Dynamic and interaction of cytochrome c with Pf1 virus

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em BioOrgânicaCytochrome c is a positive protein and the Pf1 virus surface is negative forging strong electrostatic complex. When a critical ratio concentration of Cytochrome c and Pf1 virus is achieved a spontaneous complex is formed. The maximum association upon addition of cytochrome c to Pf1 solutions is about 1700 cytochrome c molecules to one Pf1 virion particle. The effect of univalent salt concentration on protein polyelectrolyte complex formation was measured by Dynamic Light Scattering. Complex disaggregation occurred when monovalent salt concentration increased. The assembly process was also observed by NMR at low salt concentration in the system. The aggregate can be gradually dissociated in order to enable NMR spectra acquisition. Depending on virus/cytochorme c ratio or ionic strength concentration we could shift from free protein and virus in solution to transient binding or fully immobilized complex. It was possible to map the most affected regions of the oxidized heme cytochrome c, with chemical shift variation due to the binding to Pf1 virus, during salt titration. Dry and liquid samples of Cytochrome c and Pf1 at different ratios and pH were studied and evaluated by Atomic Force Microscopy. The system was also studied above the critical salt concentration of complex dissociation by PGSEDOSY NMR. A gradual decrease in the translational diffusion coefficient of cytochrome was caused by higher content of Pf1 virus in solution. We conclude that a strong electrostatic correlation between pf1 virus and cytochrome c occurs even after complex dissociation

The solvation and redox behavior of mixed ligand copper(II) complexes of acetylacetonate and aromatic diimines in ionic liquids

The behavior of two cationic copper complexes of acetylacetonate and 2,2'-bipyridine or 1,10-phenanthroline, [Cu(acac)(bipy)]Cl (1) and [Cu(acac)(phen)]Cl (2), in organic solvents and ionic liquids, was studied by spectroscopic and electrochemical techniques. Both complexes showed solvatochromism in ionic liquids although no correlation with solvent parameters could be obtained. By EPR spectroscopy rhombic spectra with well-resolved superhyperfine structure were obtained in most ionic liquids. The spin Hamiltonian parameters suggest a square pyramidal geometry with coordination of the ionic liquid anion. The redox properties of the complexes were investigated by cyclic voltammetry at a Pt electrode (d = 1 mm) in bmimBF(4) and bmimNTf(2) ionic liquids. Both complexes 1 and 2 are electrochemically reduced in these ionic media at more negative potentials than when using organic solvents. This is in agreement with the EPR characterization, which shows lower A(z) and higher g(z) values for the complexes dissolved in ionic liquids, than in organic solvents, due to higher electron density at the copper center. The anion basicity order obtained by EPR is NTf2-, N(CN)(2)(-), MeSO4- and Me2PO4-, which agrees with previous determinations. (C) 2013 Elsevier B.V. All rights reserved

The solvation and electrochemical behavior of copper acetylacetonate complexes in ionic liquids

The behavior of copper(II) complexes of pentane-2,4-dione and 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, [Cu(acac)(2) (1) and [Cu(HFacac)(2)(H2O)] (2), in ionic liquids and molecular organic solvents, was studied by spectroscopic and electrochemical techniques. The electron paramagnetic resonance characterization (EPR) showed well-resolved spectra in most solvents. In general the EPR spectra of [Cu(acac)(2)] show higher g(z) values and lower hyperfine coupling constants, A(z), in ionic liquids than in organic solvents, in agreement with longer Cu-O bond lengths and higher electron charge in the copper ion in the ionic liquids, suggesting coordination of the ionic liquid anions. For [Cu(HFacac)(2)(H2O)] the opposite was observed suggesting that in ionic liquids there is no coordination of the anions and that the complex is tetrahedrically distorted. The redox properties of the Cu(II) complexes were investigated by cyclic voltammetry (CV) at a Pt electrode (d = 1 mm), in bmimBF(4) and bmimNTf(2) ionic liquids and, for comparative purposes, in neat organic solvents. The neutral copper(II) complexes undergo irreversible reductions to Cu(I) and Cu(0) species in both ILs and common organic solvents (CH2Cl2 or acetonitrile), but, in ILs, they are usually more easier to reduce (less cathodic reduction potential) than in the organic solvents. Moreover, 1 and 2 are easier to reduce in bmimNTf(2) than in bmimBF(4) ionic liquid. (C) 2013 Elsevier B.V. All rights reserved

Use of organomolybdenum compounds for promoted hydrolysis of phosphoester bonds in aqueous media

Trabalho apresentado no 6th EuCheMs Chemistry Congress, 11-15 de setembro de 2016, Sevilha, EspanhaN/

Exploring the therapeutic potential of Cu(II)-complexes with ligands derived from pyridoxal

Three new copper(II) complexes formulated as [Cu(L)(X)], where X = H2O or Cl and H2L is a Schiff base (H2L1,2) or its reduced version ((H3LCl)-Cl-3) derived from pyridoxal, are prepared, as well as two ternary complexes [Cu(L) (phen)] also containing 1,10-phenanthroline. All compounds are characterized by the usual techniques: elemental analyses, ESI mass spectrometry, UV-Vis absorption, FTIR and EPR spectroscopies. The ligands co-ordinate the Cu(II) center forming complexes with square-planar based geometries. Their antioxidant properties are evaluated with a radical scavenging activity assay, with one of the ligand precursors showing activity higher than the positive control, ascorbic acid. The antiproliferative activity of all compounds is evaluated against two cancer cell lines: ovarian (A2780) and breast (MCF7). All complexes show moderate to excellent activity with the ternary Cu-complexes showing IC50 values between 0.7 and 9.3 mu M after 24 h of incubation, values much lower than those reported for cisplatin, the reference drug. The hydrolytic stability of the complexes and their ability to bind albumin and DNA are evaluated by spectroscopic techniques, showing that the compounds bind bovine serum albumin. The [Cu(L)(phen)] complexes show ability to target DNA via intercalation.Fundacao para a Ciencia e Tecnologia (FCT)Portuguese Foundation for Science and TechnologyEuropean Commission [UIDB/00100/2020]FCTPortuguese Foundation for Science and TechnologyEuropean Commission [SFRH/BD/108743/2015

Promotion of phosphoester hydrolysis by the Zr-IV-based metal-organic framework UiO-67

The Zr-IV-based metal-organic framework (MOF) UiO-67 has been examined as a promoter of the hydrolysis of phosphoester bonds by using sodium para-nitrophenylphosphate (pNPP) as a model substrate. The reactions were followed by H-1 NMR spectroscopy and performed under mild conditions using 2-100 mol% of the MOF relative to pNPP. All of the systems studied promoted the hydrolysis of pNPP to give para-nitrophenol (pNPh) and inorganic phosphate. A reaction half-life of ca. 30 min was achieved using 17 mol% of UiO-67 at 55 degrees C and 30 mol% at ambient temperature; >= 98% removal of pNPP was reached within 1 h for both reaction temperatures. H-1 NMR spectra of the reaction solutions, together with powder X-ray diffraction, FT-IR spectroscopy and solid-state NMR data for the recovered MOF, revealed that (i) pNPP was encapsulated and then converted to pNPh within the cavities of UiO-67, (ii) both pNPh and inorganic phosphate were retained in the solid promoter, and (iii) the MOF suffered partial structural breakdown into the components Zr6O4(OH)(4) and 4,4'-biphenyldicarboxylate, with partial release of the latter into solution. These structural changes eventually compromized the recyclability of the promoter, although the material could be recovered and reused in a second cycle without loss of activity. (C) 2015 Elsevier Inc. All rights reserved

Promotion of phosphoester hydrolysis by MoO2Cl2L (L bipyridine derivatives, H2O, no ligand), MoO2(CH3)(2)L (L bipyridine derivatives) and related inorganice-organic hybrids in aqueous media

The compounds MoO2Cl2L (L = 2,2'-bipyridine (bipy) (1); 4,4'-di-tert-butyl-2,2'-bipyridine (di-Bu-t-bipy) (2)), [MoO2Cl2(H2O)(2)]center dot(diglyme)(2) (3), MoO2Cl2 (4), MoO2(CH3)(2)L (L bipy (5); di-Bu-t-bipy (6)), [MoO3(bipy)] n (7), {[MoO3(bipy)][MoO3(H2O)]} n (8), [Mo8O22(OH)(4)(di-Bu-t-bipy)(4)] (9) and MoO3 (10) were tested as phosphoester bond hydrolysis promoters in aqueous media. Sodium para-nitrophenylphosphate (pNPP) was used as a model substrate for the phosphoester bond hydrolysis reaction, which was performed at 55 degrees C, using D2O as solvent and 100 or 10 mol% of the chosen promoter. The progression of all the reactions was monitored by H-1 NMR spectroscopy. All studied systems promote phosphoester bond hydrolysis. The best performance was obtained with MoO2Cl2L compounds (1-4) and with the inorganiceorganic hybrid {[MoO3(bipy)][MoO3(H2O)]}(n) (8). The studied compounds originate either homogeneous or solid/liquid biphasic systems. For the biphasic systems (1, 2, 5-9), the solid phase was recovered at the end of the reaction and characterized by FT-IR spectroscopy. (C) 2014 Elsevier B. V. All rights reserved

Therapeutic potential of vanadium complexes with 1,10-phenanthroline ligands, quo vadis? Fate of complexes in cell media and cancer cells

(VO)-O-IV-complexes formulated as [(VO)-O-IV(OSO3)(phen)(2)] (1) (phen = 1,10-phenanthroline), [(VO)-O-IV(OSO3) (Me(2)phen)(2)] (2) (Me(2)phen = 4,7-dimethyl-1,10-phenanthroline) and [(VO)-O-IV(OSO3)(amphen)(2)] (3) (amphen = 5-amino-1,10-phenanthroline) were prepared and stability in cell incubation media evaluated. Their cytotoxicity was determined against the A2780 (ovarian), MCF7 (breast) and PC3 (prostate) human cancer cells at different incubation times. While at 3 and 24 h the cytotoxicity differs for complexes and corresponding free ligands, at 72 h incubation all compounds are equally active presenting low IC50 values. Upon incubation of A2780 cells with 1-3, cellular distribution of vanadium in cytosol, membranes, nucleus and cytoskeleton, indicate that the uptake of V is low, particularly for 1, and that the uptake pattern depends on the ligand. Nuclear microscopic techniques are used for imaging and elemental quantification in whole PC3 cells incubated with 1. Once complexes are added to cell culture media, they decompose, and with time most V-IV oxidizes to V-V-species. Modeling of speciation when [(VO)-O-IV(OSO3)(phen)(2)] (1) is added to cell media is presented. At lower concentrations of 1, (VO)-O-IV- and phen-containing species are mainly bound to bovine serum albumin, while at higher concentrations [(VO)-O-IV (phen)n](2+)-complexes become relevant, being predicted that the species taken up and mechanisms of action operating depend on the total concentration of complex. This study emphasizes that for these (VO)-O-IV-systems, and probably for many others involving oxidovanadium or other labile metal complexes, it is not possible to identify active species or propose mechanisms of cytotoxic action without evaluating speciation occurring in cell media.Centro de Quimica Estrutural; Centro de Quimica Estrutural - Fundacao para a Ciencia e Tecnologia (FCT) [UID/BIO/04565/2020, UIDB/00100/2020, UID/Multi/04349/2019]; Centro de Ciencias e Tecnologias Nucleares - Fundacao para a Ciencia e Tecnologia (FCT) [UID/BIO/04565/2020, UIDB/00100/2020, UID/Multi/04349/2019]; Programa Operacional Regional de Lisboa 2020 [007317]; FCTPortuguese Foundation for Science and TechnologyEuropean Commission [IF/00841/2012