Search results for "cleavage"
showing 10 items of 281 documents
Photochemical Synthesis and Reactivity of New Chloro-Bridged Complexes with Tungstenocene (η5-C5H5)(η5-C5H4PPh2)WClX (X = H, Cl) and Tetracarbonylmet…
1999
Chloro-bridged bimetallic complexes (η5-C5H5)[η5-C5H4PPh2M′(CO)4]W(μ-Cl)X [X = Cl (3), × = H (4); M′ = Cr, W] were prepared by photochemical irradiation of (η5-C5H5)[η5-C5H4PPh2M′(CO)5]WClX [X = Cl (1), × = H (2); M′ = Cr, W]. The reactivity of the chloro-bridged complexes towards Lewis bases was studied; by exposure to CO or phosphanes, a facile cleavage of the chloro bridge accompanied by regio- and stereospecific coordination at M′ occurs. The X-ray structure of complex 3 (M′ = W) is reported.
Reaktive Metabolite cancerogener polycyclischer Kohlenwasserstoffe: Synthese und Abfangreaktion von 9-Hydroxybenzo[a]pyren-4,5-oxid
1985
Le compose du titre est prepare a partir de l'acetate-9 de benzo [a] pyrene et piege par l'ethanethiol. Mecanismes
Alternative Polyadenylation Events Contribute to the Induction of NF-ATc in Effector T Cells
1999
Abstract The transcription factor NF-ATc is synthesized in three prominent isoforms. These differ in the length of their C terminal peptides and mode of synthesis. Due to a switch from the use of a 3′ polyA site to a more proximal polyA site, NF-ATc expression switches from the synthesis of the two longer isoforms in naive T cells to that of short isoform A in T effector cells. The relative low binding affinity of cleavage stimulation factor CstF-64 to the proximal polyA site seems to contribute to its neglect in naive T cells. These alternative polyadenylation events ensure the rapid accumulation of high concentrations of NF-ATc necessary to exceed critical threshold levels of NF-ATc for g…
ADAM10 in Alzheimer's disease: Pharmacological modulation by natural compounds and its role as a peripheral marker.
2019
Abstract Alzheimer’s disease (AD) represents a global burden in the economics of healthcare systems. Amyloid-β (Aβ) peptides are formed by amyloid-β precursor protein (AβPP) cleavage, which can be processed by two pathways. The cleavage by the α-secretase A Disintegrin And Metalloprotease 10 (ADAM10) releases the soluble portion (sAβPPα) and prevents senile plaques. This pathway remains largely unknown and ignored, mainly regarding pharmacological approaches that may act via different signaling cascades and thus stimulate non-amyloidogenic cleavage through ADAM10. This review emphasizes the effects of natural compounds on ADAM10 modulation, which eventuates in a neuroprotective mechanism. M…
DNA binding, nuclease activity, DNA photocleavage and cytotoxic properties of Cu(II) complexes of N-substituted sulfonamides.
2013
Abstract Ternary copper(II) complexes [Cu(NST)2(phen)] (1) and [Cu(NST)2(NH3)2]·H2O (2) [HNST = N-(4,5-dimethylthiazol-2-yl)naphthalene-1-sulfonamide] were prepared and characterized by physico-chemical techniques. Both 1 and 2 were structurally characterized by X-ray crystallography. The crystal structures show the presence of a distorted square planar CuN4 geometry in which the deprotonated sulfonamide, acting as monodentate ligand, binds to the metal ion through the thiazole N atom. Both complexes present intermolecular π–π stacking interactions between phenanthroline rings (compound 1) and between naphthalene rings (compound 2). The interaction of the complexes with CT DNA was studied b…
Stereoselective Synthesis of (+)-11βH,13-Dihydroestafiatin, (+)-11βH,13-Dihydroludartin, (−)-Compressanolide, and (−)-11βH,13-Dihydromicheliolide fro…
2002
Starting from 2 and 3, obtained from santonin (1), we have synthesized natural guaianolides 4-7. Chemoselective epoxidation of 2 gave (+)-11betaH,13-dihydroestafiatin (4), and epoxidation of 3 followed by regioselective elimination of the hydroxyl group afforded (+)-11betaH,13-dihydroludartin (5). Sharpless' mild regioselective ring-opening of 4 and 5 followed by hydrogenolysis yielded (-)-compressanolide (6) and (-)-11betaH,13-dihydromicheliolide (7), respectively.
Time-scale of deformation and intertectonic phases revealed by P-T-D-t relationships in the orogenic middle crust of the Orlica-Śnieżnik Dome, Polish…
2014
A section of the orogenic middle crust (Orlica-nienik Dome, Polish/Czech Central Sudetes) was examined to constrain the duration and significance of deformation (D) and intertectonic (I) phases. In the studied metasedimentary synform, three deformation events produced an initial subhorizontal foliation S1 (D-1), a subsequent subvertical foliation S2 (D-2) and a late subhorizontal axial planar cleavage S3 (D-3). The synform was intruded by pre-, syn- and post-D-2 granitoid sheets. Crystallization-deformation relationships in mica schist samples document I1-2 garnet-staurolite growth, syn-D-2 staurolite breakdown to garnet-biotite-sillimanite/andalusite, I2-3 cordierite blastesis and late-D-3…
Estimation of the density of the protocatechuate-degrading bacterial community in soil by real-time PCR
2008
Summary The β-ketoadipate pathway is the major route for degradation of aromatic compounds by various soil microorganisms. Protocatechuate 3,4-dioxygenase, a key enzyme of this pathway and which is encoded by pcaGH genes, catalyses the ring cleavage of protocatechuate. Microorganisms harbouring pcaGH genes are widely distributed in the environment but little is known about their relative abundance within the total microflora. Hence, this paper reports the development of a real-time PCR assay to quantify the bacterial pcaH sequence that encodes the β sub-unit of the protocatechuate 3,4-dioxygenase. This real-time PCR assay was linear over seven orders of magnitude with a calculated efficienc…
Synergy between quantum dots and 1,10-phenanthroline–copper(ii) complex towards cleaving DNA
2011
We have found that the DNA cleaving activity of quantum dots and 1,10-phenanthroline-Cu(II) complex is significantly enhanced when they are combined.
A Post-Labeling Approach for the Characterization and Quantification of RNA Modifications Based on Site-Directed Cleavage by DNAzymes
2011
Deoxyribozymes or DNAzymes are small DNA molecules with catalytic activity originating from in vitro selection experiments. Variants of the two most popular DNAzymes with RNase activity, the 10-23 DNAzyme and the 8-17 DNAzyme, promote efficient in vitro cleavage of the phosphodiester bond in at least 11 out of 16 possible dinucleotide permutations. Judicious choice of the sequences flanking the active core of the DNAzymes permits to direct cleavage activity with high sequence specificity. Here, the harnessing of these features for the analysis of RNA nucleotide modifications by a post-labeling approach is described in detail. DNAzymes are designed such that RNase cleavage is directed precis…