroquine and pyrimethamine. In addition, their cytotoxicity and their activity against the pathogen of the East African form of sleeping sickness, Trypanosoma brucei rhodesiense, were investigated. Structure-activity relationships are discussed considering data of readily prepared compounds. For the first time, a distinct in vivo activity was observed against Plasmodium berghei in a mouse model. The active compound was further investigated.
Gold-Catalyzed Intramolecular Hydroamination of o-Alkynylbenzyl Carbamates: A Route to Chiral Fluorinated Isoindoline and Isoquinoline Derivatives
2013
Enantiomerically pure fluorinated isoindoline and dihydroisoquinoline scaffolds have been prepared through a diastereoselective addition of fluorinated nucleophiles to Ellman’s N-(tert-butanesulfinyl)imines followed by a sequence of Sonogashira cross-coupling/gold(I)-catalyzed cycloisomerization of the corresponding carbamate. A more favored 5-exo-dig mechanism was observed mainly due to an electronic effect of the fluorinated group.