Conjugate addition with organometallics and nitration of nitroxide (aminoxyl) free radicals. Synthesis of potentially useful cross-linking spin label reagents

1988 ◽  
pp. 2905-2911 ◽  
Author(s):  
Kálmán Hideg ◽  
H. Olga Hankovszky ◽  
H. Anna Halász ◽  
Pál Sohár
Keyword(s):  
Free Radicals ◽  
Spin Label ◽  
Conjugate Addition ◽  
Cross Linking

scholarly journals Oilseeds as Functional Foods: Content and Composition of Many Phytochemicals and Therapeutic Alternatives

2021 ◽  
Author(s):  
Aicha O. Cherif
Keyword(s):  
Free Radicals ◽  
Cardiovascular Diseases ◽  
Lipid Oxidation ◽  
Human Health ◽  
Functional Foods ◽  
Cross Linking ◽  
Minor Components ◽  
Active Constituents ◽  
Dna Mutations ◽  
Therapeutic Alternatives

Oilseeds composition has been studied extensively, but recently it has been thoroughly investigated considering especially the phytochemicals representing the minor components. This interest is connected with the activity of such compounds against cardiovascular diseases, lipid oxidation, protein cross-linking and DNA mutations and hemostasis function, which prevent the attack of biomolecules by free radicals. This chapter book could aim to give an overview of the different uses of several oilseeds as bioactive foods, focusing on their active constituents (phytosterols, polyphenols, tocopherols, tocotrienols, and carotenoids) and their content in oilseeds. We will also focus on the beneficial aspects of theses nutraceuticals in human health.

Radical conjugate addition of ambiphilic fluorinated free radicals

Tetrahedron ◽  
2013 ◽  
Vol 69 (29) ◽  
pp. 5920-5926 ◽  
Author(s):  
Coralie De Schutter ◽  
Emmanuel Pfund ◽  
Thierry Lequeux
Keyword(s):  
Free Radicals ◽  
Conjugate Addition

scholarly journals KINETIC STUDIES OF A REDOX POLYMERIZATION

1953 ◽  
Vol 31 (1) ◽  
pp. 13-22
Author(s):  
R. M. Brown ◽  
C. A. Winkler
Keyword(s):  
Free Radicals ◽  
Kinetic Studies ◽  
Activation Energies ◽  
Polymer Chains ◽  
Cross Linking ◽  
Gel Point ◽  
Emulsion System ◽  
Redox Polymerization ◽  
Termination Process

Kinetic studies of a redox-initiated polymerization have indicated activation energies of 9.7 kcal. per mole for the decomposition of the initiating system, approximately 6 kcal. per mole for the propagation reaction, and 9.0 kcal. per mole for the consumption of MTM-4 in the emulsion system. Lower polymerization temperatures raised the gel point without shortening the polymer chains, apparently by decreasing the proportion of cross-linking to propagation reactions. Two types of nonmercaptan termination have been found to occur to appreciable extents: mutual termination of free radicals and a termination process involving the emulsifier.

scholarly journals The action of dilute aqueous NN-dimethylhydrazine on bacterial cell walls

1969 ◽  
Vol 113 (1) ◽  
pp. 183-189 ◽  
Author(s):  
J. C. Anderson ◽  
A. R. Archibald ◽  
J Baddiley ◽  
M. J. Curtis ◽  
N. Barbara Davey
Keyword(s):  
Molecular Weight ◽  
Free Radicals ◽  
High Molecular Weight ◽  
Bacterial Cell ◽  
Cell Walls ◽  
Cross Linking ◽  
Gram Positive ◽  
Teichoic Acids ◽  
Gram Positive Bacteria ◽  
Almost All

1. Walls of certain Gram-positive bacteria dissolved on incubation with dilute aqueous NN-dimethylhydrazine in the presence of air, by a reaction that probably involves free radicals. 2. Under the conditions described, the soluble products from the peptidoglycan were almost all non-diffusible. After brief incubation of walls of some organisms with reagent, part of the peptidoglycan component was obtained as a high-molecular-weight gel, the viscosity of which was rapidly decreased by incubation with lysozyme. 3. The extent to which peptidoglycan dissolved varied with different organisms, depending possibly on the extent of cross-linking, but the nature of the bonds that were destroyed has not been established. 4. Teichoic acids and polysaccharides were solubilized by this treatment and could be isolated in high overall yield. 5. The procedure is valuable in the examination of the distribution of heteropolymers in walls, and has been used to show that the polysaccharide present in walls of Lactobacillus arabinosus 17–5 is phosphorylated and may account for 20% of the total phosphate of the wall.

scholarly journals Effector-sensitive cross-linking of phosphorylase b kinase by the novel cross-linker 4-phenyl-1,2,4-triazoline-3,5-dione

1998 ◽  
Vol 331 (1) ◽  
pp. 137-141 ◽  
Author(s):  
Nancy A. AYERS ◽  
Owen W. NADEAU ◽  
Mark W. READ ◽  
Partha RAY ◽  
Gerald M. CARLSON
Keyword(s):  
Gel Electrophoresis ◽  
Conjugate Addition ◽  
Structural Features ◽  
Subunit Composition ◽  
Side Chain ◽  
Cross Linking ◽  
Initial Reaction ◽  
The Novel ◽  
Cross Linker ◽  
Novel Protein

The dienophile 4-phenyl-1,2,4-triazoline-3,5-dione (PTD) was identified as a novel protein cross-linker, and utilized as a conformational probe of phosphorylase b kinase (PhK), a hexadecameric enzyme with the subunit composition (αβγδ)4. In its reaction with this enzyme, PTD produced five major cross-linked conjugates as resolved by denaturing gel electrophoresis: αβ, βγγ, αγ and a doublet of differently migrating homodimers, ββ1 and ββ2. Cross-linking in the presence of six different activators of the kinase targeted to its various subunits caused substantial changes in the amounts of three of the conjugates. The formation of αγ was increased by all of the activators but the largest enhancement was caused by exogenous Ca2+/calmodulin. All except one of the activators decreased the amount of βγγ formed, with Mg2+ having the greatest effect, and all except two increased the amount of ββ1, with Mg2+ again having the largest influence. From the overall similarity of the changes in cross-linking by PTD induced by the various activators, we conclude that, even though they are targeted to different sites and subunits, they induce activated conformations of PhK that have certain structural features in common. Regarding the mechanism of cross-linking by PTD, its reaction with a model nucleophile suggests that its initial reaction with a side chain nucleophile of PhK involves a 1,4-conjugate addition to form a urazole adduct, with the secondary cross-linking reaction occurring through an as yet unknown pathway.

Influence of Calcium Ions on the Plant Cell Surface: Membrane Fusions and Conformational Changes

1974 ◽  
Vol 32 ◽  
pp. 154-155
Author(s):  
D. James Morré ◽  
Charles E. Bracker ◽  
William J. VanDerWoude
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Conformational Changes ◽  
Calcium Ions ◽  
Surface Membrane ◽  
Carboxyl Groups ◽  
Cross Linking ◽  
Ultrastructural Evidence ◽  
Glycine Max L ◽  
Wall Extensibility

Calcium ions in the concentration range 5-100 mM inhibit auxin-induced cell elongation and wall extensibility of plant stems. Inhibition of wall extensibility requires that the tissue be living; growth inhibition cannot be explained on the basis of cross-linking of carboxyl groups of cell wall uronides by calcium ions. In this study, ultrastructural evidence was sought for an interaction of calcium ions with some component other than the wall at the cell surface of soybean (Glycine max (L.) Merr.) hypocotyls.

Embedding Procedure for Water Swollen Samples

1970 ◽  
Vol 28 ◽  
pp. 504-505
Author(s):  
Ann M. Thomas ◽  
Virginia Shemeley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Exchange ◽  
Structural Changes ◽  
Cross Linking ◽  
Ion Exchange Resins ◽  
Transmission Electron ◽  
First Pass ◽  
Exchange Resins

Those samples which swell rapidly when exposed to water are, at best, difficult to section for transmission electron microscopy. Some materials literally burst out of the embedding block with the first pass by the knife, and even the most rapid cutting cycle produces sections of limited value. Many ion exchange resins swell in water; some undergo irreversible structural changes when dried. We developed our embedding procedure to handle this type of sample, but it should be applicable to many materials that present similar sectioning difficulties.The purpose of our embedding procedure is to build up a cross-linking network throughout the sample, while it is in a water swollen state. Our procedure was suggested to us by the work of Rosenberg, where he mentioned the formation of a tridimensional structure by the polymerization of the GMA biproduct, triglycol dimethacrylate.

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