1,721,043 research outputs found
Proton transfer in biological systems
No full textGensch T, Heberle J, Viappiani C. Proton transfer in biological systems. PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES. 2006;5(6):529-530
Data analysis in pulsed-laser, time-resolved photoacoustics: evaluation of errors distribution and confidence intervals
No full textReal time deconvolution of photoacoustic waveforms using nonlinear least squares methods has been successfully used to analyze the temporal profile of the heat released by molecular excited states. In the present work we investigate the statistical distribution of the errors by which the photoacoustic signal is affected. We introduce the χ2 test to judge the goodness of fitting and obtain the confidence intervals of the recovered parameters
Photodynamic treatment of pathogens
No full textThe current viral pandemic has highlighted the compelling need for effective and versatile treatments, that can be quickly tuned to tackle new threats, and are robust against mutations. Development of such treatments is made even more urgent in view of the decreasing effectiveness of current antibiotics, that makes microbial infections the next emerging global threat. Photodynamic effect is one such method. It relies on physical processes proceeding from excited states of particular organic molecules, called photosensitizers, generated upon absorption of visible or near infrared light. The excited states of these molecules, tailored to undergo efficient intersystem crossing, interact with molecular oxygen and generate short lived reactive oxygen species (ROS), mostly singlet oxygen. These species are highly cytotoxic through non-specific oxidation reactions and constitute the basis of the treatment. In spite of the apparent simplicity of the principle, the method still has to face important challenges. For instance, the short lifetime of ROS means that the photosensitizer must reach the target within a few tens nanometers, which requires proper molecular engineering at the nanoscale level. Photoactive nanostructures thus engineered should ideally comprise a functionality that turns the system into a theranostic means, for instance, through introduction of fluorophores suitable for nanoscopy. We discuss the principles of the method and the current molecular strategies that have been and still are being explored in antimicrobial and antiviral photodynamic treatment
Kinetics of histidine dissociation from the heme Fe(III) in N-fragment (residues 1-56) of cytochrome c
No full textWe have here investigated the dissociation kinetics of the His side chains axially ligated to the heme-iron in the ferric (1-56 residues) N-fragment of horse cyt c. The ligand deligation induced by acidic pH-jump occurs as a biexponential process with different pre-exponential factors, consistent with a structural heterogeneity in solution and the presence of two differently coordinated species. In analogy with GuHCl-denatured cyt c, our data indicate the presence in solution of two ferric forms of the N-fragment characterized by bis-His coordination, as summarized in the following scheme: His18-Fe(III)-His26 (-->)(<--) His18-Fe(III)-His33. We have found that the pre-exponential factors depend on the extent of the pH-jump. This may be correlated with the different pK(a) values shown by His26 and His33; due to steric factors, His26 binds to the heme-Fe(III) less strongly than His33, as recently shown by studies on denatured cyt c. Interestingly, the two lifetimes are affected by temperature but not by the extent of the pH-jump. The lower pK(a) for the deligation reaction required the use of an improved laser pH-jump setup, capable of inducing changes in H+ concentration as large as 1 mM after the end of the laser pulse. For the ferric N-fragment, close activation entropy values have been determined for the two histidines coordinated to the iron; this result significantly differs from that for GuHCl-denatured cyt c, where largely different values of activation entropy were calculated. This underlines the role played by the missing segment (residues 57-104) peptide chain in discriminating deligation of the "nonnative'' His from the sixth coordination position of the metal
A novel targeting approach for melanoma cancer treatment based on photodynamic therapy
No full textPhotosensitizing molecules have been at the basis of photodynamic therapy (PDT) since its early development in the 1950s. The therapy is a selective treatment method based on the administration of a photosensitizer to diseased cells: when irradiated with visible light of suitable wavelength, the photoactivated molecule starts a cascade of molecular transitions leading to cytotoxic effects in the targeted cells. The achievement of effective bio-compounds with photosensitizing capabilities and increased selectivity towards specific tumors is at the heart of the current research in the field. The aim of the herein project is to create an all-in-one multifunctional bio-molecule to be used in PDT treatments for melanoma cancer cells and holding targeting, imaging and photosensitizing potential
Light Induced Protein Matrix Decoupling and Protein Relaxation in Dry Samples of Trehalose Coated MbCO at Room Temperature
No full textSIBPA on the crest of the Adriatic Sea wave: Introduction to the SIBPA XXIV (2018 congress) special issue
No full textThe Italian Society for Pure and Applied Biophysics (SIBPA) held its XXIV National Congress in the beautiful seaside town of Ancona, Italy, on September 10–13, 2018. This special issue features a selection of contributions from the Congress in all areas of modern biophysics including molecular, cellular, applied, computational and nanoscale biophysics. SIBPA pursues its institutional tasks and carries on its successful promotion of biophysical disciplines at the national and international levels, also trough the consolidation of its partnership with Biophysical Chemistry and Elsevier
SIBPA under the Tuscan sun: Introduction to the SIBPA XXIII Special Issue
No full textThe Italian Society for Pure and Applied Biophysics (SIBPA) held its XXIII National Congress in the gorgeous Tuscan town of Cortona, Italy, on September 18-21, 2016. This special issue features a selection of contributions from the Congress in the areas of molecular, applied, cellular and computational biophysics. Cutting-edge developments in nanoscale biophysics were introduced for the first time in the program. SIBPA continues its successful promotion of biophysical disciplines at the national and international levels, with added strength from its partnership with Biophysical Chemistry and Elsevier
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