Search results for "Epoxide"
showing 10 items of 251 documents
Differential subcellular localization of endogenous and transfected soluble epoxide hydrolase in mammalian cells: evidence for isozyme variants
1999
AbstractEndogenous, constitutive soluble epoxide hydrolase in mice 3T3 cells was localized via immunofluorescence microscopy exclusively in peroxisomes, whereas transiently expressed mouse soluble epoxide hydrolase (from clofibrate-treated liver) accumulated only in the cytosol of 3T3 and HeLa cells. When the C-terminal Ile of mouse soluble epoxide hydrolase was mutated to generate a prototypic putative type 1 PTS (-SKI to -SKL), the enzyme targeted to peroxisomes. The possibility that soluble epoxide hydrolase-SKI was sorted slowly to peroxiosmes from the cytosol was examined by stably expressing rat soluble epoxide hydrolase-SKI appended to the green fluorescent protein. Green fluorescent…
Identification and Characterization of a Novel Epoxide Hydrolase From Mouse Liver Microsomes
1982
A new microsomal epoxide hydrolase (mEH2) has been identified and characterized. This enzyme has properties which distinguish it from previously described cytosolic (cEH) or membrane-bound (mEH1) epoxide hydrolases. The enzyme is an integral microsomal protein which is not dissociated from the membrane by repeated washing, high ionic strength salt, or chaotropic agent solutions, or by sonication. It is very different from the normally described microsomal epoxide hydrolase (mEH1) as shown by its different substrate specificity and kinetic properties and by immunological criteria. In contrast to the hitherto described microsomal epoxide hydrolase, mEH1, the new enzyme effectively catalyzes t…
Rat Cytosolic Epoxide Hydrolase
1986
Rat liver microsomal and cytosolic epoxide hydrolase may be distinguished through differences in substrate specificity: styrene 7,8-oxide is preferentially hydrolyzed by the microsomal form, while trans-stilbene oxide is the prefered substrate for cytosolic epoxide hydrolase. Large interindividual differences in the specific activity of SpragueDawley (outbred strain) liver cytosolic epoxide hydrolase were observed, varying from 2 to 77 pmol/min x mg protein. Interindividual variations were much lower for microsomal epoxide hydrolase. The specific activity of Fischer F-344 (inbred strain) liver cytosolic epoxide hydrolase varied only by a factor of 2. The specific activity of cytosolic epoxi…
Modulation of Epdxide Hydrolase Activity; Effect on the Activation of Benzo Cal Pyrene and Its Covalent Binding to Dna in the Nucleus
1982
Benzo[a]pyrene (BP), a model polycyclic aromatic hydrocarbon mutagen and carcinogen, requires bioactivation for the expression of its carcinogenic and mutagenic properties. This process occurs in multiple steps, the initial step being a conversion of BP to epoxide(s) by membrane-bound monooxygenases. The subsequent disposition of these electrophilic species can be directed towards toxic or nontoxic endpoints, depending upon the relative preponderance of several enzymatic and nonenzymatic processes within the cell. Epoxides formed from BP can rearrange to form phenols, be conjugated to glutathione, be converted by epoxide hydrolase to dihydrodiols or bind to cellular macromolecules (Jerina a…
A combined experimental and theoretical study of the thermal [3+2] cycloaddition of carbonyl ylides with activated alkenes
2018
International audience; 4-Benzoyl-3,5-diaryltetrahydrofuran-2,2-dicarbonitriles were first synthesized from 2,2-dicyano-3-aryloxiranes and chalcones at toluene reflux; the 4,5-cis products proved to be predominantly formed and were isolated. Whereas shortened reaction times were observed by using microwave irradiation or catalytic cuprous chloride, no significant stereoselectivity change was in general noticed. Reacting 2,2-dicyano-3-aryloxiranes with 2-cyclopentenone next afforded 3-aryl-4-oxohexahydro-1H-cyclopenta[c]furan-1,1-dicarbonitriles, and the endo stereoisomers were isolated. That no stereoselectivity change was noticed in the presence of cuprous chloride rather suggests an impac…
Influence of the level of cytosolic epoxide hydrolase on the induction of sister chromatid exchanges by trans-beta-ethylstyrene 7,8-oxide in human ly…
1991
Abstract trans -β-Ethylstyrene 7,8-oxide, a substrate of cytosolic epoxide hydrolase, and 4-fluorochalcone oxide, an inhibitor of this enzyme, were investigated on induction of sister chromatid exchanges (SCE) in human lymphocytes. Both epoxides enhanced the frequency of SCE. 4-Fluorochalcone oxide at low concentration (2.5μM) inhibited cytosolic epoxide hydrolase activity towards trans -β-ethylstyrene 7,8-oxide in lymphocytes by 74% and had no effect on glutathione transferase activity using this substrate. At this concentration it did not induce SCE itself, but it potentiated the effect of trans -β-ethylstyrene 7,8-oxide several fold. In lymphocytes from different subjects, the number of …
Diastereo- and enantioselective synthesis of orthogonally protected 2,4-diaminocyclopentanecarboxylates: a flip from beta-amino- to beta,gamma-diamin…
2007
Conformationally restricted, orthogonally protected 2,4-diaminocarboxylates with a cyclopentane skeleton were efficiently synthesized from beta-lactam 6, the syntheses involving strategies of diastereoselective epoxidation of the beta-lactam and the corresponding monoprotected amino esters with opposite selectivities followed by regioselective opening of the oxirane ring with sodium azide. The enantiomers were also prepared. This new class of compounds can be regarded not only as conformationally constrained beta,gamma-diamino acid derivatives but also as potential functionalized carbocyclic nucleoside precursors.
From an epoxide monomer toolkit to functional PEG copolymers with adjustable LCST behavior.
2011
The lower critical solution temperature (LCST) behavior of novel poly(ethylene glycol) (PEG)-based copolymers bearing multiple functional groups, obtained by anionic ring-opening (co)polymerization (AROP), has been investigated. Variable comonomer ratios of ethylene oxide (EO) and the corresponding oxiranes isopropylidene glyceryl glycidyl ether (IGG), ethoxyl vinyl glycidyl ether (EVGE), allyl glycidyl ether (AGE), or N,N-dibenzyl amino glycidyl (DBAG), particularly designed to implement functional groups at the PEG backbone, were found to influence the LCST behavior. Sharp transitions from translucent to opaque solutions, comparable to other well-established stimuli-responsive polymers, w…
Long-Chain Alkyl Epoxides and Glycidyl Ethers: An Underrated Class of Monomers.
2020
Long-chain epoxides and specifically alkyl glycidyl ethers represent a class of highly hydrophobic monomers for anionic ring-opening polymerization (AROP), resulting in apolar aliphatic polyethers. In contrast, poly(ethylene glycol) is known for its high solubility in water. The combination of hydrophobic and hydrophilic monomers in block and statistical copolymerization reactions enables the synthesis of amphiphilic polyethers for a wide range of purposes, utilizing micellar interactions in aqueous solutions, e.g., viscosity enhancement of aqueous solutions, formation of supramolecular hydrogels, or for polymeric surfactants. Controlled polymerization of these highly hydrophobic long-chain…
Polymerization of Ethylene Oxide, Propylene Oxide, and Other Alkylene Oxides: Synthesis, Novel Polymer Architectures, and Bioconjugation.
2015
The review summarizes current trends and developments in the polymerization of alkylene oxides in the last two decades since 1995, with a particular focus on the most important epoxide monomers ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO). Classical synthetic pathways, i.e., anionic polymerization, coordination polymerization, and cationic polymerization of epoxides (oxiranes), are briefly reviewed. The main focus of the review lies on more recent and in some cases metal-free methods for epoxide polymerization, i.e., the activated monomer strategy, the use of organocatalysts, such as N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs) as well as phosphazen…