New insights regarding HCV-NS5A structure/function and indication of genotypic differences

<p>Abstract</p> <p>Background</p> <p>HCV is prevalent throughout the world. It is a major cause of chronic liver disease. There is no effective vaccine and the most common therapy, based on Peginterferon, has a success rate of ~50%. The mechanisms underlying viral resistance have not been elucidated but it has been suggested that both host and virus contribute to therapy outcome. Non-structural 5A (NS5A) protein, a critical virus component, is involved in cellular and viral processes.</p> <p>Methods</p> <p>The present study analyzed structural and functional features of 345 sequences of HCV-NS5A genotypes 1 or 3, using <it>in silico </it>tools.</p> <p>Results</p> <p>There was residue type composition and secondary structure differences between the genotypes. In addition, second structural variance were statistical different for each response group in genotype 3. A motif search indicated conserved glycosylation, phosphorylation and myristoylation sites that could be important in structural stabilization and function. Furthermore, a highly conserved integrin ligation site was identified, and could be linked to nuclear forms of NS5A. ProtFun indicated NS5A to have diverse enzymatic and nonenzymatic activities, participating in a great range of cell functions, with statistical difference between genotypes.</p> <p>Conclusion</p> <p>This study presents new insights into the HCV-NS5A. It is the first study that using bioinformatics tools, suggests differences between genotypes and response to therapy that can be related to NS5A protein features. Therefore, it emphasizes the importance of using bioinformatics tools in viral studies. Data acquired herein will aid in clarifying the structure/function of this protein and in the development of antiviral agents.</p

Models and measurements of energy-dependent quenching

Energy-dependent quenching (qE) in photosystem II (PSII) is a pH-dependent response that enables plants to regulate light harvesting in response to rapid fluctuations in light intensity. In this review, we aim to provide a physical picture for understanding the interplay between the triggering of qE by a pH gradient across the thylakoid membrane and subsequent changes in PSII. We discuss how these changes alter the energy transfer network of chlorophyll in the grana membrane and allow it to switch between an unquenched and quenched state. Within this conceptual framework, we describe the biochemical and spectroscopic measurements and models that have been used to understand the mechanism of qE in plants with a focus on measurements of samples that perform qE in response to light. In addition, we address the outstanding questions and challenges in the field. One of the current challenges in gaining a full understanding of qE is the difficulty in simultaneously measuring both the photophysical mechanism of quenching and the physiological state of the thylakoid membrane. We suggest that new experimental and modeling efforts that can monitor the many processes that occur on multiple timescales and length scales will be important for elucidating the quantitative details of the mechanism of qE

Evaluation of the 2-thiobarbituric acid method for the measurement of lipid oxidation in mechanically deboned gamma irradiated chicken meat

This study evaluated the 2-thiobarbituric acid (TBA) method for the measurement of lipid oxidation in samples of mechanically deboned chicken meat (MDCM), both gamma-irradiated with doses of 4.0 and 5.0 kGy and non-irradiated. The values for the percent recuperation of 1, 1,3,3-tetraethoxy-propane (TEP) and for the conversion factor K, for the samples irradiated with doses of 4.0 and 5.0 kGy and the non-irradiated samples, were, respectively, 88.6, 90.0 and 88.6% for the former and 4.98, 4.91 and 4.98 for K. Comparing the results obtained for the samples of MDCM irradiated with doses of 4.0 and 5.0 kGy and the non-irradiated samples, as evaluated by the TBA distillation method, it was observed that the values for percent recuperation of TEP, the values for K and the spectral curves, as also the linear equations of the standard curves for the distillation of malonaldehyde, were similar for all the samples, no specific interference in the TBA test, due to the process of irradiating the MDCM, being detected. (C) 2002 Elsevier Science Ltd. All rights reserved.80343343