Computational Identification of Uncharacterized Cruzain Binding Sites

Chagas disease, caused by the unicellular parasite Trypanosoma cruzi, claims 50,000 lives annually and is the leading cause of infectious myocarditis in the world. As current antichagastic therapies like nifurtimox and benznidazole are highly toxic, ineffective at parasite eradication, and subject to increasing resistance, novel therapeutics are urgently needed. Cruzain, the major cysteine protease of Trypanosoma cruzi, is one attractive drug target. In the current work, molecular dynamics simulations and a sequence alignment of a non-redundant, unbiased set of peptidase C1 family members are used to identify uncharacterized cruzain binding sites. The two sites identified may serve as targets for future pharmacological intervention

Application of FT-IR-ATR Spectroscopy to Evaluate the Penetration of Surface Sizing Agents into the Paper Structure

It is widely recognized that the surface properties of paper depend on the fibrous matrix and the final surface treatment applied to the paper. Regarding chemical paper surface treatments, an important issue is the evaluation of the penetration of chemical compounds into the fibrous matrix, as the chemicals can potentially cause changes in the intrinsic properties of paper. The work presented here aimed to use Fourier transform infrared (FT-IR) spectroscopy to study paper surface sizing, namely, the penetration of the sizing chemicals into the paper structure. Two different surface sizing formulations were applied to paper produced from Eucalyptus globulus bleached pulp (reference paper): both contain 90% (w/w) cationic starch, but one contains 10% (w/w) poly(styrene-co-maleic anhydride) whereas the other contains 10% (w/w) poly(styrene-co-butyl acrylate). The surface-sized paper sheets were further manually delaminated, so that the top surfaces as well as the internal layers could be analyzed by FT-IR spectroscopy. A non-surface-sized sample was taken as the reference. From the spectroscopic results, it was possible to detect the presence of the copolymers on the paper top surfaces, despite the application of only small amounts of these chemicals in the surface sizing. However, the chemicals were not found in the layers closest to the surface (30−40 μm from the top), leading to the conclusion that the penetration of the sizing formulations into the fibrous matrix was insignificant (at least up to this distance). Infrared spectroscopy data also showed that the calcium carbonate added as a filler was always present at higher concentration in the analyzed inner layers than at the top surface, for the reference paper as well as the sized papers

Short and long consecutive pairs model in the interpretation of MFE and F-ODMR experiments in molecular crystals

International audienceWe have presented a model of two consecutive pairs of triplet excitons, which consists of a succession of two pairs known as short pair and long pair with reference to their respective lifetimes. We have applied this model to the modulation of prompt fluorescence (PF) in crystalline tetracene by a static magnetic field (MFE) and a microwave field (F-ODMR). The two types of experiments have been enough perfectly reproduced by using the same set of kinetics constants. Thus, we have arrived to rise the inconsistencies which one reproached the Seventies kinetic model