Browsing by Author "Vergara Moreno, Esmeralda"
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Item Estudio de la interacción de un péptido catiónico derivado de la Cecropina-D Gallería mellonella con sistemas de modelos de membranas multilaminares que muestran similitud con las membranas bacterianas(Universidad Santiago de Cali, 2021) Ante Vasquez, Cristian Geovany; Vergara Moreno, Esmeralda; Oñate Garzón, Jose Fernando; Polo Cerón, DorianAntimicrobial peptides are of great importance in many living organisms, since they are part of the innate immune system, performing the role of effectors in defense against infectious agents. These are found in a great diversity of living beings, from which a great variety of these molecules have been isolated, such as CECROPINA-D from Galleria mellonella; the synthetic peptide M1 of 39 amino acids that has been obtained from the sequence of Cecropina Galleria mellonella, is a cationic homologue derived from the originally extracted peptide. It is known that the antimicrobial action of these molecules is due to the attraction of opposite charges that occur between the microbial membrane with an anionic charge and the peptide with cationic charge, therefore, it causes alterations in the change of phase resulting in an increase of the permeability of the membrane. However, there is not enough information about the mechanisms of action that peptides must cause the phase change of the membrane; In this work, the effect of the peptide on the thermotropic behavior of membrane models that simulate those of bacteria, consisting of DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) and DMPG (1,2 -Dimyristoyl-sn-glycero-3-phosphorylglycerol), respectively. Furthermore, an in-silico analysis allows us to recognize the peptide-membrane molecular interactions necessary to understand this effect. For both activities, the Differential Scanning Calorimetry (DCS) technique and Molecular Dynamics algorithms were implemented, respectively. The results confirmed the perturbation capacity of the M1 peptide. It is estimated that this capacity is given by the modulation of the physicochemical characteristics and parameters on the membrane models. A strong effect was observed in the multilamellar membranes (MLVs) formed by the mixture Phosphatidylcholine (DMPC) and Phosphatylglycerol (DMPG) in a ratio (3: 1), on the change from gel to crystalline phase with the presence of the peptide, reducing by 1, 7 ° C the temperature necessary for the transition. At 1:10 concentration of the peptide, a gel to crystalline phase change occurred without requiring energy supplied by an external system. In Molecular Dynamics, HB-type interactions were observed: hydrogen bonding; IE: electrostatic interaction; and HI: hydrophobic interaction present in the system for a time of 10 ns, distributed with data collection every 2 ns, finding a large presence of hydrogen bond-type interactions between peptide M1 and the rest of the system, with affinity for lipids of DMPG and absence of affinity with DMPC lipids, in addition the main amino acids that participated in these interactions were identified. Other data found and exposed in this work are the result of RMSD and the data of the results of the Radius of Gyration of peptide M1 in the system.