Ortiz López, Antonio

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Ortiz López, Antonio

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Ortiz López, Antonio

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Universidad de Murcia. Departamento de Bioquímica y Biología MolecularA

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Open Access
Estimation of human bloodstains time since deposition using ATR-FTIR spectroscopy and chemometrics in simulated crime conditions
(Elsevier, 2024-06-26) Mengual-Pujante, Miguel; Peran, Antonio J.; Pérez Cárceles, María Dolores; Ortiz López, Antonio; Ciencias Sociosanitarias
Blood in the form of stains is one of the most frequently encountered fluid in crime scene. Estimation of the time since deposition (TSD) is of great importance to guide the police investigation and the clarification of criminal offences. The time elapsed since deposition is usually estimated by modelling the physicochemical degradation of blood biomolecules over time. This work shows an ATR-FTIR spectroscopy and chemometrics study to estimate TSD of bloodstains on various surfaces and under different ambient conditions (indoor and outdoor). For a period from 0 to 212 days, a total of 960 stains were analyzed. Most of the eleven partial least squares regression (PLSR) models obtained showed a good prediction capacity, with a Residual Predictive Deviation (RPD) value higher than 3, and R2 higher than 0.90. Models for non-rigid supports showed better predictive capacity than those for rigid ones. A non-rigid surface model including the various non-rigid surfaces and ambient conditions was elaborated, which might be the most useful one from the criminalistic point of view. These results show that this technique can be a rapid, robust, and trustable tool for in situ determination of the TSD of bloodstains at crime scenes.
Open Access
Anticarcinogenic trimethoxybenzoate of catechin stabilizes the liquid crystalline bilayer phase in phosphatidylethanolamine membranes
(Elsevier, 2022-11-11) Aranda, Elisa; Teruel Puche, José Antonio; Ortiz López, Antonio; Pérez Cárceles, María Dolores; Rodríguez López, José Neptuno; Aranda Martínez, Francisco José; Bioquímica y Biología Molecular A
The anticarcinogenic properties of catechins stand out among the great variety of biological actions attributed to these compounds. The capacity of catechins to interact with lipids and their participation in membrane related processes points out to the membrane as their potential site of action. Phosphatidylethanolamine is an abundant phospholipid in mammalian membranes that has tendency to form non lamellar phases, it is associated with important cellular processes, and it has been related to cancer. In order to shed light into the molecular effect of the anticarcinogenic 3,4,5- trimethoxybenzoate of catechin (TMBC) on lipid polymorphism and membrane structure and dynamics, we present a combined experimental and computational study of the interaction between this semisyn thetic catechin and biomimetic membranes composed of unsaturated phosphatidylethanolamine. Our experimental evidence reveals that TMBC is readily incorporated into unsaturated phos phatidylethanolamine system where it is able to shift the gel to liquid crystalline phase transition tem perature to lower values, decreasing the cooperativity and the enthalpy change of the transition. The presence of TMBC is able to promote the formation of gel phase immiscibility and to block the formation of the inverted hexagonal pha se. In the bilayer liquid crystalline phase, the catechin decreases the inter lamellar repeat distance, it increases the fluidity of the membrane, and it alters the hydrogen bond pat tern of the interfacial region of the bilayer. Our molecular dynamics results concur with the experimental data and locate TMBC forming different domains near the interfacial region of the bilayer where it mod ifies the lateral pressure profile of the membrane leading to a stabilization of the bilayer in the liquid crystalline phase and to a potential alteration of the function of the membrane
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Correlación entre la estructura de diferentes lípidos y su modulación de las propiedades físicas de membranas liposomales / Antonio López Ortiz ; director Juan Carmelo Gómez Fernández.
(Murcia : Universidad de Murcia, Departamento de Bioquímica y Biología Molecular,, 1987) Gómez Fernández, Juan Carmelo; Ortiz López, Antonio
Open Access
Estudio comparativo de la fauna de Carábidos de algunas lagunas de la región Manchego-Levantina (España). (Coleoptera: Adephaga)
(Murcia: Universidad de Murcia, Servicio de Publicaciones, 1988) Galián Albaladejo, José; Andújar, A.; Serrano, José; Ortiz López, Antonio; Facultad de Biología
Se ha estudiado la fauna de Carabidae de las lagunas saladas de Pétrola, el Saladar y el Saiobraiejo (este de Albacete), que se compara con la de un saladar sublitoral en Albatera (Alicante). Este parece ser potencial- mente más rico eri especies halobias que los del interior, mientras que parece ocumr lo contrario con las especies halófilas. Ello sugiere que la fauna halobia de Carabidae vana gradualmente con la altitud, lo que implica que las conclusiones de otros autores sobre este tipo de enclaves de la Península Ibérica deben ser modificadas
Open Access
Recent advances on the interaction of glycolipid and lipopeptide biosurfactants with model and biological membranes
(Elsevier, 2023-12) Terue, José A.; Aranda Martínez, Francisco José; Ortiz López, Antonio; Bioquímica y Biología Molecular A
Microbial biosurfactants have gained interest in the last de cades because of their unique characteristics. The variety of chemical structures within these compounds makes them very versatile, with glycolipids and lipopeptides outstanding among the rest. The amphiphilic nature of these compounds makes them to partition into and strongly interact with phospholipid membranes, modifying their structure and function. Thus, much research has been done on the characterization of the interaction of glycolipid and lipopeptide biosurfactants with model and biological membranes. Whereas the studies involving phospholipid model membranes were mostly carried out earlier, most of the recent research has focused on bio logical membranes, including mammalian and microorgan isms’ systems. This review presents the recent developments achieved on the interaction of the main glycolipid and lipo peptide biosurfactants with model and biological membranes.
Open Access
Separación de solutos no encapsulados en liposomas. Comparación de la filtración en gel con la centrifucación en minicolumnas de gel
(Murcia : Universidad de Murcia, 1986) Gómez Fernández, Juan Carmelo; Ortiz López, Antonio; Facultad de Veterinaria
Open Access
3,4,5-Trimethoxybenzoate of Catechin, an Anticarcinogenic Semisynthetic Catechin, Modulates the Physical Properties of Anionic Phospholipid Membranes
(MDPI, 2022-05-03) Aranda, Elisa; Pérez-Cárceles, María Dolores; Aranda Martínez, Francisco José; Ortiz López, Antonio; Rodríguez López, José Neptuno; Teruel Puche, José Antonio; Bioquímica y Biología Molecular A
3,4,5-Trimethoxybenzoate of catechin (TMBC) is a semisynthetic catechin which shows strong antiproliferative activity against malignant melanoma cells. The amphiphilic nature of the molecule suggests that the membrane could be a potential site of action, hence the study of its inter action with lipid bilayers is mandatory in order to gain information on the effect of the catechin on the membrane properties and dynamics. Anionic phospholipids, though being minor components of the membrane, possess singular physical and biochemical properties that make them physiologically essential. Utilizing phosphatidylserine biomimetic membranes, we study the interaction between the catechin and anionic bilayers, bringing together a variety of experimental techniques and molecular dynamics simulation. The experimental data suggest that the molecule is embedded into the phos phatidylserine bilayers, where it perturbs the thermotropic gel to liquid crystalline phase transition. In the gel phase, the catechin promotes the formation of interdigitation, and in the liquid crystalline phase, it decreases the bilayer thickness and increases the hydrogen bonding pattern of the interfacial region of the bilayer. The simulation data agree with the experimental ones and indicate that the molecule is located in the interior of the anionic bilayer as monomer and small clusters reaching the carbonyl region of the phospholipid, where it also disturbs the intermolecular hydrogen bonding between neighboring lipids. Our observations suggest that the catechin incorporates well into phos phatidylserine bilayers, where it produces structural changes that could affect the functioning of the membrane
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Effect of pH and temperature on the aggregation behaviour of dirhamnolipid biosurfactant. An experimental and molecular dynamics study
(Elsevier, 2021-04-05) Ortiz, Julia; Oliva, Alfonso; Teruel Puche, José Antonio; Aranda Martínez, Francisco José; Ortiz López, Antonio; Bioquímica y Biología Molecular A
Hypothesis: Pseudomonas aeruginosa dirhamnolipid (diRL) has been shown to form aggregates of different size and structure, under various conditions. Due to the presence of a carboxyl group in the molecule, it is expected that pH would strongly affect this aggregation behaviour. In addition, preliminary observations of temperature-induced changes in the states of aggregation of diRL supported the need of further investigation. Experiments: A systematic experimental study, using differential scanning calorimetry (DSC), small-angle Xray diffraction (SAXD), and Fourier-transform infrared pectroscopy (FTIR), has been carried out to charac terize pH and temperature driven changes in the aggregation behavior of diRL biosurfactant. Molecular dynamics (MD) simulations, supported by the experimental results, allowed depicting molecular details on formation of diRL membranes and other aggregated structures under various physicochemical conditions. Findings: DiRL could adopt fairly organizedmultilayered structures (membranes) at low pH and temperature, which became highly disordered upon increasing either of these parameters. The effect of pH on the gauche/ all-trans conformer ratio of the diRL acyl chains was not of significance, whereas temperature-induced effects were observed. For the first time it is described that diRL underwent an endothermic thermotropic transition with Tc = 34 C as observed by DSC, at pH 4.5 (protonated diRL), but not at pH 7.4 (unprotonated diRL). FTIR confirmed these findings, showing a significant additional disordering of the all-trans acyl chains upon increasing temperature around that same value in the protonated form, an effect not observed for the disso ciated form of the biosurfactant. In addition, at pH 7.4, changing temperature did not modify the hydration state of the polar moiety of diRL, whereas at pH 4.5 a significant decrease in the hydration state around 34 C took place. SAXD data showed that protonated diRL formed multilayered structures at 20 C, which con verted into poorly correlated layers at 50 C. MD simulations supported these findings, showing that the membrane-like structures formed by protonated diRL at 20 C became unstable at higher temperatures, tend ing to form other structures, which could be micelles or other type of layered structures, whereas the nega tively charged form of diRL organized in micelle-type aggregates in the whole range of temperature under study.
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Effect of a dirhamnolipid biosurfactant on the structure and phase behaviour of dimyristoylphosphatidylserine model membranes
(2019-10-19) Oliva, Alfonso; Aranda Martínez, Francisco José; Ortiz López, Antonio; Teruel Puche, José Antonio; Bioquímica y Biología Molecular A
Rhamnolipids are bacterial biosurfactants containing one or two rhamnose rings and a hydrophobic hydrocarbon portion. These compounds are mainly isolated from Pseudomonas spp culture media, and have been shown to present outstanding biological activities. A number of experimental works have shown that the interaction of rhamnolipids with target membranes could play a role in these actions. Therefore the study of the interaction of purified rhamnolipids with the various phospholipid components of biological membranes is of great interest. This paper shows the phase behaviour of mixtures of 1,2-dimyristolylphosphatidylserine (DMPS) with a dir hamnolipid (diRL) fraction produced by P. aeruginosa. This experimental approach has been based on the use of physical techniques such as Differential Scanning Calorimetry (DSC) and Fourier-Transform Infrared Spectroscopy (FTIR). DSC indicated that the presence of increasing concentrations of diRL in the bilayer resulted in a progressive broadening of the gel to liquid-crystalline phase transition of DMPS. In addition a complex thermal behaviour was observed, with the presence of more than one transition at higher concentrations of the biosurfactant, indicating phase separation. FTIR showed that diRL increased the proportion of gauche rotamers of DMPS, thus affecting acyl chain order. The change in the frequency of the carboxylate stretching band of DMPS observed upon interaction with diRL pointed toward changes in the local environment of the polar headgroup of the phospholipid, resulting in a modification of its conformation or insertion within the bilayer. This result was corroborated by the effect of diRL on the carbonyl and phosphate stretching bands of DMPS, showing an increase of the hydration both in the gel and in the liquid-crystalline phase. Molecular Dynamics (MD) simulations gave further support to the experimental results, showing diRL cluster formation as well as an augmented exposition of DMPS to the water layer in the presence of the biosurfactant.
Open Access
Caracterización del estado de acoplamiento de las preparaciones de retículo sarcoplásmico e interacción de la Ca2+.ATPasa con vanadato.
(Universidad, Servicio de Publicaciones, 1984) Ortiz López, Antonio
El estado de acoplamiento (relación Ca transportado/ATP hidrolizado) de las preparaciones de vesículas de retículo sarcoplásmico se puede determinar por medidas de actividad ATPasa dependiente de calcio por medio del uso de un pHmetro. Dicha relación se ha calculado en unos 2 moles Ca^/mol ATP, valor que está de acuerdo con los datos de la bibliografía. Se estudia el efecto del ionóforo de calcio X537A (lasalócido) y del detergente no iónico CuEg sobre las preparaciones de vesículas de retículo sarcoplásmico. Su acción se traduce en un aumento de la actividad ATPasa dependiente de calcio como consecuencia de que inducen un aumento de la permeabilidad de la membrana al Ca+, permaneciendo inalterada la ATPasa basal (independiente de calcio). Se describe un método de desacoplamiento de las preparaciones de vesículas de retículo sarcoplásmico, por tratamiento con EGTA a 37° C. Dicho desacoplamiento produce un significativo aumento de la actividad ATPasa dependiente de calcio no afectando a la actividad ATPasa basal. Se han utilizado preparaciones de ATPasa nativa, desacoplada por tratamiento con EGTA y purificada con detergentes (octilglucósido o colato), para estudiar la interacción de los iones vanadato con el enzima. La constante de disociación del complejo enzima-vanadato depende de la historia previa del enzima y, por lo tanto, se ha visto que son diferentes para las diferentes preparaciones mencionadas anteriormente. Se ha observado que la interacción del vanadato con la Ca^-ATPasa es un proceso lento, presentándose un proceso histerético cuando se ensaya actividad ATPasa, de vesículas preincubadas con vanadato, en presencia de los sustratos Ca^ y ATP.