Search results for "COPP"
showing 10 items of 3147 documents
The Arabidopsis Copper Transporter COPT1 Functions in Root Elongation and Pollen Development
2004
Copper plays a dual role in aerobic organisms, as both an essential and a potentially toxic element. To ensure copper availability while avoiding its toxic effects, organisms have developed complex homeostatic networks to control copper uptake, distribution, and utilization. In eukaryotes, including yeasts and mammals, high affinity copper uptake is mediated by the Ctr family of copper transporters. This work is the first report on the physiological function of copper transport in Arabidopsis thaliana. We have studied the expression pattern of COPT1 in transgenic plants expressing a reporter gene under the control of the COPT1 promoter. The reporter gene is highly expressed in embryos, tric…
DISPOSITIVO DATORE DI COPPIA PER PROVA DI INGRANAGGI MECCANICI, ROTISMI MECCANICI E SIMILI
2021
La presente invenzione riguarda un dispositivo che ha lo scopo di sottoporre a prova rotismi meccanici per la trasmissione di elevata potenza. L’impiego di tale dispositivo sostituisce, quindi, l’uso di freni di prova il cui impiego per elevate potenze risulta costoso e i cui ingombri sono rilevanti.
Coordinative Versatility of Guanazole [3,5‐Diamino‐1,2,4‐triazole]: Synthesis, Crystal Structure, EPR, and Magnetic Properties of a Dinuclear and a L…
2006
New complexes with guanazole (3,5-diamino-1,2,4-triazole = Hdatrz), [Cu 2 (Hdatrz) 2 (μ-OH 2 )(H 2 O) 4 (SO 4 )](SO 4 )·3.5H 2 O (1) and [Cu 3 (Hdatrz) 4 (μ-Cl) 2 (H 2 O) 4 (SO 4 ) 2 ]·11.4H 2 O (2), have been prepared and structurally characterized. Complex 1 is a noncentrosymmetric dinuclear compound in which the cop-per(II) ions are bridged by two triazole ligands and one μ-OH 2 molecule, with a Cu(1)···Cu(2) distance of 3.4945(8) A. The chromophores are Cu(1)N 2 O 2 O' (square pyramidal), and Cu(2)N 2 O 2 O'O" (octahedral). Complex 2 has a linear trinuclear copper(II) structure, with two crystallographically independent copper(II) atoms. Neighboring copper(II) ions are linked by two tri…
Copper-catalysed enantioselective Michael addition of malonic esters to β-trifluoromethyl-α,β-unsaturated imines
2017
[EN] Copper triflate-BOX complexes catalyse the enantioselective conjugate addition of methyl malonate to beta-trifluoromethyl-alpha,beta-unsaturated imines to give the corresponding enamines bearing a trifluoromethylated stereogenic centre with good yields, and diastereo- and enantioselectivities. The usefulness of the method has been shown with the synthesis of optically active beta-trifluoromethyl delta-amino esters and optically active trifluoromethyl piperidones.
Highly enantioselective copper(I)-catalyzed conjugate addition of 1,3-diynes to a,b-unsaturated trifluoromethyl ketones
2015
[EN] The conjugate diynylation of a,b-unsaturated trifluoromethyl ketones is carried out in the presence of a low catalytic load (2.5 mol%) of a copper(I)–MeOBIPHEP complex, triethylamine and a terminal 1,3-diyne. Pre-metalation of the terminal 1,3-diyne with stoichiometric or higher amounts of dialkylzinc reagent is not required. The corresponding internal diynes bearing a propargylic stereogenic center are obtained with good yields and excellent enantioselectivities.
Highly enantioselective copper(I)-catalyzed conjugate addition of terminal alkynes to 1,1-difluoro-1-(phenylsulfonyl)-3-en-2-ones: new ester/amide su…
2013
A highly enantioselective copper-catalyzed conjugate alkynylation of monoactivated enones, namely 1,1-difluoro-1-(phenylsulfonyl)-3-en-2-ones, is described. The reaction products are obtained with good yields and excellent enantioselectivities (from 92 to 99% ee). The β-alkynylated difluoro(phenylsulfonyl) ketones can be converted into the corresponding β-alkynylated difluoro- and trifluoromethyl ketones, esters and amides. This is the first example on the use of 1,1-difluoro-1-(phenylsulfonyl)-3-en-2-ones as substrates in an enantioselective reaction, which have been shown to be new ester/amide surrogates.
Ferromagnetic copper(II)–copper(II) interaction in a single chlorido and dicyanamido bridged mixed–valence copper(I/II) 2D polymer generated by in si…
2015
A mixed-valence 2-D Cu(I/II) complex, [{Cu(II)(dmen)(μ-Cl)(μ1,5-dca)}{Cu(I)(μ1,5-dca)}]n (1) (dmen = N,N-dimethylethylenediamine, dca = dicyanamide = [N(CN)2]−), has been synthesized by in situ partial reduction of Cu(II) to Cu(I) using benzoin (2-hydroxy-1,2-di(phenyl)ethanone) as reductant. Complex 1 was characterized by spectroscopic techniques, single crystal X-ray diffraction, and low temperature magnetic measurements. Structural investigation reveals that 1 represents a mixed-valence 2-D coordination polymer formed by parallel 1-D [Cu(II)(dmen)(Cl)Cu(I)(μ1,5-dca)2]n chains running along the b axis, where chloride bridges Cu(II) ions of adjacent polymers through long connections (2.840…
Efficient two-step synthesis of water soluble BODIPY–TREN chemosensors for copper(II) ions
2017
Two simple fluorescent sensors for Cu(II) ions were synthesized in two reaction steps, using recently developed C–H functionalization reactions for boron dipyrrins, starting from a standard 8-aryl-BODIPY dye and a tris(2-aminoethyl)amine (TREN) ligand. At pH 5, the resulting BODIPY–TREN conjugates are demonstrated to be promising, highly selective, water soluble, Cu(II) sensors that can permeate the cell membrane. crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: Bram Verbelen (ORCID) identifier: Wim Dehaen (ORCID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: Thi…
Synthesis and copper-mediated nuclease activity of a tetracationic tris(2,2′-bipyridine) ligand
2009
Abstract We report herein the synthesis of a novel tetracationic tris(2,2′-bipyridine) ligand 4 . We show that this ligand metalated with copper(II), and in the presence of ascorbate as a reducing agent, strongly damages pUC18 plasmid DNA. Copper complex formation was demonstrated by ESI-MS (electrospray ionization-mass spectrum) at a 1:3 ligand to metal ratio. Binding of both 4 and its copper(II) complex to CT-DNA (calf thymus DNA) was characterized by viscosimetry, thermal denaturation and fluorescence-based competition assays. The viscosimetric data indicated that 4 and its copper(II) complex bind DNA through partial intercalation and thermal denaturation studies revealed a significant i…
Switch between tyrosinase and catecholoxidase activity of scorpion hemocyanin by allosteric effectors
2008
AbstractPhenoloxidases and hemocyanins have similar type 3 copper centers although they perform different functions. Hemocyanins are oxygen carriers, while phenoloxidases (tyrosinase/catecholoxidase) catalyze the initial step in melanin synthesis. Tyrosinases catalyze two subsequent reactions, whereas catecholoxidases catalyze only the second one. Recent results indicate that hemocyanins can also function as phenoloxidases and here we show for the first time that hemocyanin can be converted to phenoloxidase. Furthermore, its substrate specificity can be switched between catecholoxidase and tyrosinase activity depending on effectors such as hydroxymethyl-aminomethan (Tris) and Mg2+-ions. Thi…