323 research outputs found

    Peroxynitrite-mediated oxidation of the C85S/C152E mutant of dihydrofolate reductase from Escherichia coli: functional and structural effects

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    Peroxynitrite is a potent reactive oxygen species that is believed to mediate deleterious protein modifications in a wide variety of neurodegenerative disorders. In this study, we have analysed the effects of oxidative damage induced by peroxynitrite on a cysteine-free mutant of dihydrofolate reductase (SE-DHFR), from a functional and a structural point of view. The peroxynitrite-mediated oxidation results in the inhibition, concentration-dependent, of the catalytic activity. This effect is strongly influenced by the HCO(3)(-)/CO(2) buffering system, that we observed to significantly affect the yield of protein oxidation by modulating the peroxynitrite-induced modification of aromatic residues. Because of this effect, in presence of bicarbonate system, we have observed a protection of enzymatic activity of SE-DHFR with regard to peroxynitrite. The thermodynamic stability of the oxidized protein has been studied in comparison with the non-oxidized protein by differential scanning calorimetry. The thermodynamic parameters obtained showed a decrease of stability of SE-DHFR upon oxidation, evaluated in terms of Gibbs free energy of about 1.25 kcal/mol at 25 degrees C, with respect to the non-oxidized protein. Together, these data indicate that structural and functional alterations induced by peroxynitrite may play a direct role in compromising DHFR function in multiple pathological conditions

    Effect of Integration of Linseed and Vitamin E in Charolaise × Podolica Bulls’ Diet on Fatty Acids Profile, Beef Color and Lipid Stability

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    Dietary supplementation with oilseeds improves the fatty acid profiles of meat, but results are often inconsistent. This study aimed to assess the effects of dietary linseed and vitamin E supplementation on fatty acid profile, cholesterol content and color stability of beef samples. Dorsal subcutaneous fat samples were subjected to lipid stability assessment. Eighteen young bulls (385 ± 15 kg BW, age 8–9 months) were allocated into three homogeneous groups, each receiving ad libitum wheat straw and concentrate only (CON = 5.5 kg/day), concentrate with linseed (LIN = 80 g/kg, i.e., 440 g/head/day), and concentrate with linseed plus vitamin E (L + E = 80 g/kg, i.e., 440 g/head/day + 2500 IU/head/day of Vitamin E). Group L+E showed significantly lower cholesterol content, lower n-6/n-3 ratio and a higher PUFA percentage compared to the CON group. Meat color was affected by feeding LIN with a decrease in a*, b*, and C* compared to the CON group. The experimental diets increased H◦ values compared to the CON group. A positive effect of vitamin E in protecting lipids of dorsal subcutaneous depots from oxidation was detected in group L+E compared to group LIN. The supplementation with extruded linseeds in the diet had positive effects on the nutritional profile of the meat. When vitamin E was included, linseed did not alter the color of meat, and the lipid stability of the subcutaneous fat improved

    Analisi di settore: i discount in Europa

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    Indice: Definizione del business - Analisi del macroambiente - Analisi della domanda - Analisi dell'offerta - Prospettive e tendenze competitiv

    Mechanism of inhibition of wt-dihydrofolate reductase from E. coli by tea epigallocatechin-gallate.

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    Hydroxy-3-methyl-glutaryl-CoA reductase (HMGR) is the rate-controlling enzyme of cholesterol synthesis, and owing to its biological and pharmacological relevance, researchers have investigated several compounds capable of modulating its activity with the hope of developing new hypocholesterolemic drugs. In particular, polyphenol-rich extracts were extensively tested for their cholesterol-lowering effect as alternatives, or adjuvants, to the conventional statin therapies, but a full understanding of the mechanism of their action has yet to be reached. Our work reports on a detailed kinetic and equilibrium study on the modulation of HMGR by the most-abundant catechin in green tea, epigallocatechin-3-gallate (EGCG). Using a concerted approach involving spectrophotometric, optical biosensor, and chromatographic analyses, molecular docking, and site-directed mutagenesis on the cofactor site of HMGR, we have demonstrated that EGCG potently inhibits the in vitro activity of HMGR (K(i) in the nanomolar range) by competitively binding to the cofactor site of the reductase. Finally, we evaluated the effect of combined EGCG-statin administration
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