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Jesús Ferrando-Soria Consuelo Yuste Miguel Julve Oscar Fabelo Catalina Ruiz-Pérez Rafael Ruiz-García Joan Cano 《Inorganica chimica acta》2010,363(8):1666-11281
Two novel dinuclear copper(II) complexes of formulae [Cu2(tren)2(bpda)](ClO4)4 (2) and [Cu2(tren)2(tpda)](ClO4)4 (3) containing the tripodal tris(2-aminoethyl)amine (tren) terminal ligand and the 4,4′-biphenylenediamine (bpda) and 4,4″-p-terphenylenediamine (tpda) bridging ligands have been synthesized and structurally, spectroscopically, and magnetically characterized. Their experimentally available electronic spectroscopic and magnetic properties have been reasonably reproduced by DFT and TDDFT calculations. Single crystal X-ray diffraction analysis of 2 shows the presence of dicopper(II) cations where the bpda bridging ligand adopts a bismonodentate coordination mode toward two [Cu(tren)]2+ units with an overall non-planar, orthogonal anti configuration of the N-Cu-N threefold axis of the trigonal bipyramidal CuII ions and the biphenylene group. The electronic absorption spectra of 2 and 3 in acetonitrile reveal the presence of four moderately weak d-d transitions characteristic of a slightly distorted trigonal bipyramid stereochemistry of the CuII ions. TDDFT calculations on 2 identify these transitions as those taking place between the four lower-lying, doubly occupied a2 (dyz)2, b2 (dxz)2, b1 (dxy)2, and a1 (dx2-y2)2 orbitals and the upper, singly occupied a1 (dz2)1 orbital of each trigonal bipyramidal CuII ion. Variable-temperature magnetic susceptibility measurements of 2 and 3 show the occurrence of moderate (J = −8.5 cm−1) to weak intramolecular antiferromagnetic couplings (J = −2.0 cm-1) [H = −JS1·S2 with S1 = S2 = SCu = ½] inspite of the relatively large copper-copper separation across the para-substituted biphenylene- (r = 12.3 Å) and terphenylenediamine (r = 16.4 Å) bridges, respectively. DFT calculations on 2 and 3 support the occurrence of a spin polarization mechanism for the propagation of the exchange interaction between the two unpaired electrons occupying the dz2 orbital of each trigonal bipyramidal CuII ion through the predominantly π-type orbital pathway of the oligo-p-phenylenediamine bridges, as reported earlier for the parent compound [Cu2(tren)2(ppda)](ClO4)4·2H2O (1) with the 1,4-phenylenediamine (ppda) bridging ligand. Finally, a rather slow exponential decay of the antiferromagnetic coupling (-J) with the number of phenylene repeat units, -(C6H4)n- (n = 1-3), has been found both experimentally and theoretically along this series of oligo-p-phenylenediamine-bridged dicopper(II) complexes. These results further support the ability of linear π-conjugated oligo-p-phenylene spacers to transmit the exchange interaction between the unpaired electrons of the two CuII centers with intermetallic distances in the range of 7.5-16.4 Å. 相似文献
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Salgado MC Justo SV Joaquim LF Fazan R Salgado HC 《American journal of physiology. Heart and circulatory physiology》2006,290(3):H1059-H1063
Because the regulation of vascular function involves complex mutual interactions between nitric oxide (NO) synthase (NOS) and cyclooxygenase (COX) products, we examined the contribution of NO and prostanoids derived from the COX pathway in modulating aortic baroreceptor resetting during an acute (30 min) increase in arterial pressure in anesthetized rats. Increase in pressure was induced either by administration of the nonselective NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) or aortic coarctation (COA) with or without treatment with the COX inhibitor indomethacin (INDO) or the selective neuronal NOS inhibitor 1-(2-trifluoromethylphenyl)imidazole (TRIM). The activity of the aortic depressor nerve and arterial pressure were simultaneously recorded, and the degree of resetting was determined by the shift of the pressure-nerve activity curve using the ratio [delta systolic pressure at 50% of maximum baroreceptor activity/delta systolic pressure] x 100. The magnitude of pressure rise was similar in the different groups (59 +/- 6, 53 +/- 5, 53 +/- 5, 45 +/- 5, 49 +/- 3, and 41 +/- 3 mmHg for COA, L-NAME, INDO+COA, INDO+L-NAME, TRIM+COA, and TRIM+INDO+COA, respectively, P = 0.27). The degree of resetting that occurred with L-NAME or COA combined with treatment with TRIM was attenuated compared with COA alone (7 +/- 4, 5 +/- 2, and 31 +/- 6%, respectively, P = 0.04). INDO failed to influence baroreceptor resetting to higher pressure but prevented L-NAME- and TRIM-induced effects (20 +/- 7, 21 +/- 8, and 32 +/- 6% for INDO+COA, INDO+L-NAME, and INDO+TRIM+COA, respectively; P = 0.38). Baroreceptor gain was affected only by l-NAME. These findings indicate that NO, probably from neuronal origin, may exert stimulatory influence on the degree of rapid baroreceptor resetting to hypertension that involves COX-derived prostanoids. 相似文献
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Lienqueo ME Mahn A Navarro G Salgado JC Perez-Acle T Rapaport I Asenjo JA 《Journal of molecular recognition : JMR》2006,19(4):260-269
Hydrophobic interaction chromatography (HIC) is an important technique for the purification of proteins. In this paper, we review three different approaches for predicting protein retention time in HIC, based either on a protein's structure or on its amino-acidic composition, and we have extended one of these approaches. The first approach correlates the protein retention time in HIC with the protein average surface hydrophobicity. This methodology is based on the protein three-dimensional structure data and considers the hydrophobic contribution of the exposed amino acid residues as a weighted average. The second approach, which we have extended, is based on the high correlation level between the average surface hydrophobicity of a protein's hydrophobic interacting zone and its retention time in HIC. Finally, a third approach carries out a prediction of the average surface hydrophobicity of a protein, using only its amino-acidic composition, without knowing its three-dimensional structure. These models would make it possible to test different operating conditions for the purification of a target protein by computer simulations, and thus make it easier to select the optimal conditions, contributing to the rational design and optimization of the process. 相似文献
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Arvizu F Aguilera A Salgado LM 《Differentiation; research in biological diversity》2006,74(6):305-312
The development of the hydra's head and its hypostome has been studied at the molecular level. Many genes have been cloned from hydra as potential candidates that control the development of its head. Much work was performed on the mechanisms controlling expression of these genes in the position-dependent manner. Moreover, there have been data to support the involvement of three main signaling pathways that involve PKC, SRC, and PI3K kinases in the regulation of the head formation and in the expression of several head-specific genes. In this report, we present data supporting the participation of these three signaling pathways on the development of the hypostome. We used grafting experiments and inhibitors of the specific kinases to show the participation of these enzymes in hypostome formation. From our results, we postulate that these signal transduction pathways regulate the very early stages of the head development, most likely at the point when the cells start to differentiate to form the head organizer. 相似文献
109.
Carrera I Sueiro C Molist P Holstein GR Martinelli GP Rodríguez-Moldes I Anadón R 《Cell and tissue research》2006,323(2):273-281
The present immunocytochemical study provides evidence of a previously unrecognized, rich, γ-aminobutyric acid (GABA)-ergic
innervation of the pineal organ in the dogfish (Scyliorhinus canicula). In this elasmobranch, the pineal primordium is initially detected at embryonic stage 24 and grows to form a long pineal
tube by stage 28. Glutamic acid decarboxylase (GAD)-immunoreactive (-ir) fibers were first observed at stage 26, and by stage
28, thin GAD-ir fibers were detectable at the base of the pineal neuroepithelium. In pre-hatchling embryos, most fibers gave
rise to GAD-ir boutons that were localized in the basal region of the neuroepithelium, although a smaller number of labeled
terminals ascended to the pineal lumen. A few pale GAD-ir perikarya were observed within the pineal organ of stage 29 embryos,
but GAD-ir perikarya were not observed at other developing stages or in adults. In contrast, GABA immunocytochemistry revealed
the presence of GABAergic perikarya and fibers in the pineal organ of late stage embryos and adults. Although high densities
of GABAergic cells were observed in the paracommissural pretectum, posterior tubercle, and tegmentum of dogfish embryos (regions
previously demonstrated to contain pinealopetal cells), the presence of GABA-ir perikarya in the pineal organ strongly suggests
that the rich GABAergic innervation of the elasmobranch pineal organ is intrinsic. This contrasts with the central origin
of GABAergic fibers in the pineal gland of some mammals.
This work was supported by the Spanish Education and Science Ministry and FEDER (BXX2000-0453-C02 and BFU2004-03313/BF1),
the Xunta de Galicia (PGIDT99BIO20002), and NIH/NIDCD awards R01 DC01705 and P01 DC01837 (to G.R.H.). 相似文献
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