Carla Cruz - Academia.edu (original) (raw)
Papers by Carla Cruz
Organic & Biomolecular Chemistry, 2004
The 28-membered octaazamacrocycle Me2[28]py2N6 was used as a receptor for the molecular recogniti... more The 28-membered octaazamacrocycle Me2[28]py2N6 was used as a receptor for the molecular recognition of aromatic and aliphatic carboxylate substrates. The receptor-substrate binding behaviour of (H6Me2[28]py2N6)6+ with an aliphatic (-O2C(CH2)nCO2-, n=0 to 4) and an aromatic (phthalate, isophthalate, terephthalate, 4,4'-dibenzoate, benzoate, 3- and 4-nitrobenzoate) series of carboxylate anions was evaluated by 1H NMR spectroscopy (carried out in DMSO-d6 at 300 K). Two association constants were found for most of the studied cases, except for 3- and 4-nitrobenzoate for which only K1 was determined. For oxalate, malonate, benzoate and dibenzoate anions only the beta2 constants could be obtained. The values of the first association constant cover a range from 2.86 to 3.69 (log units), and the second stepwise constant from 2.15 to 2.89 (also in log units). No special selectivity was found but the highest values were determined for adipate and the lowest for the monoprotic 3- and 4-nitrobenzoates. Single crystal X-ray structures of H6Me2[28]py2N6 6+ with terephthalate, 1, and 4,4'-dibenzoate (2) were determined showing supramolecular entities with general formula (H6Me2[28]py2N6).(substrate)2(PF6)2.4H2O. These anions are the building blocks of an extensive 3-D network of hydrogen bonds.
Dalton Transactions, 2003
Carla Cruz,a Sílvia Carvalho,b Rita Delgado,b,c Michael GB Drew,d Vítor Félixa and Brian J. Goodf... more Carla Cruz,a Sílvia Carvalho,b Rita Delgado,b,c Michael GB Drew,d Vítor Félixa and Brian J. Goodfellowa a Departamento Química, CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal b Instituto de Tecnologia Química e Biológica, UNL, Apartado 127, 2781-901 ...
Dalton Transactions, 2003
The hexaazamacrocycle 7,22-dimethyl-3,7,11,18,22,26-hexaazatricyclo[26.2.2.2 13,16 ]tetratriacont... more The hexaazamacrocycle 7,22-dimethyl-3,7,11,18,22,26-hexaazatricyclo[26.2.2.2 13,16 ]tetratriaconta-1(30),13,15,28,31,33-hexaene (Me 2 [30]pbz 2 N 6 ) was synthesized and characterised by single crystal X-ray diffraction. The macrocycle adopts a conformation with the two ...
PLoS ONE, 2011
Background: Useful probes of the intracellular environment that target a specific organelle in or... more Background: Useful probes of the intracellular environment that target a specific organelle in order to allow direct observation of the changes in these regions is of high current interest. Macrocyclic ligands have already revealed themselves as important selective hosts in some biological applications, forming stable and specific complexes. Therefore, in this paper, several macrocyclic ligands are evaluated as potential molecular probes.
Journal of Molecular Recognition, 2014
The present study explores the effect of oligonucleotide composition on the mechanism of retentio... more The present study explores the effect of oligonucleotide composition on the mechanism of retention to l-methionine agarose support by chromatography and saturation transfer difference (STD)-nuclear magnetic resonance (NMR) techniques. All chromatographic experiments were performed using 1.5 M (NH4 )2 SO4 . The binding profiles obtained by chromatography show that oligonucleotides with thymine had the highest retention time. In general, the larger homo-oligonucleotides are more retained to the l-methionine agarose support. Moreover, the study with hetero-oligonucleotides confirms that the presence of guanine reduces the retention on the l-methionine chromatographic support. These results are in accord with STD-NMR experiments, which show that the strongest signals were observed for the methyl group of thymine, and no STD signals were observed for the guanosine protons. Finally, the retention behaviour of linear plasmid DNA (pDNA) with different sizes and base composition (2.7-kbp pUC19, 6.05-kbp pVAX1-LacZ, 7.4-kbp pVAX1-LacZgag and 14-kbp pcDNA-based plasmid) was also evaluated by chromatography. The results indicate that the underlying mechanism of retention involves not only hydrophobic interactions but also other elementary interactions responsible for the biorecognition of pDNA molecules by l-methionine ligands. Copyright © 2014 John Wiley & Sons, Ltd.
Organic & Biomolecular Chemistry, 2004
The 28-membered octaazamacrocycle Me2[28]py2N6 was used as a receptor for the molecular recogniti... more The 28-membered octaazamacrocycle Me2[28]py2N6 was used as a receptor for the molecular recognition of aromatic and aliphatic carboxylate substrates. The receptor-substrate binding behaviour of (H6Me2[28]py2N6)6+ with an aliphatic (-O2C(CH2)nCO2-, n=0 to 4) and an aromatic (phthalate, isophthalate, terephthalate, 4,4'-dibenzoate, benzoate, 3- and 4-nitrobenzoate) series of carboxylate anions was evaluated by 1H NMR spectroscopy (carried out in DMSO-d6 at 300 K). Two association constants were found for most of the studied cases, except for 3- and 4-nitrobenzoate for which only K1 was determined. For oxalate, malonate, benzoate and dibenzoate anions only the beta2 constants could be obtained. The values of the first association constant cover a range from 2.86 to 3.69 (log units), and the second stepwise constant from 2.15 to 2.89 (also in log units). No special selectivity was found but the highest values were determined for adipate and the lowest for the monoprotic 3- and 4-nitrobenzoates. Single crystal X-ray structures of H6Me2[28]py2N6 6+ with terephthalate, 1, and 4,4'-dibenzoate (2) were determined showing supramolecular entities with general formula (H6Me2[28]py2N6).(substrate)2(PF6)2.4H2O. These anions are the building blocks of an extensive 3-D network of hydrogen bonds.
The Journal of Organic Chemistry, 2007
The novel dioxatetraaza macrocycle [26]phen 2 N 4 O 2 , which incorporates two phenanthroline uni... more The novel dioxatetraaza macrocycle [26]phen 2 N 4 O 2 , which incorporates two phenanthroline units, has been synthesized, and its acid-base behavior has been evaluated by potentiometric and 1 H NMR methods. Six protonation constants were determined, and the protonation sequence was established by NMR. The location of the fifth proton on the phen nitrogen was confirmed by X-ray determinations of the crystal structures of the receptor as bromide and chloride salts. The two compounds have the general molecular formula {(H 5 [26]phen 2 N 4 O 2 )X n (H 2 O) 5-n }X n-1 ‚mH 2 O, where X ) Cl, n ) 3, and m ) 6 or X ) Br, n ) 4, and m ) 5.5. In the solid state, the (H 5 [26]phen 2 N 4 O 2 ) 5+ cation adopts a "horseshoe" topology with sufficient room to encapsulate three or four halogen anions through the several N-H‚‚‚X hydrogenbonding interactions. Two supermolecules {(H 5 [26]phen 2 N 4 O 2 )X n (H 2 O) 5-n } (5-n)+ form an interpenetrating dimeric species, which was also found by ESI mass spectrum. Binding studies of the protonated macrocycle with aliphatic (ox 2-, mal 2-, suc 2-, cit 3-, cta 3-) and aromatic (bzc -, naphc -, anthc -, pyrc -, ph 2-, iph 2-, tph 2-, btc 3-) anions were determined in water by potentiometric methods. These studies were complemented by 1 H NMR titrations in D 2 O of the receptor with selected anions. The H i [26]phen 2 N 4 O 2 i+ receptor can selectively uptake highly charged or extended aromatic carboxylate anions, such as btc 3and pyrc -, in the pH ranges of 4.0-8.5 and <4.0, respectively, from aqueous solution that contain the remaining anions as pollutants or contaminants. To obtain further insight into these structural and experimental findings, molecular dynamics (MD) simulations were carried out in water solution. (1) (a) Supramolecular Chemistry of Anions; Bianchi, A.; Bowman-James, K.; García-España, E., Eds.; Wiley-VCH: New York, 1997. (b) Amendola, V.; Bonizzoni, M.; Esteban-Gómez, D.; Fabbrizzi, L.; Licchelli, M.; Sancenón, F.; Taglietti, A. (4) (a) García-España, E.; Díaz, P.; Llinares, J. M.; Clares, M. P.; Bianchi, A.
Journal of Chromatography A, 2011
The epitope mapping of nucleotides bound to three chromatography supports is accomplished using s... more The epitope mapping of nucleotides bound to three chromatography supports is accomplished using saturation transfer difference (STD)-NMR spectroscopy. This experiment involves subtracting a spectrum in which the support was selectively saturated from one recorded without support saturation. In the difference spectrum only the signals of the ligands that bind to the support and received saturation transfer remain. The nucleotide protons in closer contact with the support have more intense signals due to a more efficient transfer of saturation. We investigate the effects on the binding to the nucleotides by the introduction of a spacer arm between l-histidine and Sepharose. Our NMR experiments evidence a clear contribution of the spacer to the interaction with all the nucleotides, increasing the mobility of the amino acid and giving different STD responses. This enhanced mobility originates the reinforcement of the interactions with the sugar moiety and phosphate group of 5 -CMP and 5 -TMP or the base of 5 -GMP and 5 -UMP. Hence, with this study we show that by using STD NMR technique on chromatographic systems it is possible to provide a fast, robust and efficient way of screening the atoms involved in the binding to the supports.
Forest Ecology and Management, 2005
The alliance between remote sensing techniques and biophysical indicators can be valuable to stud... more The alliance between remote sensing techniques and biophysical indicators can be valuable to studies on diagnosis and monitoring, especially in threatened habitats, such as the Atlantic Rainforest. This approach may improve monitoring through diagnosing forest fragments instead of quantifying only forest area reduction. This paper aims to evaluate relationships between forest structure and vegetation indices in Atlantic Rainforest fragments, in southeastern Brazil. Two Landsat 7 ETM+ images acquired in humid and dry seasons were used, and measurements of forest structure in nine forest fragments and in a continuous forest area in the Guapiaçú River Basin, in Rio de Janeiro State were taken. Three vegetation indices (normalized difference vegetation index (NDVI), moisture vegetation index using Landsat's band 5 (MVI5) and moisture vegetation index using Landsat's band 7 (MVI7)) were correlated with measurements of forest structure (frequency of multiple-stemmed trees, density of trees, mean and range of tree diameter, mean and range of tree height and average of basal area). Models describing the relationships between forest structure and vegetation indices using linear regression analysis were also developed. MVI5 and MVI7 showed the best performances in dense humid forests, whereas NDVI seems to be a good indicator of green biomass in deciduous and dry forests. Moreover, the saturation matter in vegetation indices and the transferability of relationships between biophysical characteristics and vegetation indices to other sites and times were discussed. #
FEMS Microbiology Letters, 2005
In mycobacteria, the study of inhibition by metal ions has been limited by the absence of suitabl... more In mycobacteria, the study of inhibition by metal ions has been limited by the absence of suitable molecular vectors. Recently, we reported on the inhibitory activity of a family of chelators, macrocyclic compounds (MCC), against Mycobacterium tuberculosis. In this study equimolar concentrations of the free cations vanadium(IV), arsenic(III), iron(III), indium(III) and bismuth(III), and as 1:1 complexes with the MCC 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetra-acetic acid (TETA) were tested in vitro against M. tuberculosis using the Bactece 460 TB radiometric technology (Becton-Dickinson, MD, USA). Radiometric inhibition above 80% was obtained with free indium(III) and bismuth(III), and ranged from 80% to 99%, with the complexes of TETA with vanadium(IV), bismuth(III) and indium(III), in the order of increasing activity. The highest radiometric inhibition levels were obtained with the [In(TETA)] À complex, which caused drops of up to 4 log units in cellular viability. The minimal inhibitory concentration of this compound was evaluated at 3 lM.
Dalton Transactions, 2003
Carla Cruz,a Sílvia Carvalho,b Rita Delgado,b,c Michael GB Drew,d Vítor Félixa and Brian J. Goodf... more Carla Cruz,a Sílvia Carvalho,b Rita Delgado,b,c Michael GB Drew,d Vítor Félixa and Brian J. Goodfellowa a Departamento Química, CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal b Instituto de Tecnologia Química e Biológica, UNL, Apartado 127, 2781-901 ...
Chemistry - A European Journal, 2009
Analytical Chemistry, 2013
Minicircle DNA (mcDNA) is recently becoming an exciting source of genetic material for therapeuti... more Minicircle DNA (mcDNA) is recently becoming an exciting source of genetic material for therapeutic purposes due to its exceptional biocompatibility and efficiency over typical DNA. However, its widespread use is yet restrained because of the absence of an efficient technology that allows its purification. Here, the precise conditions of mcDNA interaction with novel arginine-arginine dipeptide ligands were explored to promote binding and recovery of these biopharmaceuticals. Such interactions were investigated by taking advantage of a highly sensitive method based on surface plasmon resonance (SPR) to screen, in real-time, for ligand-coupled biomolecules, while preserving mcDNA integrity. Through this analytic approach, we detected dynamic binding responses that are dependent on buffer type, mcDNA electrokinetic potential, and temperature conditions. Remarkably, the results obtained revealed that the ligands possess high affinity to mcDNA molecules under low salt buffers, and low affinity in the presence of salt, suggesting that electrostatic interactions mainly govern ligand-analyte coupling. These findings provide important insights for an active manipulation of parameters that promote mcDNA recovery and purification. Above all, this study showed the crucial importance of SPR for future screening of other ligands that, like the one described herein, can be used to design mcDNA recovery platforms which will have significant impact in biopharmaceutical-based therapeutics.
Analytical and Bioanalytical Chemistry, 2011
Here, we describe a rapid and efficient screening method using surface plasmon resonance (SPR) an... more Here, we describe a rapid and efficient screening method using surface plasmon resonance (SPR) and saturation transfer difference-nuclear magnetic resonance (STD-NMR) spectroscopy to yield information regarding the residues involved in nucleotide binding to amino acidcoated supports. The aim of this work was to explore the use of these spectroscopic techniques to study amino acidnucleotide interactions in order to improve the binding specificity of the amino acid ligands used to purify plasmid DNA. For SPR, we present a strategy that immobilizes arginine and lysine on a surface as model supports, and we analyze binding responses when synthetic homodeoxyoligonucleotides are injected over the amino acid surface. The binding responses are detectable and reproducible despite the small size of the immobilized amino acids. Using STD-NMR, we performed epitope mapping of homodeoxyoligonucleotides bound to L-arginine-bisoxyran-Sepharose and L-lysine-Sepharose supports. Polynucleotide binding preferences differed; for example, polyC interacted preferentially through its backbone with the two supports, whereas polyT bound the supports through its thymine moiety. STD-NMR combined with SPR measurements was successfully used to screen amino acid-nucleotide interactions and determine the binding affinities of the complexes.
Organic & Biomolecular Chemistry, 2004
The 28-membered octaazamacrocycle Me2[28]py2N6 was used as a receptor for the molecular recogniti... more The 28-membered octaazamacrocycle Me2[28]py2N6 was used as a receptor for the molecular recognition of aromatic and aliphatic carboxylate substrates. The receptor-substrate binding behaviour of (H6Me2[28]py2N6)6+ with an aliphatic (-O2C(CH2)nCO2-, n=0 to 4) and an aromatic (phthalate, isophthalate, terephthalate, 4,4&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-dibenzoate, benzoate, 3- and 4-nitrobenzoate) series of carboxylate anions was evaluated by 1H NMR spectroscopy (carried out in DMSO-d6 at 300 K). Two association constants were found for most of the studied cases, except for 3- and 4-nitrobenzoate for which only K1 was determined. For oxalate, malonate, benzoate and dibenzoate anions only the beta2 constants could be obtained. The values of the first association constant cover a range from 2.86 to 3.69 (log units), and the second stepwise constant from 2.15 to 2.89 (also in log units). No special selectivity was found but the highest values were determined for adipate and the lowest for the monoprotic 3- and 4-nitrobenzoates. Single crystal X-ray structures of H6Me2[28]py2N6 6+ with terephthalate, 1, and 4,4&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-dibenzoate (2) were determined showing supramolecular entities with general formula (H6Me2[28]py2N6).(substrate)2(PF6)2.4H2O. These anions are the building blocks of an extensive 3-D network of hydrogen bonds.
Dalton Transactions, 2003
Carla Cruz,a Sílvia Carvalho,b Rita Delgado,b,c Michael GB Drew,d Vítor Félixa and Brian J. Goodf... more Carla Cruz,a Sílvia Carvalho,b Rita Delgado,b,c Michael GB Drew,d Vítor Félixa and Brian J. Goodfellowa a Departamento Química, CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal b Instituto de Tecnologia Química e Biológica, UNL, Apartado 127, 2781-901 ...
Dalton Transactions, 2003
The hexaazamacrocycle 7,22-dimethyl-3,7,11,18,22,26-hexaazatricyclo[26.2.2.2 13,16 ]tetratriacont... more The hexaazamacrocycle 7,22-dimethyl-3,7,11,18,22,26-hexaazatricyclo[26.2.2.2 13,16 ]tetratriaconta-1(30),13,15,28,31,33-hexaene (Me 2 [30]pbz 2 N 6 ) was synthesized and characterised by single crystal X-ray diffraction. The macrocycle adopts a conformation with the two ...
PLoS ONE, 2011
Background: Useful probes of the intracellular environment that target a specific organelle in or... more Background: Useful probes of the intracellular environment that target a specific organelle in order to allow direct observation of the changes in these regions is of high current interest. Macrocyclic ligands have already revealed themselves as important selective hosts in some biological applications, forming stable and specific complexes. Therefore, in this paper, several macrocyclic ligands are evaluated as potential molecular probes.
Journal of Molecular Recognition, 2014
The present study explores the effect of oligonucleotide composition on the mechanism of retentio... more The present study explores the effect of oligonucleotide composition on the mechanism of retention to l-methionine agarose support by chromatography and saturation transfer difference (STD)-nuclear magnetic resonance (NMR) techniques. All chromatographic experiments were performed using 1.5 M (NH4 )2 SO4 . The binding profiles obtained by chromatography show that oligonucleotides with thymine had the highest retention time. In general, the larger homo-oligonucleotides are more retained to the l-methionine agarose support. Moreover, the study with hetero-oligonucleotides confirms that the presence of guanine reduces the retention on the l-methionine chromatographic support. These results are in accord with STD-NMR experiments, which show that the strongest signals were observed for the methyl group of thymine, and no STD signals were observed for the guanosine protons. Finally, the retention behaviour of linear plasmid DNA (pDNA) with different sizes and base composition (2.7-kbp pUC19, 6.05-kbp pVAX1-LacZ, 7.4-kbp pVAX1-LacZgag and 14-kbp pcDNA-based plasmid) was also evaluated by chromatography. The results indicate that the underlying mechanism of retention involves not only hydrophobic interactions but also other elementary interactions responsible for the biorecognition of pDNA molecules by l-methionine ligands. Copyright © 2014 John Wiley &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Sons, Ltd.
Organic & Biomolecular Chemistry, 2004
The 28-membered octaazamacrocycle Me2[28]py2N6 was used as a receptor for the molecular recogniti... more The 28-membered octaazamacrocycle Me2[28]py2N6 was used as a receptor for the molecular recognition of aromatic and aliphatic carboxylate substrates. The receptor-substrate binding behaviour of (H6Me2[28]py2N6)6+ with an aliphatic (-O2C(CH2)nCO2-, n=0 to 4) and an aromatic (phthalate, isophthalate, terephthalate, 4,4&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-dibenzoate, benzoate, 3- and 4-nitrobenzoate) series of carboxylate anions was evaluated by 1H NMR spectroscopy (carried out in DMSO-d6 at 300 K). Two association constants were found for most of the studied cases, except for 3- and 4-nitrobenzoate for which only K1 was determined. For oxalate, malonate, benzoate and dibenzoate anions only the beta2 constants could be obtained. The values of the first association constant cover a range from 2.86 to 3.69 (log units), and the second stepwise constant from 2.15 to 2.89 (also in log units). No special selectivity was found but the highest values were determined for adipate and the lowest for the monoprotic 3- and 4-nitrobenzoates. Single crystal X-ray structures of H6Me2[28]py2N6 6+ with terephthalate, 1, and 4,4&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-dibenzoate (2) were determined showing supramolecular entities with general formula (H6Me2[28]py2N6).(substrate)2(PF6)2.4H2O. These anions are the building blocks of an extensive 3-D network of hydrogen bonds.
The Journal of Organic Chemistry, 2007
The novel dioxatetraaza macrocycle [26]phen 2 N 4 O 2 , which incorporates two phenanthroline uni... more The novel dioxatetraaza macrocycle [26]phen 2 N 4 O 2 , which incorporates two phenanthroline units, has been synthesized, and its acid-base behavior has been evaluated by potentiometric and 1 H NMR methods. Six protonation constants were determined, and the protonation sequence was established by NMR. The location of the fifth proton on the phen nitrogen was confirmed by X-ray determinations of the crystal structures of the receptor as bromide and chloride salts. The two compounds have the general molecular formula {(H 5 [26]phen 2 N 4 O 2 )X n (H 2 O) 5-n }X n-1 ‚mH 2 O, where X ) Cl, n ) 3, and m ) 6 or X ) Br, n ) 4, and m ) 5.5. In the solid state, the (H 5 [26]phen 2 N 4 O 2 ) 5+ cation adopts a "horseshoe" topology with sufficient room to encapsulate three or four halogen anions through the several N-H‚‚‚X hydrogenbonding interactions. Two supermolecules {(H 5 [26]phen 2 N 4 O 2 )X n (H 2 O) 5-n } (5-n)+ form an interpenetrating dimeric species, which was also found by ESI mass spectrum. Binding studies of the protonated macrocycle with aliphatic (ox 2-, mal 2-, suc 2-, cit 3-, cta 3-) and aromatic (bzc -, naphc -, anthc -, pyrc -, ph 2-, iph 2-, tph 2-, btc 3-) anions were determined in water by potentiometric methods. These studies were complemented by 1 H NMR titrations in D 2 O of the receptor with selected anions. The H i [26]phen 2 N 4 O 2 i+ receptor can selectively uptake highly charged or extended aromatic carboxylate anions, such as btc 3and pyrc -, in the pH ranges of 4.0-8.5 and <4.0, respectively, from aqueous solution that contain the remaining anions as pollutants or contaminants. To obtain further insight into these structural and experimental findings, molecular dynamics (MD) simulations were carried out in water solution. (1) (a) Supramolecular Chemistry of Anions; Bianchi, A.; Bowman-James, K.; García-España, E., Eds.; Wiley-VCH: New York, 1997. (b) Amendola, V.; Bonizzoni, M.; Esteban-Gómez, D.; Fabbrizzi, L.; Licchelli, M.; Sancenón, F.; Taglietti, A. (4) (a) García-España, E.; Díaz, P.; Llinares, J. M.; Clares, M. P.; Bianchi, A.
Journal of Chromatography A, 2011
The epitope mapping of nucleotides bound to three chromatography supports is accomplished using s... more The epitope mapping of nucleotides bound to three chromatography supports is accomplished using saturation transfer difference (STD)-NMR spectroscopy. This experiment involves subtracting a spectrum in which the support was selectively saturated from one recorded without support saturation. In the difference spectrum only the signals of the ligands that bind to the support and received saturation transfer remain. The nucleotide protons in closer contact with the support have more intense signals due to a more efficient transfer of saturation. We investigate the effects on the binding to the nucleotides by the introduction of a spacer arm between l-histidine and Sepharose. Our NMR experiments evidence a clear contribution of the spacer to the interaction with all the nucleotides, increasing the mobility of the amino acid and giving different STD responses. This enhanced mobility originates the reinforcement of the interactions with the sugar moiety and phosphate group of 5 -CMP and 5 -TMP or the base of 5 -GMP and 5 -UMP. Hence, with this study we show that by using STD NMR technique on chromatographic systems it is possible to provide a fast, robust and efficient way of screening the atoms involved in the binding to the supports.
Forest Ecology and Management, 2005
The alliance between remote sensing techniques and biophysical indicators can be valuable to stud... more The alliance between remote sensing techniques and biophysical indicators can be valuable to studies on diagnosis and monitoring, especially in threatened habitats, such as the Atlantic Rainforest. This approach may improve monitoring through diagnosing forest fragments instead of quantifying only forest area reduction. This paper aims to evaluate relationships between forest structure and vegetation indices in Atlantic Rainforest fragments, in southeastern Brazil. Two Landsat 7 ETM+ images acquired in humid and dry seasons were used, and measurements of forest structure in nine forest fragments and in a continuous forest area in the Guapiaçú River Basin, in Rio de Janeiro State were taken. Three vegetation indices (normalized difference vegetation index (NDVI), moisture vegetation index using Landsat's band 5 (MVI5) and moisture vegetation index using Landsat's band 7 (MVI7)) were correlated with measurements of forest structure (frequency of multiple-stemmed trees, density of trees, mean and range of tree diameter, mean and range of tree height and average of basal area). Models describing the relationships between forest structure and vegetation indices using linear regression analysis were also developed. MVI5 and MVI7 showed the best performances in dense humid forests, whereas NDVI seems to be a good indicator of green biomass in deciduous and dry forests. Moreover, the saturation matter in vegetation indices and the transferability of relationships between biophysical characteristics and vegetation indices to other sites and times were discussed. #
FEMS Microbiology Letters, 2005
In mycobacteria, the study of inhibition by metal ions has been limited by the absence of suitabl... more In mycobacteria, the study of inhibition by metal ions has been limited by the absence of suitable molecular vectors. Recently, we reported on the inhibitory activity of a family of chelators, macrocyclic compounds (MCC), against Mycobacterium tuberculosis. In this study equimolar concentrations of the free cations vanadium(IV), arsenic(III), iron(III), indium(III) and bismuth(III), and as 1:1 complexes with the MCC 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetra-acetic acid (TETA) were tested in vitro against M. tuberculosis using the Bactece 460 TB radiometric technology (Becton-Dickinson, MD, USA). Radiometric inhibition above 80% was obtained with free indium(III) and bismuth(III), and ranged from 80% to 99%, with the complexes of TETA with vanadium(IV), bismuth(III) and indium(III), in the order of increasing activity. The highest radiometric inhibition levels were obtained with the [In(TETA)] À complex, which caused drops of up to 4 log units in cellular viability. The minimal inhibitory concentration of this compound was evaluated at 3 lM.
Dalton Transactions, 2003
Carla Cruz,a Sílvia Carvalho,b Rita Delgado,b,c Michael GB Drew,d Vítor Félixa and Brian J. Goodf... more Carla Cruz,a Sílvia Carvalho,b Rita Delgado,b,c Michael GB Drew,d Vítor Félixa and Brian J. Goodfellowa a Departamento Química, CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal b Instituto de Tecnologia Química e Biológica, UNL, Apartado 127, 2781-901 ...
Chemistry - A European Journal, 2009
Analytical Chemistry, 2013
Minicircle DNA (mcDNA) is recently becoming an exciting source of genetic material for therapeuti... more Minicircle DNA (mcDNA) is recently becoming an exciting source of genetic material for therapeutic purposes due to its exceptional biocompatibility and efficiency over typical DNA. However, its widespread use is yet restrained because of the absence of an efficient technology that allows its purification. Here, the precise conditions of mcDNA interaction with novel arginine-arginine dipeptide ligands were explored to promote binding and recovery of these biopharmaceuticals. Such interactions were investigated by taking advantage of a highly sensitive method based on surface plasmon resonance (SPR) to screen, in real-time, for ligand-coupled biomolecules, while preserving mcDNA integrity. Through this analytic approach, we detected dynamic binding responses that are dependent on buffer type, mcDNA electrokinetic potential, and temperature conditions. Remarkably, the results obtained revealed that the ligands possess high affinity to mcDNA molecules under low salt buffers, and low affinity in the presence of salt, suggesting that electrostatic interactions mainly govern ligand-analyte coupling. These findings provide important insights for an active manipulation of parameters that promote mcDNA recovery and purification. Above all, this study showed the crucial importance of SPR for future screening of other ligands that, like the one described herein, can be used to design mcDNA recovery platforms which will have significant impact in biopharmaceutical-based therapeutics.
Analytical and Bioanalytical Chemistry, 2011
Here, we describe a rapid and efficient screening method using surface plasmon resonance (SPR) an... more Here, we describe a rapid and efficient screening method using surface plasmon resonance (SPR) and saturation transfer difference-nuclear magnetic resonance (STD-NMR) spectroscopy to yield information regarding the residues involved in nucleotide binding to amino acidcoated supports. The aim of this work was to explore the use of these spectroscopic techniques to study amino acidnucleotide interactions in order to improve the binding specificity of the amino acid ligands used to purify plasmid DNA. For SPR, we present a strategy that immobilizes arginine and lysine on a surface as model supports, and we analyze binding responses when synthetic homodeoxyoligonucleotides are injected over the amino acid surface. The binding responses are detectable and reproducible despite the small size of the immobilized amino acids. Using STD-NMR, we performed epitope mapping of homodeoxyoligonucleotides bound to L-arginine-bisoxyran-Sepharose and L-lysine-Sepharose supports. Polynucleotide binding preferences differed; for example, polyC interacted preferentially through its backbone with the two supports, whereas polyT bound the supports through its thymine moiety. STD-NMR combined with SPR measurements was successfully used to screen amino acid-nucleotide interactions and determine the binding affinities of the complexes.