117,752 research outputs found
Correction to: A T-junction device allowing for two simultaneous orthogonal views: application to bubble formation and break-up (Microfluidics and Nanofluidics, (2018), 22, 8, (85), 10.1007/s10404-018-2101-1)
No full textThe article ‘A T-junction device allowing for two simultaneous orthogonal views: application to bubble formation and break-up’, written by Davide Caprini, Giorgia Sinibaldi, Luca Marino, Carlo Massimo Casciola was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 30 July 2018 without open access
"High-performance liquid displacement chromatography of enantiomers on a chiral poly-L-valyl-based stationary phase"
No full textA direct enantiomer separation according to the displacement mode of liquid chromatography has been developed on a silica-based stationary phase bearing as chiral selectors poly-L-valyl groups. Milligram amount resolution of DL-methionine β naphthylamide was accom plished on two analytical size columns using methanol-containing acetate buffer as the carrier and DL mande lie acid dissolved in the carrier as the displacer
Effect of axial coordination on the kinetics of assembly and folding of the two halves of horse heart cytochrome C.
No full textThe kinetics of the assembly of two complementary fragments of oxidized horse heart cytochrome c (cyt c), namely the heme-containing fragment-(1-56) and the fragment-(57-104), have been characterized at different pH values. At neutral pH the fragment-(1-56) is hexacoordinated and has two histidines axially ligated to the heme-Fe(III) (Santucci, R., Fiorucci, L., Sinibaldi, F., Polizio, F., Desideri, A., and Ascoli, F. (2000) Arch. Biochem. Biophys. 379, 331-336), thus mimicking what occurs in the folding intermediate of cyt c. The kinetics of the formation of the complex between the two fragments are characterized at pH 7.0 by a slow rate constant that is independent of the concentration of the reactants; conversely, at a low pH the kinetics are much faster and depend on the concentration of the fragments. This behavior suggests that the rate-limiting step observed in the recombination process of the fragments at neutral pH (that leads to the final coordination of Met-80) has to be ascribed to the detachment of the "misligated" histidine. Thus, the faster recombination rate at a low pH can be related to the fact that histidine is protonated and not able to coordinate to the metal. Furthermore, the independence of the rate constant on the concentration of the reactants observed at pH 7.0 can be accounted for by the occurrence of a conformational transition, which takes place immediately after the two fragments collapse together, likely simulating what induces the detachment of the misligated histidine during cytochrome folding
Enantiomeric resolution of DNS.amino acids by ligand exchange chromatography: Comparison of different chiral amino acid amides as additives to the mobile phase
No full textA study developing enantiomeric separations by metal chelate additives to the mobile phase in reversed-phase liquid chromatography is reported. In particular the use of Cu(II) complexes of L-prolinamide (L-ProNH2) and L-valinamide (L-ValNH2) is examined and discussed. Interestingly, for a series of DNS-amino acids these selectors show higher enantioselectivity than that obtained with the corresponding nonderivatized amino acid–Cu(II) complexe
Effect of axial coordination on the kinetics of assembly and folding of the two halves of horse heart cytochrome c
No full textThe kinetics of the assembly of two complementary fragments of oxidized horse heart cytochrome c (cyt c), namely the heme-containing fragment-(1-56) and the fragment-(57-104), have been characterized at different pH values. At neutral pH the fragment-(1-56) is hexacoordinated and has two histidines axially ligated to the heme-Fe(III) (Santucci, R., Fiorucci, L., Sinibaldi, F., Polizio, F., Desideri, A., and Ascoli, F. (2000) Arch. Biochem. Biophys. 379, 331-336), thus mimicking what occurs in the folding intermediate of cyt c. The kinetics of the formation of the complex between the two fragments are characterized at pH 7.0 by a slow rate constant that is independent of the concentration of the reactants; conversely, at a low pH the kinetics are much faster and depend on the concentration of the fragments. This behavior suggests that the rate-limiting step observed in the recombination process of the fragments at neutral pH (that leads to the final coordination of Met-80) has to be ascribed to the detachment of the "misligated" histidine. Thus, the faster recombination rate at a low pH can be related to the fact that histidine is protonated and not able to coordinate to the metal. Furthermore, the independence of the rate constant on the concentration of the reactants observed at pH 7.0 can be accounted for by the occurrence of a conformational transition, which takes place immediately after the two fragments collapse together, likely simulating what induces the detachment of the misligated histidine during cytochrome folding
Miti, interpretazioni e fraintendimenti: l'"autenticità" nella Convenzione UNESCO del 2003 e nella normativa italiana
No full textThe article focuses on one of the most critical issues when it comes to cultural heritage, namely the authenticity of a specific cultural practice and its role in the definition of a community identity. A fundamental characteristic for many UNESCO programs, authenticity is formally excluded from the text of the 2003 Convention for the Safeguarding of Intangible Cultural Heritage and from the Operational Directives; yet, in the application of these tools, it is one of the most problematic issues both for the communities of practitioners and for the bodies responsible for the protection of the registered elements, with clear implications of anthropological, political, and economic nature. The contribution reflects on the myth of authenticity and its declinations in terms of “ownership” and “exclusivity” of different cultural practices, approaching the analysis from a dual perspective: the regulatory developments at an international level and the most recent determinations of UNESCO are placed in dialogue with the legal and doctrinal interpretations in the Italian context, restoring the complexity of a subject in which demo-ethno-anthropological skills prove essential for the understanding of the law and its application to the concrete cases of human communities
Protein folding, unfolding and misfolding: Role played by intermediate states
No full textMost proteins fold into their native structure through well defined pathways which involve a limited number of transient intermediates. Intermediates play a relevant role in the folding process; many diseases of genetic nature are in fact coupled with protein misfolding due to formation of stable, inactive intermediate species of the protein. This review deals with a number of diseases associated with protein misfolding and briefly describes the mechanism(s) responsible, at molecular level, for such pathologies. It is also considered the (native ⇆ molten globule) transition, recently observed for some proteins, in which a native protein converts into a stable compact intermediate state able to carry out distinct physiological functions inside the cell. A non-native compact form of cyt c, for example, appears to have a role in the programmed cell death (apoptosis) after that the protein is released from the mitochondrion and non-native forms of the same protein appear involved in some of the disorders attributed to amyloid formation. © 2008 Bentham Science Publishers Ltd
Boundary conditions and infrared divergences
No full textWe review the procedure to construct quasi-free ground states, for real scalar fields whose dynamics is dictated by the Klein-Gordon equation, on standard static Lorentzian manifolds with a time-like boundary. We observe that, depending on the assigned boundary condition of Robin type, this procedure does not always lead to the existence of a suitable bi-distribution ω2∈D′(M×M) due to the presence of infrared divergences. As a concrete example we consider a Bertotti-Robinson spacetime in two different coordinate patches. In one case we show that infrared divergences do not occur only for Dirichlet boundary conditions as one might expect a priori, while, in the other case, we prove that they occur only when Neumann boundary conditions are imposed at the time-like boundary
Cytochrome c: An extreme multifunctional protein with a key role in cell fate
No full textCytochrome c, a protein that belongs to class 1 of the c-type cytochrome family, exerts different functions depending on its cellular localization and the conditions in which it operates; therefore, it can be defined as ‘extreme multifunctional’ protein. It mediates electron-transfer in the respiratory chain and acts as a detoxifying agent to dispose of ROS. In addition, cytochrome c plays a role in cell apoptosis. After its release into the cytosol, the protein binds to APAF-1, activates pro-caspase 9, and triggers an enzymatic cascade leading to cell death. The interaction with cardiolipin, one of the phospholipids making up the mitochondrial membrane, is essential to start apoptosis; the binding partially unfolds cytochrome c, alters the heme pocket region, and facilitates detachment of Met80 from the sixth coordination position of the heme iron. These events change the function of cytochrome c from an electron-transfer shuttle to a peroxidase-like hemoprotein, capable to trigger the process that leads to cell death. This review provides an overview of the key role played by the cytochrome c-cardiolipin interaction in apoptosis. This is not only important per se, it provides interesting perspectives for applications in clinical diagnostics that use the protein as a biomarker
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