GIOVANA GRANADOS | Universidad Distrital Francisco Jose de Caldas, Bogota, Colombia (original) (raw)

Papers by GIOVANA GRANADOS

Applied Microbiology and Biotechnology, 2011

Revista Colombiana de Química, 2021

El parásito intracelular Leishmania braziliensis es el agente causal de la leishmaniasis cutánea,... more El parásito intracelular Leishmania braziliensis es el agente causal de la leishmaniasis cutánea, enfermedad endémica de zonas tropicales, cuyos tratamientos farmacológicos son tóxicos y para la cual no se dispone de una vacuna en la actualidad. Por esta razón, el estudio de las proteínas relacionadas con el metabolismo energético del parásito es relevante dada su importancia para la supervivencia del mismo. En este estudio, utilizando como secuencia plantilla los primeros 18 residuos del extremo N-terminal de la proteína nicotinamida/nicotinato mononucleótido adenilil transferasa de L. braziliensis (Lb-NMNAT), se sintetizaron péptidos implementando la estrategia Fmoc/tert-Butilo en una resina Rink amida MBHA. Los péptidos se purificaron por cromatografía en columna C18 y se caracterizaron mediante RP-HPLC. La proteína recombinante 6xHisLb-NMNAT se expresó en células Escherichia coli M15 y se purificó parcialmente empleando cromatografía de afinidad a metales inmovilizados. De esta ...

Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 2021

La nicotinamida/nicotinato mononucleótido adenililtransferasa (NMNAT, EC 2.7.7.1/18) desempeñauna... more La nicotinamida/nicotinato mononucleótido adenililtransferasa (NMNAT, EC 2.7.7.1/18) desempeñauna función central en la síntesis del dinucleótido de adenina y nicotinamida (NAD) debido a queen esta enzima confluyen las rutas de síntesis de novo y de reciclaje. El NAD es una moléculatrascendental en el metabolismo de todos los seres vivos, principalmente en el metabolismo redox. Eneste estudio se presenta una nueva estrategia metodológica para la evaluación de posibles inhibidoresde la NMNAT de Leishmania braziliensis (LbNMNAT). El método suprime la actividad inhibitoriacruzada con la enzima acoplada al ensayo de detección, la alcohol dehidrogenasa (ADH, EC 1.1.1.1).Experimentalmente se introdujo un paso intermedio de extracción en fase sólida de los inhibidoresantes de la ejecución del sistema enzimático de detección. La implementación del paso de extracciónposibilitó la evaluación específica de la enzima de interés, la LbNMNAT, sin afectar la enzimaacoplada ADH. El nuevo método per...

The Journal of Chemical Physics, 2020

We present a model of circular dichroism for proteins that is based on the classical electromagne... more We present a model of circular dichroism for proteins that is based on the classical electromagnetic theory for optical activity. The two additional constituents of the model are as follows: an appropriate characterization of the secondary structure of the protein residues and the assignment of an effective polarizability to each type of classified residue. The set of effective polarizabilities is obtained by means of a Monte Carlo statistical method, which is used to analyze a series of synchrotron radiation circular dichroism spectra together with their corresponding crystallographic structures. As a result, the predicted spectra from our model are in good accord with experimental data, as well as with the results of some other theoretical approaches.

Biophysical Journal, 2018

Journal of Physics: Conference Series, 2016

Quantum Mechanics is the favourite theory to predict the structure of any group of atoms, includi... more Quantum Mechanics is the favourite theory to predict the structure of any group of atoms, including biological molecules. Due to numerous difficulties, however, it is necessary to introduce a series of approximations to overcome such impediments. We present a coarse-grained model of circular dichroism (CD) that is based on the theory of optical activity, developed by DeVoe, in order to predict CD spectra. In first stage, we determine the polarisability of individual monomers (residues, in the case of peptides) from experiments of molar absorptivity. The complex polarisabilities are used together with peptide structures obtained by density functional theory and other methods to determine their corresponding CD spectra, which are in reasonable agreement with their experimental counterparts.

Vaccine, 2003

It has been demonstrated that Plasmodium falciparum sporozoite threonine-asparagine-rich protein ... more It has been demonstrated that Plasmodium falciparum sporozoite threonine-asparagine-rich protein (PfSTARP) is located on the sporozoite surface. This protein's non-overlapping consecutive peptides were synthesised and tested in Hep G2 cell binding assays. Twelve high activity binding peptides (HABPs) were identified in the resulting 31 peptides. Three were found in 5 non-repeat region (amino acids 41-80). Peptides 20546 (41 VIKHNRFLSEYQSNFLGGGY 60), 20547 (61 SAALKLVNSKKSGTNVNVTKY 80) and 20548 (81 NSENTNTNNNIPESSSTYTN 100) were located in the conserved amino terminal region, as well as peptide 20548 which shared the sequence with the M region (amino acids 85-134). Six HABPs were located in region 10 (Rp10) (STDNNNTKTI). HABPs 20569 (501 TSDDELNKDSCDYSEEKENI 520) and 20570 (521 KSMINAYLDKLDLETVRKIH 40) were found in 3 non-repeat region. All these HABPs showed saturable binding and presented dissociation constants between 18 and 219 nM. The number of binding sites per Hep G2 cell ranged from 45,000 to 370,000. High binding peptides' critical amino acids involved in Hep G2 cell binding were determined by competition binding assays. SDS-PAGE results showed that both peptides 20570 and 20547 had at least two different sets of 44 and 38 kDa HABP receptors on Hep G2 cells. Specific modification of peptide 20546 and 20570 critical binding residues rendered these peptides immunogenic in Aotus monkeys, inducing high antibody titres against sporozoites, as assessed by IFA.

Biophysical Journal, 2019

Circular dichroism (CD) spectroscopy is a powerful technique to study the secondary structure of ... more Circular dichroism (CD) spectroscopy is a powerful technique to study the secondary structure of certain biomolecules such as proteins. Numerous approaches are based on the analysis of CD spectra to elucidate the percentage of structural components. Some of the most successful methods of this type, e.g. BeStSel, take into account the morphological and spectral diversity of the distinct secondary structures. Here, we present a different kind of approach that is based on the classical theory of optical activity. From the analysis of synchrotron radiation CD spectra, we estimate an effective complex polarizability (ECP) per residue of each type of secondary structure, which can be defined by a similar classification to the one proposed at BeStSel. The inputs of our model are the ECPs and the protein structure obtained from the PDB, and both allow us to calculate the corresponding CD spectrum. The approximated spectra are in good agreement with their experimental counterparts. Thus, this model could be used to describe conformational changes of a given protein.

Bioscience Reports, 2019

The trimeric heptad repeat domains HR1 and HR2 of the human immunodeficiency virus 1 (HIV-1) gp41... more The trimeric heptad repeat domains HR1 and HR2 of the human immunodeficiency virus 1 (HIV-1) gp41 play a key role in HIV-1-entry by membrane fusion. To develop efficient inhibitors against this step, the corresponding trimeric-N36 and C34 peptides were designed and synthesized. Analysis by circular dichroism of monomeric and trimeric N36 and C34 peptides showed their capacities to adopt α-helical structures and to establish physical interactions. At the virological level, while trimeric-C34 conserves the same high anti-fusion activity as monomeric-C34, trimerization of N36-peptide induced a significant increase, reaching 500-times higher in anti-fusion activity, against R5-tropic virus-mediated fusion. This result was associated with increased stability of the N36 trimer peptide with respect to the monomeric form, as demonstrated by the comparative kinetics of their antiviral activities during 6-day incubation in a physiological medium. Collectively, our findings demonstrate that wh...

Revista Colombiana De Quimica, Nov 14, 2010

Journal of Cellular Biochemistry, 2010

Class I-restricted T cell associated molecule (CRTAM) is a member of the immunoglobulin superfami... more Class I-restricted T cell associated molecule (CRTAM) is a member of the immunoglobulin superfamily that complies with the structural characteristics of the JAM family of proteins and is phylogenetically more closely related to nectin-like proteins. Here we demonstrate for the first time, that CRTAM is expressed in epithelial cells along the lateral membrane and is important for early cell-cell contacts and cellsubstrate interactions. CRTAM is sensitive to intermediate filament disruption and treatment of monolayers with soluble CRTAM enhances cell-cell dissociation and lowers transepithelial electrical resistance. Incubation of newly plated cells with anti-CRTAM antibody decreases the formation of cell aggregates and promotes cell detachment. Co-cultures of epithelial cells and fibroblasts that lack CRTAM expression and in vitro binding assays, demonstrate the participation of CRTAM in homotypic and heterotypic trans-interactions. Hence we conclude that CRTAM is a molecule involved in epithelial cell adhesion.

Optical Materials, 2014

ABSTRACT Here is reported the use of a titanium oxide:fullerene (TiOx:PC71BM) composite film as e... more ABSTRACT Here is reported the use of a titanium oxide:fullerene (TiOx:PC71BM) composite film as electron collector layer in organic photovoltaic devices (OPV cells). OPV cells were fabricated under the bulk heterojunction architecture: the active layer was a blend of either the photoconductor polymer MEH-PPV or P3HT with the fullerene derivative PC71BM. As cathode the eutectic alloy of Bi, In and Sn, known as Field's metal, was used. The melting point of this alloy is above 62 degrees C, which makes it suitable for a vacuum-free deposition process and easy and fast device test. Cell fabrication and testing were carried out at normal room conditions. For OPV cells based on MEH-PPV, the composite thin electron collector layer improved the power conversion efficiency (eta) from 1.12% to 2.07%, thus the eta increase was about 85%. Meanwhile, for devices based on P3HT the use of the composite film improved the photocurrent in almost 1 mA/cm(2) and the efficiency slightly increase from 2.48% to 2.68%.

Journal of the American Chemical Society, 2007

Journal of Cellular Biochemistry, 2010

Class I-restricted T cell associated molecule (CRTAM) is a member of the immunoglobulin superfami... more Class I-restricted T cell associated molecule (CRTAM) is a member of the immunoglobulin superfamily that complies with the structural characteristics of the JAM family of proteins and is phylogenetically more closely related to nectin-like proteins. Here we demonstrate for the first time, that CRTAM is expressed in epithelial cells along the lateral membrane and is important for early cell-cell contacts and cellsubstrate interactions. CRTAM is sensitive to intermediate filament disruption and treatment of monolayers with soluble CRTAM enhances cell-cell dissociation and lowers transepithelial electrical resistance. Incubation of newly plated cells with anti-CRTAM antibody decreases the formation of cell aggregates and promotes cell detachment. Co-cultures of epithelial cells and fibroblasts that lack CRTAM expression and in vitro binding assays, demonstrate the participation of CRTAM in homotypic and heterotypic trans-interactions. Hence we conclude that CRTAM is a molecule involved in epithelial cell adhesion.

ChemMedChem, 2009

The aim of this study was to design synthetic peptides with D-amino acid substitutions that mimic... more The aim of this study was to design synthetic peptides with D-amino acid substitutions that mimic the human immunodeficiency virus (HIV) gp41 HR2 region. The objective was to develop new and active C34 analogue peptides by introducing D-amino acid point substitutions at nonessential sites for HR1-HR2 interaction without disrupting the structure of the peptide. Herein we report a study with C34L peptide analogues, including the enantiomer peptide C34D, the retro-inverso analogue (RI), and two peptides with D-amino acid point substitutions (C34M2 and C34M3). Our results show that, with the exception of RI, these peptides adopt an alpha-helical structure and are, like C34L, able to interact with HR1, mimicked by the N36 peptide. Furthermore, we show that modifications introduced in C34M2, but not in C34M3, enhance its resistance to trypsin-mediated hydrolysis and increase the stability of C34M2 in physiological medium. Interestingly, our results show that C34 peptide analogues C34M2 and C34M3, but not C34D and its RI analogue, retain their ability to inhibit HIV-1 replication with an efficiency similar to that of the C34L peptide. These data underscore the interest in using D-amino acids at specific sites in the C34 peptide sequence and may lead to a new strategy for the development of more stable and active anti-HIV-1 peptidic drugs.

The Journal of Peptide Research, 2002

Plasmodium falciparum in the experimental Aotus monkey model.

Applied Microbiology and Biotechnology, 2011

Revista Colombiana de Química, 2021

El parásito intracelular Leishmania braziliensis es el agente causal de la leishmaniasis cutánea,... more El parásito intracelular Leishmania braziliensis es el agente causal de la leishmaniasis cutánea, enfermedad endémica de zonas tropicales, cuyos tratamientos farmacológicos son tóxicos y para la cual no se dispone de una vacuna en la actualidad. Por esta razón, el estudio de las proteínas relacionadas con el metabolismo energético del parásito es relevante dada su importancia para la supervivencia del mismo. En este estudio, utilizando como secuencia plantilla los primeros 18 residuos del extremo N-terminal de la proteína nicotinamida/nicotinato mononucleótido adenilil transferasa de L. braziliensis (Lb-NMNAT), se sintetizaron péptidos implementando la estrategia Fmoc/tert-Butilo en una resina Rink amida MBHA. Los péptidos se purificaron por cromatografía en columna C18 y se caracterizaron mediante RP-HPLC. La proteína recombinante 6xHisLb-NMNAT se expresó en células Escherichia coli M15 y se purificó parcialmente empleando cromatografía de afinidad a metales inmovilizados. De esta ...

Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 2021

La nicotinamida/nicotinato mononucleótido adenililtransferasa (NMNAT, EC 2.7.7.1/18) desempeñauna... more La nicotinamida/nicotinato mononucleótido adenililtransferasa (NMNAT, EC 2.7.7.1/18) desempeñauna función central en la síntesis del dinucleótido de adenina y nicotinamida (NAD) debido a queen esta enzima confluyen las rutas de síntesis de novo y de reciclaje. El NAD es una moléculatrascendental en el metabolismo de todos los seres vivos, principalmente en el metabolismo redox. Eneste estudio se presenta una nueva estrategia metodológica para la evaluación de posibles inhibidoresde la NMNAT de Leishmania braziliensis (LbNMNAT). El método suprime la actividad inhibitoriacruzada con la enzima acoplada al ensayo de detección, la alcohol dehidrogenasa (ADH, EC 1.1.1.1).Experimentalmente se introdujo un paso intermedio de extracción en fase sólida de los inhibidoresantes de la ejecución del sistema enzimático de detección. La implementación del paso de extracciónposibilitó la evaluación específica de la enzima de interés, la LbNMNAT, sin afectar la enzimaacoplada ADH. El nuevo método per...

The Journal of Chemical Physics, 2020

We present a model of circular dichroism for proteins that is based on the classical electromagne... more We present a model of circular dichroism for proteins that is based on the classical electromagnetic theory for optical activity. The two additional constituents of the model are as follows: an appropriate characterization of the secondary structure of the protein residues and the assignment of an effective polarizability to each type of classified residue. The set of effective polarizabilities is obtained by means of a Monte Carlo statistical method, which is used to analyze a series of synchrotron radiation circular dichroism spectra together with their corresponding crystallographic structures. As a result, the predicted spectra from our model are in good accord with experimental data, as well as with the results of some other theoretical approaches.

Biophysical Journal, 2018

Journal of Physics: Conference Series, 2016

Quantum Mechanics is the favourite theory to predict the structure of any group of atoms, includi... more Quantum Mechanics is the favourite theory to predict the structure of any group of atoms, including biological molecules. Due to numerous difficulties, however, it is necessary to introduce a series of approximations to overcome such impediments. We present a coarse-grained model of circular dichroism (CD) that is based on the theory of optical activity, developed by DeVoe, in order to predict CD spectra. In first stage, we determine the polarisability of individual monomers (residues, in the case of peptides) from experiments of molar absorptivity. The complex polarisabilities are used together with peptide structures obtained by density functional theory and other methods to determine their corresponding CD spectra, which are in reasonable agreement with their experimental counterparts.

Vaccine, 2003

It has been demonstrated that Plasmodium falciparum sporozoite threonine-asparagine-rich protein ... more It has been demonstrated that Plasmodium falciparum sporozoite threonine-asparagine-rich protein (PfSTARP) is located on the sporozoite surface. This protein's non-overlapping consecutive peptides were synthesised and tested in Hep G2 cell binding assays. Twelve high activity binding peptides (HABPs) were identified in the resulting 31 peptides. Three were found in 5 non-repeat region (amino acids 41-80). Peptides 20546 (41 VIKHNRFLSEYQSNFLGGGY 60), 20547 (61 SAALKLVNSKKSGTNVNVTKY 80) and 20548 (81 NSENTNTNNNIPESSSTYTN 100) were located in the conserved amino terminal region, as well as peptide 20548 which shared the sequence with the M region (amino acids 85-134). Six HABPs were located in region 10 (Rp10) (STDNNNTKTI). HABPs 20569 (501 TSDDELNKDSCDYSEEKENI 520) and 20570 (521 KSMINAYLDKLDLETVRKIH 40) were found in 3 non-repeat region. All these HABPs showed saturable binding and presented dissociation constants between 18 and 219 nM. The number of binding sites per Hep G2 cell ranged from 45,000 to 370,000. High binding peptides' critical amino acids involved in Hep G2 cell binding were determined by competition binding assays. SDS-PAGE results showed that both peptides 20570 and 20547 had at least two different sets of 44 and 38 kDa HABP receptors on Hep G2 cells. Specific modification of peptide 20546 and 20570 critical binding residues rendered these peptides immunogenic in Aotus monkeys, inducing high antibody titres against sporozoites, as assessed by IFA.

Biophysical Journal, 2019

Circular dichroism (CD) spectroscopy is a powerful technique to study the secondary structure of ... more Circular dichroism (CD) spectroscopy is a powerful technique to study the secondary structure of certain biomolecules such as proteins. Numerous approaches are based on the analysis of CD spectra to elucidate the percentage of structural components. Some of the most successful methods of this type, e.g. BeStSel, take into account the morphological and spectral diversity of the distinct secondary structures. Here, we present a different kind of approach that is based on the classical theory of optical activity. From the analysis of synchrotron radiation CD spectra, we estimate an effective complex polarizability (ECP) per residue of each type of secondary structure, which can be defined by a similar classification to the one proposed at BeStSel. The inputs of our model are the ECPs and the protein structure obtained from the PDB, and both allow us to calculate the corresponding CD spectrum. The approximated spectra are in good agreement with their experimental counterparts. Thus, this model could be used to describe conformational changes of a given protein.

Bioscience Reports, 2019

The trimeric heptad repeat domains HR1 and HR2 of the human immunodeficiency virus 1 (HIV-1) gp41... more The trimeric heptad repeat domains HR1 and HR2 of the human immunodeficiency virus 1 (HIV-1) gp41 play a key role in HIV-1-entry by membrane fusion. To develop efficient inhibitors against this step, the corresponding trimeric-N36 and C34 peptides were designed and synthesized. Analysis by circular dichroism of monomeric and trimeric N36 and C34 peptides showed their capacities to adopt α-helical structures and to establish physical interactions. At the virological level, while trimeric-C34 conserves the same high anti-fusion activity as monomeric-C34, trimerization of N36-peptide induced a significant increase, reaching 500-times higher in anti-fusion activity, against R5-tropic virus-mediated fusion. This result was associated with increased stability of the N36 trimer peptide with respect to the monomeric form, as demonstrated by the comparative kinetics of their antiviral activities during 6-day incubation in a physiological medium. Collectively, our findings demonstrate that wh...

Revista Colombiana De Quimica, Nov 14, 2010

Journal of Cellular Biochemistry, 2010

Class I-restricted T cell associated molecule (CRTAM) is a member of the immunoglobulin superfami... more Class I-restricted T cell associated molecule (CRTAM) is a member of the immunoglobulin superfamily that complies with the structural characteristics of the JAM family of proteins and is phylogenetically more closely related to nectin-like proteins. Here we demonstrate for the first time, that CRTAM is expressed in epithelial cells along the lateral membrane and is important for early cell-cell contacts and cellsubstrate interactions. CRTAM is sensitive to intermediate filament disruption and treatment of monolayers with soluble CRTAM enhances cell-cell dissociation and lowers transepithelial electrical resistance. Incubation of newly plated cells with anti-CRTAM antibody decreases the formation of cell aggregates and promotes cell detachment. Co-cultures of epithelial cells and fibroblasts that lack CRTAM expression and in vitro binding assays, demonstrate the participation of CRTAM in homotypic and heterotypic trans-interactions. Hence we conclude that CRTAM is a molecule involved in epithelial cell adhesion.

Optical Materials, 2014

ABSTRACT Here is reported the use of a titanium oxide:fullerene (TiOx:PC71BM) composite film as e... more ABSTRACT Here is reported the use of a titanium oxide:fullerene (TiOx:PC71BM) composite film as electron collector layer in organic photovoltaic devices (OPV cells). OPV cells were fabricated under the bulk heterojunction architecture: the active layer was a blend of either the photoconductor polymer MEH-PPV or P3HT with the fullerene derivative PC71BM. As cathode the eutectic alloy of Bi, In and Sn, known as Field's metal, was used. The melting point of this alloy is above 62 degrees C, which makes it suitable for a vacuum-free deposition process and easy and fast device test. Cell fabrication and testing were carried out at normal room conditions. For OPV cells based on MEH-PPV, the composite thin electron collector layer improved the power conversion efficiency (eta) from 1.12% to 2.07%, thus the eta increase was about 85%. Meanwhile, for devices based on P3HT the use of the composite film improved the photocurrent in almost 1 mA/cm(2) and the efficiency slightly increase from 2.48% to 2.68%.

Journal of the American Chemical Society, 2007

Journal of Cellular Biochemistry, 2010

Class I-restricted T cell associated molecule (CRTAM) is a member of the immunoglobulin superfami... more Class I-restricted T cell associated molecule (CRTAM) is a member of the immunoglobulin superfamily that complies with the structural characteristics of the JAM family of proteins and is phylogenetically more closely related to nectin-like proteins. Here we demonstrate for the first time, that CRTAM is expressed in epithelial cells along the lateral membrane and is important for early cell-cell contacts and cellsubstrate interactions. CRTAM is sensitive to intermediate filament disruption and treatment of monolayers with soluble CRTAM enhances cell-cell dissociation and lowers transepithelial electrical resistance. Incubation of newly plated cells with anti-CRTAM antibody decreases the formation of cell aggregates and promotes cell detachment. Co-cultures of epithelial cells and fibroblasts that lack CRTAM expression and in vitro binding assays, demonstrate the participation of CRTAM in homotypic and heterotypic trans-interactions. Hence we conclude that CRTAM is a molecule involved in epithelial cell adhesion.

ChemMedChem, 2009

The aim of this study was to design synthetic peptides with D-amino acid substitutions that mimic... more The aim of this study was to design synthetic peptides with D-amino acid substitutions that mimic the human immunodeficiency virus (HIV) gp41 HR2 region. The objective was to develop new and active C34 analogue peptides by introducing D-amino acid point substitutions at nonessential sites for HR1-HR2 interaction without disrupting the structure of the peptide. Herein we report a study with C34L peptide analogues, including the enantiomer peptide C34D, the retro-inverso analogue (RI), and two peptides with D-amino acid point substitutions (C34M2 and C34M3). Our results show that, with the exception of RI, these peptides adopt an alpha-helical structure and are, like C34L, able to interact with HR1, mimicked by the N36 peptide. Furthermore, we show that modifications introduced in C34M2, but not in C34M3, enhance its resistance to trypsin-mediated hydrolysis and increase the stability of C34M2 in physiological medium. Interestingly, our results show that C34 peptide analogues C34M2 and C34M3, but not C34D and its RI analogue, retain their ability to inhibit HIV-1 replication with an efficiency similar to that of the C34L peptide. These data underscore the interest in using D-amino acids at specific sites in the C34 peptide sequence and may lead to a new strategy for the development of more stable and active anti-HIV-1 peptidic drugs.

The Journal of Peptide Research, 2002

Plasmodium falciparum in the experimental Aotus monkey model.