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Papers by Rodolfo Nieto Vazquez
Journal of Molecular Catalysis B-enzymatic, 2001
Three new cysteine peptidases (araujiain h-I, araujiain h-II and araujiain h-III) were isolated a... more Three new cysteine peptidases (araujiain h-I, araujiain h-II and araujiain h-III) were isolated and purified to mass spectroscopy homogeneity from the latex of Araujia hortorum (Asclepiadaceae) fruits by ultracentrifugation and ion exchange chromatography. The enzymes have molecular masses of 24,030.87, 23,718 and 23,545.5 (mass spectrometry), respectively. The peptidases were activated by thiol compounds and inhibited by common thiol blocking reagents, particularly E-64 and HgCl 2 , suggesting that the enzymes belong to the cysteine peptidases family. A quantitative structure-activity relationship study of their esterolytic activities was performed by means of partial least-squares regression and using the novel filtering technique called orthogonal signal correction. The numerical characterization of the variation in the physicochemical features of the N-α-carbobenzoxy-aminoacid-p-nitrophenyl esters used in the PLS regression modeling was accomplished by using a large number of descriptors extracted from the literature, based on various lipophilicity, polarity and steric scales of the amino acid side-chains in combination with a set of property descriptors derived from semiempirical calculations. From the obtained results it can be concluded that all hydrophobic, electronic, and steric factors are important in the esterase activity of the cysteine peptidases studied.
Journal of Chemical Information and Modeling, 2003
The chromatographic capacity factors (log k′) for 32 structurally diverse drugs were determined b... more The chromatographic capacity factors (log k′) for 32 structurally diverse drugs were determined by high performance liquid chromatography (HPLC) on a stationary phase composed of phospholipids, the socalled immobilized artificial membrane (IAM). In addition, quantitative structure-retention relationships (QSRR) were developed in order to explain the dependence of retention on the chemical structure of the neutral, acidic, and basic drugs considered in this study. The obtained retention data were modeled by means of multiple regression analysis (MLR) and partial least squares (PLS) techniques. The structures of the compounds under study were characterized by means of calculated physicochemical properties and several nonempirical descriptors. For the carboxylic compounds included in the analysis, the obtained results suggest that the IAM-retention is governed by hydrophobicity factors followed by electronic effects due to polarizability in second place. Further, from the analysis of the results obtained of two developed quantitative structure-permeability studies for 20 miscellaneous carboxylic compounds, it may be concluded that the balance between polarizability and hydrophobic effects is not the same toward IAM phases and biological membranes. These results suggest that the IAM phases could not be a suitable model in assessing the acidmembrane interactions. However, it is not possible to generalize this observation, and further work in this area needs to be done to obtain a full understanding of the partitioning of carboxylic compounds in biological membranes. For the non-carboxylic compounds included in the analysis, this work shows that the hydrophobic factors are of prime importance for the IAM-retention of these compounds, while the specific polar interactions, such as electron pair donor-acceptor interactions and electrostatic interactions, are also involved, but they are not dominant.
Microporous and Mesoporous Materials, 2001
This paper presents a theoretical and experimental study of the hybrid sources capabilities to im... more This paper presents a theoretical and experimental study of the hybrid sources capabilities to improve both the dynamic response and the stability of switching power supplies. The hybrid sources are composed by the parallel connection of a linear source and a switching one. The reached improvements are possible without affecting, significantly, the efficiency of the whole circuit. This solution is checked in low voltage sources. The obtained experimental results show these power supplies present high dynamical performance, and therefore they can be used to feed DSPs and microprocessors
Journal of Molecular Structure-theochem, 1998
The optimized geometries and relative energies obtained by four force field and two semi-empirica... more The optimized geometries and relative energies obtained by four force field and two semi-empirical methods were compared with ab initio results computed for formyl-l-alaninamide. Not all methods yielded the same number of minimum energy conformers. Furthermore, while the optimized geometries of the conformers found were comparable, the computed relative energies varied substantially. Also, the force field calculations produced Ramachandran maps that did not even have the appearance of the ab initio Ramachandran map.
En Freud desde 1920 La Repetición incumbe a la Wiederholungzwang, compulsión a la repetición, (tr... more En Freud desde 1920 La Repetición incumbe a la Wiederholungzwang, compulsión a la repetición, (traumática para el sujeto, injustificada en el principio del placer.). Lo expone una importante discusión sobre Compulsión a la Repetición (Wiederholungszwang) en "Más Allá Del Principio De Placer", (1920g), (además de la Pulsión de Muerte), una compulsión básica a repetir. La presenta como una explicación de determinados hechos clínicos: la tendencia a exponerse una y otra vez a situaciones angustiantes. Es un Principio Básico del Psicoanálisis: una persona se ve condenada a repetir algo cuando ha olvidado los orígenes de la pulsión, (y que la cura psicoanalítica puede romper el ciclo de las repeticiones ayudando al paciente.) En la obra de J. Lacan y antes a 1950, el concepto de repetición aparece vinculado al de COMPLEJO, una estructura social internalizada que el sujeto se vuelve a escenificar repetida y compulsivamente. En esa época Lacan traduce el término Wiederholungszwang -empleado por Freudcomo automatisme de repetition, una expresión tomada de las psiquiatría francesa (Pierre Janet, Gaëtan Gaitan de Clérambault.)
Journal of Molecular Catalysis B-enzymatic, 2001
Three new cysteine peptidases (araujiain h-I, araujiain h-II and araujiain h-III) were isolated a... more Three new cysteine peptidases (araujiain h-I, araujiain h-II and araujiain h-III) were isolated and purified to mass spectroscopy homogeneity from the latex of Araujia hortorum (Asclepiadaceae) fruits by ultracentrifugation and ion exchange chromatography. The enzymes have molecular masses of 24,030.87, 23,718 and 23,545.5 (mass spectrometry), respectively. The peptidases were activated by thiol compounds and inhibited by common thiol blocking reagents, particularly E-64 and HgCl 2 , suggesting that the enzymes belong to the cysteine peptidases family. A quantitative structure-activity relationship study of their esterolytic activities was performed by means of partial least-squares regression and using the novel filtering technique called orthogonal signal correction. The numerical characterization of the variation in the physicochemical features of the N-α-carbobenzoxy-aminoacid-p-nitrophenyl esters used in the PLS regression modeling was accomplished by using a large number of descriptors extracted from the literature, based on various lipophilicity, polarity and steric scales of the amino acid side-chains in combination with a set of property descriptors derived from semiempirical calculations. From the obtained results it can be concluded that all hydrophobic, electronic, and steric factors are important in the esterase activity of the cysteine peptidases studied.
Journal of Chemical Information and Modeling, 2003
The chromatographic capacity factors (log k′) for 32 structurally diverse drugs were determined b... more The chromatographic capacity factors (log k′) for 32 structurally diverse drugs were determined by high performance liquid chromatography (HPLC) on a stationary phase composed of phospholipids, the socalled immobilized artificial membrane (IAM). In addition, quantitative structure-retention relationships (QSRR) were developed in order to explain the dependence of retention on the chemical structure of the neutral, acidic, and basic drugs considered in this study. The obtained retention data were modeled by means of multiple regression analysis (MLR) and partial least squares (PLS) techniques. The structures of the compounds under study were characterized by means of calculated physicochemical properties and several nonempirical descriptors. For the carboxylic compounds included in the analysis, the obtained results suggest that the IAM-retention is governed by hydrophobicity factors followed by electronic effects due to polarizability in second place. Further, from the analysis of the results obtained of two developed quantitative structure-permeability studies for 20 miscellaneous carboxylic compounds, it may be concluded that the balance between polarizability and hydrophobic effects is not the same toward IAM phases and biological membranes. These results suggest that the IAM phases could not be a suitable model in assessing the acidmembrane interactions. However, it is not possible to generalize this observation, and further work in this area needs to be done to obtain a full understanding of the partitioning of carboxylic compounds in biological membranes. For the non-carboxylic compounds included in the analysis, this work shows that the hydrophobic factors are of prime importance for the IAM-retention of these compounds, while the specific polar interactions, such as electron pair donor-acceptor interactions and electrostatic interactions, are also involved, but they are not dominant.
Microporous and Mesoporous Materials, 2001
This paper presents a theoretical and experimental study of the hybrid sources capabilities to im... more This paper presents a theoretical and experimental study of the hybrid sources capabilities to improve both the dynamic response and the stability of switching power supplies. The hybrid sources are composed by the parallel connection of a linear source and a switching one. The reached improvements are possible without affecting, significantly, the efficiency of the whole circuit. This solution is checked in low voltage sources. The obtained experimental results show these power supplies present high dynamical performance, and therefore they can be used to feed DSPs and microprocessors
Journal of Molecular Structure-theochem, 1998
The optimized geometries and relative energies obtained by four force field and two semi-empirica... more The optimized geometries and relative energies obtained by four force field and two semi-empirical methods were compared with ab initio results computed for formyl-l-alaninamide. Not all methods yielded the same number of minimum energy conformers. Furthermore, while the optimized geometries of the conformers found were comparable, the computed relative energies varied substantially. Also, the force field calculations produced Ramachandran maps that did not even have the appearance of the ab initio Ramachandran map.
En Freud desde 1920 La Repetición incumbe a la Wiederholungzwang, compulsión a la repetición, (tr... more En Freud desde 1920 La Repetición incumbe a la Wiederholungzwang, compulsión a la repetición, (traumática para el sujeto, injustificada en el principio del placer.). Lo expone una importante discusión sobre Compulsión a la Repetición (Wiederholungszwang) en "Más Allá Del Principio De Placer", (1920g), (además de la Pulsión de Muerte), una compulsión básica a repetir. La presenta como una explicación de determinados hechos clínicos: la tendencia a exponerse una y otra vez a situaciones angustiantes. Es un Principio Básico del Psicoanálisis: una persona se ve condenada a repetir algo cuando ha olvidado los orígenes de la pulsión, (y que la cura psicoanalítica puede romper el ciclo de las repeticiones ayudando al paciente.) En la obra de J. Lacan y antes a 1950, el concepto de repetición aparece vinculado al de COMPLEJO, una estructura social internalizada que el sujeto se vuelve a escenificar repetida y compulsivamente. En esa época Lacan traduce el término Wiederholungszwang -empleado por Freudcomo automatisme de repetition, una expresión tomada de las psiquiatría francesa (Pierre Janet, Gaëtan Gaitan de Clérambault.)