V-shape" molecular configuration of wax esters of jojoba oil in a Langmuir film model

The aim of the present work was to understand the interfacial properties of a complex mixture of wax esters (WEs) obtained from Jojoba oil (JO). Previously, on the basis of molecular area measurements, a hairpin structure was proposed as the hypothetical configuration of WEs, allowing their organization as compressible monolayers at the air-water interface. In the present work, we contributed with further experimental evidence by combining surface pressure (π), surface potential (ΔV), and PM-IRRAS measurements of JO monolayers and molecular dynamic simulations (MD) on a modified JO model. WEs were self-assembled in Langmuir films. Compression isotherms exhibited π lift-off at 100 Å 2 /molecule mean molecular area (A lift-off ) and a collapse point at π c ≈ 2.2 mN/m and A c ≈ 77 Å 2 /molecule. The ΔV profile reflected two dipolar reorganizations, with one of them at A > A lift-off due to the release of loosely bound water molecules and another one at A c < A < A lift-off possibly due to reorientations of a more tightly bound water population. This was consistent with the maximal SP value that was calculated according to a model that considered two populations of oriented water and was very close to the experimental value. The orientation of the ester group that was assumed in that calculation was coherent with the PM-IRRAS behavior of the carbonyl group with the C=O oriented toward the water and the C-O oriented parallel to the surface and was in accordance with their orientational angles (∼45 and ∼90°, respectively) determined by MD simulations. Taken together, the present results confirm a V shape rather than a hairpin configuration of WEs at the air-water interface.Fil: Caruso, Benjamin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Química. Cátedra de Química Biológica; ArgentinaFil: Martini, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Pickholz, Mónica Andrea. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Perillo, Maria Angelica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Química. Cátedra de Química Biológica; Argentin

In silico selection and evaluation of pugnins with antibacterial and anticancer activity using skin transcriptome of treefrog (Boana pugnax)

In order to combat bacterial and cancer resistance, we identified peptides (pugnins) with dual antibacterial l–anticancer activity from the Boana pugnax (B. pugnax) skin transcriptome through in silico analysis. Pugnins A and B were selected owing to their high similarity to the DS4.3 peptide, which served as a template for their alignment to the B. pugnax transcriptome, as well as their function as part of a voltage-dependent potassium channel protein. The secondary peptide structure stability in aqueous medium was evaluated as well, and after interaction with the Escherichia coli (E. coli) membrane model using molecular dynamics. These pugnins were synthesized via solid-phase synthesis strategy and verified by Reverse phase high-performance liquid chromatography (RP-HPLC) and mass spectrometry. Subsequently, their alpha-helix structure was determined by circular dichroism, after which antibacterial tests were then performed to evaluate their antimicrobial activity. Cytotoxicity tests against cancer cells also showed selectivity of pugnin A toward breast cancer (MFC7) cells, and pugnin B toward prostate cancer (PC3) cells. Alternatively, flow cytometry revealed necrotic cell damage with a major cytotoxic effect on human keratinocytes (HaCaT) control cells. Therefore, the pugnins found in the transcriptome of B. pugnax present dual antibacterial– anticancer activity with reduced selectivity to normal eukaryotic cells.Fil: Liscano, Yamil. Universidad Santiago de Cali; Colombia. Universidad de Antioquia; ColombiaFil: Medina, Laura. Universidad de Antioquia; ColombiaFil: Oñate Garzón, Jose. Universidad Santiago de Cali; ColombiaFil: Gúzman, Fanny. Pontificia Universidad Católica de Valparaíso; ChileFil: Pickholz, Mónica Andrea. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Delgado, Jean Paul. Universidad de Antioquia; Colombi

Study of the lamellar and micellar phases of pluronic F127: A molecular dynamics approach

In this work, we analyzed the behavior of Pluronic F127 through molecular dynamics simulations at the coarse-grain level, focusing on the micellar and lamellar phases. To this aim, two initial polymer conformations were considered, S-shape and U-shape, for both simulated phases. Through the simulations, we were able to examine the structural and mechanical properties that are difficult to access through experiments. Since no transition between S and U shapes was observed in our simulations, we inferred that all single co-polymers had memory of their initial configuration. Nevertheless, most copolymers had a more complex amorphous structure, where hydrophilic beads were part of the lamellar-like core. Finally, an overall comparison of the micellar a lamellar phases showed that the lamellar thickness was in the same order of magnitude as the micelle diameter (approx. 30 nm). Therefore, high micelle concentration could lead to lamellar formation. With this new information, we could understand lamellae as orderly packed micelles.Fil: Albano, Juan Manuel Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Grillo, Damián Alexis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Facelli, Julio C.. University of Utah; Estados UnidosFil: Ferraro, Marta Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Pickholz, Mónica Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin

Estudio de la interacción péptido-membrana utilizando simulaciones por Dinámica Molecular

Los péptidos antimicrobianos (PAMs) juegan un rol fundamental en el sistema de defensa de todos los organismos. En los eucariotas forman parte de su sistema inmune innato pero además pueden actuar modulando la respuesta inmune adquirida. Se trata de moléculas pequeñas, catiónicos y de naturaleza anfipática. Actúan mediante interacción con la membrana bacteriana: pueden adsorberse, insertarse o translocarse, produciendo la lisis o la permeabilización, formando poros o bien interaccionanando con proteínas de membrana. Además, algunos pueden autoensamblarse en estructuras oligoméricas u otros agregados. Estos mecanismos están relacionados con la estructura 3D y secuencia aminoacídica y, a menudo, implican estructuras transientes que son difíciles de estudiar experimentalmente. Esto impide el desarrollo de PAMs con alto valor terapéutico, lo cual requiere una comprensión detallada del mecanismo de acción Las simulaciones de dinámica molecular (DM) son una herramienta poderosa para comprender estos sistemas y sus procesos dinámicos. En este trabajo llevamos a cabo simulaciones de DM para somuncurin-1, un PAM aislado de la piel de la rana patagónica Pleurodema somuncurense, el cual mostró actividad moderada contra cepas de Escherichia coli y Staphylococcus aureus. Utilizamos dos tipos de bicapas lipídicas: mezclas POPC y POPG/POPE que imitan las membranas de mamíferos y bacterias, respectivamente, y nos centramos en los efectos cooperativos en la interacción de péptidos con bicapas lipídicas. Para obtener un buen muestreo distribuimos péptidos (alta concentración) en el núcleo hidrofóbico de interfase de agua. Las simulaciones se llevaron a cabo utilizando el conjunto NPT a tres temperaturas diferentes, 303K, 310K y 320K, para replicar el sistema al mismo tiempo que se aceleran algunos procesos. Somuncurin-1 mostró mayor afinidad por la interfase lipídica del modelo bacteriano. Además, fue posible acceder al mecanismo de estabilización peptídico en el núcleo hidrofóbico y un análisis posterior mostró las interacciones específicas responsables de esta localización. Si bien estos resultados nos permiten conocer el comportamiento de somuncurin-1 en un entorno de membranas, es necesario continuar con el análisis de las simulaciones para poder inferir cuál es su mecanismo de acción.Fil: Cancelarich, Natalia Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Pickholz, Mónica Andrea. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Domene, C.. University of Bath; Reino UnidoFil: Marani, Mariela Mirta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; Argentina9na Jornada de Becarios y 1er Encuentro Patagónico de BecariosPuerto MadrynArgentinaCentro Nacional PatagónicoUniversidad Nacional de la PatagoniaInstituto Nacional de Tecnología AgropecuariaConsejo Federal de InversionesUniversidad Tecnológica Naciona

Understanding Conformational Dynamics of Complex Lipid Mixtures Relevant to Biology

This is a perspective article entitled “Frontiers in computational biophysics: understanding conformational dynamics of complex lipid mixtures relevant to biology” which is following a CECAM meeting with the same name.Fil: Friedman, Ran. Linnæus University; ArgentinaFil: Khalid, Syma. University of Southampton; Reino UnidoFil: Aponte Santamaría, Camilo. Ruprecht-Karls-Universität Heidelberg; Alemania. Universidad de los Andes; ColombiaFil: Arutyunova, Elena. University of Alberta; CanadáFil: Becker, Marlon. Westfälische Wilhelms Universität; AlemaniaFil: Boyd, Kevin J.. University of Connecticut; Estados UnidosFil: Christensen, Mikkel. University Aarhus; DinamarcaFil: Coimbra, João T. S.. Universidad de Porto; PortugalFil: Concilio, Simona. Universita di Salerno; ItaliaFil: Daday, Csaba. Heidelberg Institute for Theoretical Studies; AlemaniaFil: Eerden, Floris J. van. University of Groningen; Países BajosFil: Fernandes, Pedro A.. Universidad de Porto; PortugalFil: Gräter, Frauke. Heidelberg University; Alemania. Heidelberg Institute for Theoretical Studies; AlemaniaFil: Hakobyan, Davit. Westfälische Wilhelms Universität; AlemaniaFil: Heuer, Andreas. Westfälische Wilhelms Universität; AlemaniaFil: Karathanou, Konstantina. Freie Universität Berlin; AlemaniaFil: Keller, Fabian. Westfälische Wilhelms Universität; AlemaniaFil: Lemieux, M. Joanne. University of Alberta; CanadáFil: Marrink, Siewert J.. University of Groningen; Países BajosFil: May, Eric R.. University of Connecticut; Estados UnidosFil: Mazumdar, Antara. University of Groningen; Países BajosFil: Naftalin, Richard. Colegio Universitario de Londres; Reino UnidoFil: Pickholz, Mónica Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Piotto, Stefano. Universita di Salerno; ItaliaFil: Pohl, Peter. Johannes Kepler University; AustriaFil: Quinn, Peter. Colegio Universitario de Londres; Reino UnidoFil: Ramos, Maria J.. Universidad de Porto; PortugalFil: Schiøtt, Birgit. University Aarhus; DinamarcaFil: Sengupta, Durba. National Chemical Laboratory India; IndiaFil: Sessa, Lucia. Universita di Salerno; ItaliaFil: Vanni, Stefano. University Of Fribourg;Fil: Zeppelin, Talia. University Aarhus; DinamarcaFil: Zoni, Valeria. University of Fribourg; SuizaFil: Bondar, Ana-Nicoleta. Freie Universität Berlin; AlemaniaFil: Domene, Carmen. University of Oxford; Reino Unido. University of Bath; Reino Unid

Naratriptan aggregation in lipid bilayers: perspectives from molecular dynamics simulations

In order to understand the interaction between naratriptan and a fully hydrated bilayer of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl-choline (POPC), we carried out molecular dynamics simulations. The simulations were performed considering neutral and protonated ionization states, starting from different initial conditions. At physiological pH, the protonated state of naratriptan is predominant. It is expected that neutral compounds could have larger membrane partition than charged compounds. However, for the specific case of triptans, it is difficult to study neutral species in membranes experimentally, making computer simulations an interesting tool. When the naratriptan molecules were originally placed in water, they partitioned between the bilayer/water interface and water phase, as has been described for similar compounds. From this condition, the drugs displayed low access to the hydrophobic environment, with no significant effects on bilayer organization. The molecules anchored in the interface, due mainly to the barrier function of the polar and oriented lipid heads. On the other hand, when placed inside the bilayer, both neutral and protonated naratriptan showed self-aggregation in the lipid tail environment. In particular, the protonated species exhibited a pore-like structure, dragging water through this environment.Fil: Wood, Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; ArgentinaFil: Pickholz, Mónica Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; Argentin

Molecular dynamics study of uncharged bupivacaine enantiomers in phospholipid bilayers

To investigate the effects of the uncharged bupivacaine (BVC) on the properties of model membranes of 1-palmitoyl- 2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC), we have performed a series of molecular dynamics simulations. A very particular characteristic of the local anesthetic BVC, that is being discuss in the recent literature, is that their enantiomers R-(þ) (R-BVC) and S-(À) (S-BVC) present different activities. In this way, we have studied both enantiomers in a POPC phospholipids bilayers at a high molar ratios [local anesthetic (LA):lipid of 1:3]. The simulations were able to capture important features of the BVC?phospholipid bilayer interactions: BVC molecules are found in the interior of the bilayer. The R-BVC enantiomerfollows a bimodal distribution with access to the water?lipid interface; while the S-BVC is found, in more uniformdistribution, at the hydrophobic region. A decrease in theacyl chain segment order parameters, SCD, compared to neatbilayers, is found. Furthermore, this behavior is morenoticeable for the R-BVC form. The found decrease in SCD isattributed to a larger accessible volume per lipid in the tailregion. Our results could help to understand the highertoxicity of this enantiomer. Fil: Martini, María Florencia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Pickholz, Mónica Andrea. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin

Triptan partition in model membranes

In this work, we report a molecular dynamics simulations study of protonated triptans, sumatriptan and naratriptan, in a fully hydrated bilayer of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl-choline (POPC). The simulations were carried out at two concentrations for each drug. Our results show partition between the lipid head-water interphase and water phase for both triptans, with increasing access to the water phase with increasing concentrations. The triptans were stabilized at the interphase through different specific interactions with the POPC bilayer such as hydrogen bonds, salt bridges, and cation-π. Besides, sumatriptan and naratriptan protonated molecules have no access to the hydrophobic region of the bilayer at the studied conditions. Similar results were found for both drugs, however protonated naratriptan shows slightly higher affinity for the water phase. This behavior was attributed to the bulky lateral amino group in its structure under the studied conditions (drugs were originally placed at the water phase). This work represents a first insight to the comprehensive understanding of triptan partition in model membranes.Fil: Wood, Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; ArgentinaFil: Pickholz, Mónica Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; Argentin

Similarities and differences of serotonin and its precursors in their interactions with model membranes studied by molecular dynamics simulation

In this work, we report a Molecular Dynamics (MD) simulations study of relevant biological molecules as serotonin (neutral and protonated) and its precursors, tryptophan and 5-hydroxy-tryptophan, in a fully hydrated bilayer of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl-choline (POPC). The simulations were carried out at the fluid lamellar phase of POPC at constant pressure and temperature conditions. Two guest molecules of each type were initially placed at the water phase. We have analyzed, the main localization, preferential orientation and specific interactions of the guest molecules within the bilayer. During the simulation run, the four molecules were preferentially found at the water-lipid interphase. We found that the interactions that stabilized the systems are essentially hydrogen bonds, salt bridges and cation-π. None of the guest molecules have access to the hydrophobic region of the bilayer. Besides, zwitterionic molecules have access to the water phase, while protonated serotonin is anchored in the interphase. Even taking into account that these simulations were done using a model membrane, our results suggest that the studied molecules could not cross the blood brain barrier by diffusion. These results are in good agreement with works that show that serotonin and Trp do not cross the BBB by simple diffusion.Fil: Wood, Irene. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Tecnologia Farmaceutica; Argentina;Fil: Martini, María Florencia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Tecnologia Farmaceutica; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina;Fil: Pickholz, Mónica Andrea. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Tecnologia Farmaceutica; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Molecular Dynamics Study on the Encapsulation of Prilocaine in Liposomes at Physiological pH

In this work, we investigated the concentration effects on the encapsulation of prilocaine (PLC), an aminoamide local anesthetic, into a small unilamellar liposome, at physiological pH. On the line of our previous work, we have carried out Molecular Dynamics (MD) simulations using a coarse grain (CG) model that allow us to reach the microsecond time scale. At physiological pH there is a partition between protonated and neutral PLCs. In order to estimate the protonated/neutral PLC ratio at physiological pH (7.4), we have used the Henderson-Hasselbach equation. We have studied three PLC:lipid molar concentrations, ranging between 10:10 to 1:4. We essentially found that all neutral PLC molecules rapidly diffuse into the hydrophobic region of the vesicle adopting an asymmetric bimodal distribution. Moreover, protonated PLC molecules partition between the external monolayer of the vesicle and the water phase, having a high rate of exchange between this two phases, with no access to the inner part of the liposome in a concentration dependent way. In this way, we found that the behavior of PLCs at physiological pH is a combination of high and low pH, especially at low concentration of local anesthetics.Fil: Giupponi, Giovanni. Universidad de Barcelona. Facultad de Física; España;Fil: Martini, María Florencia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina;Fil: Pickholz, Mónica Andrea. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina