Search results for "CLEAVAGE"
showing 10 items of 281 documents
Metallomacrocycles with metalmetal bonds: synthesis, characterization and electrochemistry of [(P)SnRe(CO)5]BF4 and [{(P)Sn}2Re(CO)4]BF4 derivatives…
1996
Abstract The synthesis and characterization of bimetallic and trimetallic porphyrins of the type [(P)SnRe(CO) 5 ]BF 4 and [{(P)Sn} 2 Re(CO) 4 ]BF 4 are reported where P is the dianion of tetra- p -tolyporphyrin (TpTP) or tetra- m -tolyporphyrin (TmTP). These metal-metal bonded complexes were synthesized by reaction of Re 2 (CO) 10 with the corresponding (P)SnCl 2 derivatives in 1,2-dichlorobenzene followed by a reaction with NaBF 4 or TBABF 4 in toluene to give the BF − 4 salt. Each compound was characterized by a variety of spectroscopic and electrochemical techniques while the structures were assigned on the basis of FAB mass spectral data and by comparison of their physicochemical proper…
A new strategy in selecting oocytes using cumulus cells analysis of specific molecules of the apoptotic pathway, according to the ability to reach bl…
2015
Study question: The aim of the research was to investigate the apoptosis rate of individual cumulus cell–oocyte complexes (COC), associated to the level of p-Akt, to verify the difference between oocytes who produce embryos able to reach the blastocyst stage compared with embryos arrested during the in vitro colture. Summary answer: It was demonstrated that DNA fragmentation in cumulus cells was remarkably lower in patients who achieved a pregnancy after ICSI cycles, related to the quality of oocytes and embryos. Akt pathway plays a critical role in the regulation of cell survival, and most growth factors activate this pathway. What is known already: Studies on oocyte maturation have shown …
The use of morphokinetics as a predictor of embryo implantation.
2011
Background Time-lapse observation presents an opportunity for optimizing embryo selection based on morphological grading as well as providing novel kinetic parameters, which may further improve accurate selection of viable embryos. The objective of this retrospective study was to identify the morphokinetic parameters specific to embryos that were capable of implanting. In order to compare a large number of embryos, with minimal variation in culture conditions, we have used an automatic embryo monitoring system. Methods Using a tri-gas IVF incubator with a built-in camera designed to automatically acquire images at defined time points, we have simultaneously monitored up to 72 individual emb…
Functionalized Dialdehydes as Promising Scaffolds for Access to Heterocycles and β-Amino Acids: Synthesis of Fluorinated Piperidine and Azepane Deriv…
2017
Functionalized dialdehydes are considered important substrates that can be transformed into various substituted heterocyclic, alicyclic, and polysubstituted compounds. Here, we report a robust stereocontrolled procedure for the synthesis of novel functionalized trifluoromethyl-containing piperidine and azepane derivatives, based on oxidative ring cleavage of the C=C bond of diversely substituted cycloalkenes, followed by reductive ring closure of the diformyl intermediates in the presence of fluorine-containing amines.
Diversity-Oriented Stereocontrolled Synthesis of Some Piperidine- and Azepane-Based Fluorine-Containing β-Amino Acid Derivatives
2020
AbstractStructural diversity-oriented synthesis of some azaheterocyclic β-amino acid derivatives has been accomplished by selective functionalization of readily available cyclodienes. The stereocontrolled synthetic concept was based on the oxidative ring cleavage of unsaturated cyclic β-amino acids derived from cycloalkadiene, followed by ring closing with double reductive amination, which furnished some conformationally restricted β-amino acid derivatives with a piperidine or azepane core.
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…
Synthesis of various natural 8,12-elemanolides from artemisin
1989
Abstract This paper describes the chemical transformations of artemisin into various natural 8,12-elemanolides.
ChemInform Abstract: Rhodium Catalyzed Oxidative Coupling of Salicylaldehydes with Diazabicyclic Olefins: A One-Pot Strategy Involving Aldehyde C-H C…
2013
The title reaction involves the first example of ring opening and ring closing of bicyclic hydrazines (I) via metal catalyzed oxidative coupling reaction.
Proteolytic cleavage of soybean Bowman-Birk inhibitor monitored by means of high-performance capillary electrophoresis. Implications for the mechanis…
1996
The hydrolysis of the soybean Bowman-Birk inhibitor in the presence of catalytic amounts of bovine trypsin and the formation of the non-covalent enzyme-inhibitor complex with an equimolar amount of enzyme are monitored by means of high-performance capillary electrophoresis (HPCE). The inhibitor is cleaved in the trypsin-reactive and more slowly in the chymotrypsin-reactive subdomain. HPCE proves itself as the only reliable analytical tool to monitor these reactions in clear contrast to classical electrophoretic, chromatographic and enzymatic methods. The most efficient separation of the intact and the two active site cleaved forms of the inhibitor was achieved in borate buffer at pH 10.0. T…
Der (2-Phenyl-2-trimethylsilyl)ethyl-(PTMSE)-Ester – eine neutral spaltbare Carboxyschutzgruppe/The (2-Phenyl-2-trimethylsiylyl)ethyl (PTMSE) Ester –…
2002
(2-Phenyl-2-trimethylsilyl)ethyl (PTMSE) esters of aminoacids and peptides are stable under the conditions of hydrogenolytic cleavage of benzoxycarbonyl(Z) and benzyl ester groups, base-induced removal of Fmoc groups, palladium(0)-catalyzed removal of allyloxycarbonyl (Aloc) and even acidolytic cleavage of Boc groups. PTMSE esters are also stable under the conditions of peptide condensation reactions. The PTMSE ester is selectively cleaved by treatment with tetrabutylammonium fluoride (TBAF) trihydrate in dichloromethane, i. e. under almost neutral conditions, within a few minutes and, therefore, considered a valuable novel carboxy protecting group.