Nanopore Analysis of Peptides and Proteins

Nanopore sensing is a single-molecule technique capable of detecting peptide and protein molecules by monitoring the change in current generated by their interaction with protein or solid-state nanopores in an applied electric field. The interaction of a small globular protein HPr and two of its mutants, with the aerolysin nanopore were analyzed and compared with earlier results obtained with the α-hemolysin nanopore. The HPr molecules interact differently with the two nanopores while the anatomy and net charge of the pores affect their translocation parameters. Cleavage of insulin’s disulfide bonds with the reducing agent TCEP and the release of the component polypeptides could also be detected by nanopore analysis. An alternating current field superimposed on the direct current field inhibited the translocation of a peptide with a permanent dipole moment, while another peptide with no dipole moment was less affected. The detection of conformational changes in peptides and small proteins caused by metal ion binding also proved possible. A Zn-finger protein was able to translocate the α-hemolysin pore in the absence of Zn(II), while mostly bumping events were observed when Zn(II) was added. By comparison, the FSD-1 protein, which folds into a Zn-finger motif by hydrophobic interactions alone, was not able to translocate. The metal binding ability of three prion peptides was studied with an α-hemolysin pore. The results clearly indicated that Cu(II) and Zn(II) bound to all three peptides and caused conformational changes reflected in their interaction parameters with the α-hemolysin pore. The interaction of HPr, calmodulin and maltose binding protein with 7 nm and 5 nm diameter silicon nitride (SixNy) pores indicated that protein molecules with dimensions comparable to, or larger than the pore diameter do not translocate. However, smaller proteins are able to translocate in a folded conformation. Finally, the formation of prion/antibody complexes was successfully detected with an 11 nm SixNy pore but not with a 19 nm pore. The results underline the importance of choosing a pore with a suitable diameter in relation to the size of the analytes

El paciente alcohólico en Atención Primaria. Revisión bibliográfica.

Introducción: El alcoholismo es una enfermedad que causa ansia, pérdida de control, dependencia física y tolerancia. En España, las personas que mantienen un consumo de riesgo representan el 9,3% de la población y solo dos de cada diez casos están diagnosticados, debido en parte a las deficiencias sanitarias que existen en su abordaje. Objetivos: Conocer el estado de la evidencia científica en relación con la atención al paciente alcohólico. Metodología: Se realizó una búsqueda bibliográfica electrónica en las siguientes bases de datos y buscadores: DIALNET, SCIELO, PUBMED, MEDLINE PLUS y SCIENCE DIRECT, durante el periodo comprendido entre Diciembre de 2018 y Febrero de 2019. Desarrollo: Se seleccionaron 22 artículos, agrupando los resultados en: factores causales, detección, intervención enfermera en atención primaria, barreras que dificultan el acceso al tratamiento, consumo de alcohol en adolescentes y mujeres, intervención en familiares de pacientes alcohólicos y tratamiento de la enfermedad. Conclusiones: Esta enfermedad se encuentra con muchas barreras en su detección y tratamiento. El consejo breve realizado en la consulta es una herramienta efectiva y de bajo coste en el manejo del paciente alcohólico. El papel de enfermería es capacitar a la población para alcanzar su plena salud potencial promoviendo asumir el control de todo lo que determine su estado de salud como se preconiza en la Carta de Otawa para la Promoción de la Salud. Palabras clave: Alcoholismo, atención primaria, dependencia alcohólica, prevención, salud familiar, enfermería y diagnóstico.<br /

Dendrimers in Nanoscale Confinement: The Interplay between Conformational Change and Nanopore Entrance

Hyperbranched dendrimers are nanocarriers for drugs, imaging agents, and catalysts. Their nanoscale confinement is of fundamental interest and occurs when dendrimers with bioactive payload block or pass biological nanochannels or when catalysts are entrapped in inorganic nanoporous support scaffolds. The molecular process of confinement and its effect on dendrimer conformations are, however, poorly understood. Here, we use single-molecule nanopore measurements and molecular dynamics simulations to establish an atomically detailed model of pore dendrimer interactions. We discover and explain that electrophoretic migration of polycationic PAMAM dendrimers into confined space is not dictated by the diameter of the branched molecules but by their size and generation-dependent compressibility. Differences in structural flexibility also rationalize the apparent anomaly that the experimental nanopore current read-out depends in nonlinear fashion on dendrimer size. Nanoscale confinement is inferred to reduce the protonation of the polycationic structures. Our model can likely be expanded to other dendrimers and be applied to improve the analysis of biophysical experiments, rationally design functional materials such as nanoporous filtration devices or nanoscale drug carriers that effectively pass biological pores