Search

Your search keyword '"Lorente, Carolina"' showing total 272 results
Start Over Author "Lorente, Carolina"
272 results on '"Lorente, Carolina"'

7. Photosensitization of peptides and proteins by pterin derivatives

Author

Dantola Maria Laura, Reid Lara O., Castaño Carolina, Lorente Carolina, Oliveros Esther, and Thomas Andrés H.

Subjects
electron transfer, photosensitization, proteins, pterins, uv-a radiation, Crystallography, QD901-999
Abstract

Proteins are one of the preferential targets of the photosensitized damaging effects of ultraviolet (UV) radiation on biological system. Pterins belong to a family of heterocyclic compounds, which are widespread in living systems and participate in relevant biological functions. In pathological conditions, such as vitiligo, oxidized pterins accumulate in the white skin patches of patients suffering this depigmentation disorder. It is known that pterins are able to photosensitize damage in nucleotides and DNA by type I (electron transfer) and type II (singlet oxygen) mechanisms. Recently, it has been demonstrated that proteins and its components may also be damaged when solutions containing both proteins and pterin are exposed to UV-A radiation. Therefore, given the biological and medical relevance of the photosensitizing properties of these molecules, we present in this article an overview of the capability of different pterin derivatives to photoinduce damage in proteins present in the skin, focusing our attention on the chemical modifications of tyrosine and tryptophan residues.

Published
2017
Full Text
View/download PDF

12. Avoiding One‐Electron Oxidation of Biomolecules by 3,4‐Dihydroxy‐L‐Phenylalanine (DOPA)†.

Author

Neyra Recky, Jael R., Dántola, M. Laura, and Lorente, Carolina

Subjects
DOPA, BIOMOLECULES, EXCITED states, RADICALS (Chemistry), HISTIDINE, OXIDATION
Abstract

It has been proposed that 3,4‐dihydroxy‐L‐phenylalanine (DOPA) has antioxidant properties, and thus, the objective of this work was to evaluate the effect of adding DOPA during the photosensitized oxidation of tyrosine (Tyr), tryptophan (Trp), histidine (His), 2′‐deoxyguanosine 5′‐monophosphate (dGMP) and 2′‐deoxyadenosine 5′‐monophosphate (dAMP). It was observed that, upon pterin‐photosensitized degradation of a given biomolecule in acidic aqueous solutions, the rate of the biomolecule consumption decreases due to the presence of DOPA. Although DOPA deactivates the excited states of pterin (Ptr), biomolecules do as well, being the bimolecular quenching constants in the diffusional control limit, indicating that DOPA antioxidant mechanism is not a simple deactivation of Ptr excited states. Laser flash photolysis experiments provide evidence of the formation of DOPA radical (DOPA(–H)•, λMAX 310 nm), which is formed in a timescale longer than Ptr triplet excited state (3Ptr*) lifetime, ruling out its formation in a reaction between DOPA and 3Ptr*. The experimental results presented in this work indicate that the observed decrease on the rate of each biomolecule consumption due to the presence of DOPA is through a second one‐electron transfer reaction from DOPA to the biomolecule radicals. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

16. Electron Transfer Initiated Reactions Photoinduced by Pterins

Author

Lorente Carolina, Petroselli Gabriela, Dántola M. Laura, Oliveros Esther, and Thomas Andrés H.

Subjects
pterins, electron transfer, photosensitization, superoxide anion, Crystallography, QD901-999
Abstract

Interest in the photochemistry and photophysics of pterins has increased since the participation of this family of compounds in different photobiological processes has been suggested or demonstrated in recent decades. Pterins participate in relevant biological processes, such as metabolic redox reactions, and can photoinduce the oxidation of biomolecules through both electron transfer mechanisms (Type I) and singlet oxygen production (Type II). This article describes recent findings on electron transfer-initiated reactions photoinduced by the triplet excited state of pterins and connects them in the context of photosensitized processes of biological relevance.

Published
2011
Full Text
View/download PDF

23. Photosensitized Dimerization of Tyrosine: The Oxygen Paradox†.

Author

Dántola, M. Laura, Neyra Recky, Jael R., Lorente, Carolina, and Thomas, Andrés H.

Subjects
DIMERIZATION, TYROSINE, OXYGEN, PHOTOSENSITIZATION, DIMERS
Abstract

In electron‐transfer initiated photosensitization processes, molecular oxygen (O2) is not involved in the first bimolecular event, but almost always participates in subsequent steps giving rise to oxygenated products. An exception to this general behavior is the photosensitized dimerization of tyrosine (Tyr), where O2 does not participate as a reactant in any step of the pathway yielding Tyr dimers (Tyr2). In the pterin (Ptr) photosensitized oxidation of Tyr, O2 does not directly participate in the formation of Tyr2 and quenches the triplet excited state of Ptr, the reactive species that initiates the process. However, O2 is necessary for the dimerization, phenomenon that we have named as the oxygen paradox. Here, we review the literature on the photosensitized formation of Tyr2 and present results of steady‐state and time resolved experiments, in search of a mechanistic model to explain the contradictory role of O2 in this photochemical reaction system. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

24. Photoinduced cleavage of plasmid DNA in the presence of pterin

Author

Lorente Carolina, Thomas Andrés Héctor, Villata Laura Sofia, Hozbor Daniela, Lagares Antonio, and Capparelli Alberto

Subjects
Crystallography, QD901-999
Abstract

The photoinduced cleavage of plasmid DNA by UV -A light in the presence of pterin was investigated. Electrophoretic analysis of the irradiated plasmid pUCI8 in the presence of pterin showed that UV light of 350 nm induced the transformation of a significant proportion of the supercoiled plasmid to its relaxed form. A minor proportion of plasmid forms are also converted to the linear plasmid isomer at the longer irradiation times. All these transformations during irradiation can be observed in the absorption spectrum of DNA as function of time. Such spectral modifications correlated with the extent and the kinetics of plasmid relaxation, but not with the appearance of the linear plasmid. None of the exchanges were operative without the irradiation with UV-A light. Control experiments with pterin or plasmid DNA irradiated separately, showed no photochemical changes. Results taken together suggest that the observed changes in the supercoiled plasmid as well as the spectral modifications both derive from the generation of single-strand break in the DNA.

Published
2000
Full Text
View/download PDF

25. Oxidation of biomolecules photosensitized by pterin derivatives

Author

Dantola, Maria Laura, Vignoni, Mariana, Serrano, Mariana Paula, Lorente, Carolina, and Thomas, Andrés Héctor

Subjects
purl.org/becyt/ford/1 [https], purl.org/becyt/ford/1.4 [https], Proteins, DNA, Photosensitization, Lipid, Pterins
Abstract

La importancia biológica y médica de las reacciones fotosensibilizadas se relaciona principalmente con su participación en los procesos involucrados en el desarrollo de cáncer de piel y de terapias fotodinámicas para el tratamiento del cáncer e infecciones. Las pterinas, son una familia de compuestos heterocíclicos derivados de la 2-amino-4-pterinidinona, que se encuentran ampliamente distribuidas en los sistemas vivos participando de importantes funciones biológicas. En condiciones patológicas, como es el caso del vitiligo, pterinas oxidadas se acumulan en las manchas blancas de la piel de los pacientes que sufren este desorden de la pigmentación. Estas moléculas son fotoquímicamente activas, bajo radiación UV-A (320 – 400 nm), fluorescen, producen radicales orgánicos y especies reactivas de oxígeno, y también sufren reacciones de fotooxidación. Nuestro grupo de investigación, ha estudiado desde hace más de 20 años, la degradación fotosensibilizada por pterinas de biomoléculas tales como ADN, proteínas, lípidos y sus componentes. Los resultados experimentales incluyen análisis cinético, evaluación de la interacción entre los estados excitados de las pterinas con diferentes sustratos, detección de especies radicalarias, y la identificación de productos bajo diferentes condiciones experimentales. Dependiendo de la molécula blanco, las pterinas pueden fotosensibilizar la oxidación de las mismas por mecanismo tipo I (transferencia de electrones) o tipo II (oxígeno singlete, 1 O2), o una combinación de ambos. En este artículo, presentamos un resumen de los cambios químicos fotosensibilizados por pterinas bajo irradiación UV-A en diferentes biomoléculas y los mecanismos involucrados. The biological and medical importance of photosensitized reactions is mainly related to their participation in processes involved in the development of skin cancer and in photodynamic treatments against cancer and infections. Pterins, a family of heterocyclic compounds derived from 2-aminopteridin-4(1H)-one, are widespread in living systems and participate in important biological functions. In pathological conditions, such as vitiligo, oxidized pterins accumulate in the white skin patches of patients suffering this depigmentation disorder. These molecules are photochemically active and, under UV-A excitation (320– 400 nm), they can fluoresce, produce organic radicals and reactive oxygen species and undergo photooxidation. Our research group has investigated for more than 20 years the degradation of biomolecules such as DNA, proteins, lipids, and their components, photosensitized by pterins under UV-A irradiation. The experimental results include kinetics analysis, evaluation of interaction between pterins excited states with different substrates, detection of radical species, and identification of products, under different experimental conditions. Depending on the target molecule, pterin-photosensitized oxidations may be purely type I (electron transfer) or type II (singlet oxygen, 1 O2), or a combination of both. In this article, we present a summary of the chemical changes photoinduced by pterins upon UV-A irradiation in different biomolecules and the mechanisms involved. Fil: Dantola, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina Fil: Vignoni, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina Fil: Serrano, Mariana Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina Fil: Lorente, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina Fil: Thomas, Andrés Héctor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina

Published
2020

41. Distribución de subtipos moleculares de adenocarcinoma de pulmón y resultados clínicos en un centro de Argentina

Author

Recondo, Gonzalo, Denninghoff, Valeria Cecilia, Cuello, Maria T., Lorente, Carolina, Greco, Martin, de la Vega, Máximo, and Avagnina, Alejandra

Subjects
lcsh:Immunologic diseases. Allergy, Male, Proto-Oncogene Proteins B-raf, CIENCIAS MÉDICAS Y DE LA SALUD, Lung Neoplasms, Biopsy, Argentina, lcsh:Medicine, Medicina Clínica, Kaplan-Meier Estimate, Adenocarcinoma, survival, Statistics, Nonparametric, Oncología, lcsh:Infectious and parasitic diseases, Proto-Oncogene Proteins p21(ras), purl.org/becyt/ford/3.2 [https], Humans, lcsh:RC109-216, Anaplastic Lymphoma Kinase, Prospective Studies, In Situ Hybridization, Fluorescence, Aged, molecular subtypes, lcsh:R, Genes, erbB-1, Middle Aged, Immunohistochemistry, lung cancer, Protein Transport, Mutation, purl.org/becyt/ford/3 [https], Female, lcsh:RC581-607
Abstract

La prevalencia de alteraciones en oncogenes en adenocarcinoma de pulmón varía en nuestra región. El objetivo fue describir la prevalencia de mutaciones en KRAS, BRAF y EGFR y las translocaciones de ALK en pacientes con adenocarcinoma de pulmón y estudiar la supervivencia de acuerdo a subtipos moleculares. Se incluyeron pacientes con biopsias adecuadas para el estudio. Se evaluó el estado mutacional de KRAS, BRAF y EGFR por secuenciación con la técnica de Sanger. Las translocaciones de ALK se estudiaron por hibridación in situ por fluorescencia (FISH) e inmunohistoquimica (IHQ) contra ALK (clones D5F3 y 5A4). De 118 pacientes evaluados, se incluyeron 84 (72%) con análisis molecular completo. Se detectaron mutaciones de KRAS en 16 muestras (19%), EGFR en 11 (13%), y BRAF en 1 muestra (1%). Se detectaron rearreglos de ALK en 3 muestras (4%). La mediana de seguimiento de los pacientes fue de 42.4 [rango intercuatilo (RIC): 27.0-64.2] meses. Globalmente, la mediana de supervivencia en la población fue 10.3 [RIC: 5.6-20.2] meses y fue de 10.8 [RIC: 6.0 20.3] meses en pacientes sin alteraciones moleculares detectables. La mediana de supervivencia de los pacientes con mutación en KRAS fue de 9.6 [RIC: 3.7-16.1] meses (HR: 1.08; p = 0.82) y 32.5 [RIC: 19.6-38.4] meses en el grupo con rearreglos de ALK o mutaciones en EGFR tratados con inhibidores de tirosina quinasa (HR: 0.27; p = 0.03). En conclusión, la prevalencia de alteraciones moleculares en nuestra población fue similar a otros países occidentales. The prevalence of relevant oncogenic drivers in lung adenocarcinoma varies in our region and data on clinical outcomes is scarce. The objective of the study was to describe the prevalence of KRAS, BRAF and EGFR mutations and ALK translocations in patients with advanced lung adenocarcinoma, and to depict the clinical outcome according to treatment strategies. Patients with adequate tumor biopsy sampling were included. KRAS, BRAF and EGFR mutations were studied by Sanger sequencing. ALK translocations were studied by fluorescent in situ hybridization (FISH) and immunohistochemistry (IH) with antibodies against ALK with clones D5F3 and 5A4. Informed consent was signed by 118 patients and 84 (72%) with complete molecular analysis were included. KRAS mutations were detected in 16 samples (19%), EGFR in 11 (13%), 9 of them conferring sensitivity to EGFR inhibitors, and BRAF mutations in 1 (1%). ALK translocations were detected in 3 samples (4%). Median follow-up was 42.4 [interquartile range (IQR): 27.0-64.2] months. Globally, median overall survival was 10.3 [IQR: 5.6-20.2] months. Median survival was 10.8 [IQR: 6.0-20.3] months in the group of patients without detectable molecular alteration, 9.6 [IQR: 3.7-16.1] months in KRAS mutant population (HR: 1.08; p = 0.82) and 32.5 [IQR: 19.6-38.4] months in patients with ALK translocations or sensitizing EGFR mutated tumors treated with tyrosine kinase inhibitors (HR: 0.27; p = 0.03). In conclusion, the prevalence of molecular alterations and outcomes in our population is similar to that reported in other studies in Western countries. Fil: Recondo, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentina Fil: Denninghoff, Valeria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentina Fil: Cuello, Maria T.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentina Fil: Lorente, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentina Fil: Greco, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentina Fil: de la Vega, Máximo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentina Fil: Avagnina, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentina Fil: Recondo, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentina

Published
2018

46. Type I Photosensitized Oxidation of Methionine†.

Author

Castaño, Carolina, Thomas, Andrés H., and Lorente, Carolina

Subjects
RADICAL anions, ESSENTIAL amino acids, METHIONINE, RADICAL cations, OXIDATION, CHARGE exchange, CHEMICAL kinetics
Abstract

Methionine (Met) is an essential sulfur‐containing amino acid, sensitive to oxidation. The oxidation of Met can occur by numerous pathways, including enzymatic modifications and oxidative stress, being able to cause relevant alterations in protein functionality. Under UV radiation, Met may be oxidized by direct absorption (below 250 nm) or by photosensitized reactions. Herein, kinetics of the reaction and identification of products during photosensitized oxidation were analyzed to elucidate the mechanism for the degradation of Met under UV‐A irradiation using pterins, pterin (Ptr) and 6‐methylpterin (Mep), as sensitizers. The process begins with an electron transfer from Met to the triplet‐excited state of the photosensitizer (Ptr or Mep), to yield the corresponding pair of radicals, Met radical cation (Met•+) and the radical anion of the sensitizer (Sens•−). In air‐equilibrated solutions, Met•+ incorporates one or two atoms of oxygen to yield methionine sulfoxide (MetO) and methionine sulfone (MetO2), whereas Sens•− reacts with O2 to recover the photosensitizer and generate superoxide anion (O2•−). In anaerobic conditions, further free‐radical reactions lead to the formation of the corresponding dihydropterin derivatives (H2Ptr or H2Mep). [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

47. Fotosensibilización de nucleótidos por pterina

Author

Estébanez Ruiz, Sandra, Lorente, Carolina, and Thomas, Andrés Héctor

Subjects
fotosensibilización, nucleótidos, pterinas, Química, Ciencias Exactas
Abstract

Las pterinas son compuestos heterocíclicos presentes en gran variedad de sistemas vivos que participan en funciones biológicas importantes. Bajo excitación con luz UV-A pueden fluorescer, experimentar fotooxidación y generar especies reactivas de oxígeno. En presencia de oxígeno, actúan como fotosensibilizadores a través de un mecanismo tipo I y/o tipo II. Se realizaron estudios de degradación de 2'-desoxitimidina en presencia de pterina bajo radiación UV-A. Bajo condiciones anaeróbicas se observó la formación de aductos entre el sustrato y el fotosensibilizador. En presencia de O2 el estado excitado triplete de la pterina tiene un rol fundamental en el proceso fotosensibilizado, siendo el proceso un mecanismo de oxidación tipo I, que involucra la transferencia de electrones., Facultad de Ciencias Agrarias y Forestales

Published
2016

48. Oxidación de histidina fotosensibilizada por pterina: mecanismo dependiente del pH

Author

Castaño, Carolina, Thomas, Andrés Héctor, and Lorente, Carolina

Subjects
pterina, Pterinas, fotosensibilización, histidina, Química, Ciencias Exactas
Abstract

Las Pterinas son compuestos heterocíclicos que se encuentran en sistemas biológicos, se acumulan en la piel de pacientes que sufren vitíligo, un desorden de despigmentación crónica. En este trabajo, se investigó la habilidad de la Ptr, el compuesto principal de las pterinas oxidadas, de fotosensibilizar la oxidación de la histidina en solución acuosa bajo irradiación UV-A. La histidina es un aminoácido con un grupo imidazol, y está frecuentemente presente en los sitios activos de las enzimas. El resultado más importante en la dependencia de pH es la competencia ente los mecanismos de transferencia de electrones (Tipo I) y transferencia de energía (Tipo II). Por combinación de diferentes técnicas se estableció que el mecanismo Tipo I predomina a pH ácido, aunque el mecanismo Tipo II está presente pero es más predominante en medio alcalino., Facultad de Ciencias Agrarias y Forestales

Published
2016

Catalog

Books, media, physical & digital resources
See catalog results