Academic literature on the topic 'Nitroso-glutathione'

We aimed to investigate the effects of two nitric oxide donors in acute inflammation in rats. The experiment was carried out on white Wistar rats, randomly distributed in 4 groups of 5 animals each; the substances were administered intraperitoneally as follows: Group 1 (SS): saline solution 0.1mL/100 g body weight (control); Group 2 (IND): indometacin 150 mg/kg body weight; Group 3 (NEB): nebivolol 1 mg/kg body weight; Group 4 (GSNO): S-nitroso-glutathione 1 mg/kg body weight. An experimental model of acute hind paw inflammation with carrageenan was used for the researches. The influence of the nitric oxide donors on blood parameters, specific inflammatory and immune markers was evaluated 24 h, respectively 72 hours after the injection of irritant agent. The experimental protocol was implemented according to the recommendations of our University Committee for Research and Ethical Issues. The administration of nitric oxide donors nebivolol and S-nitroso-glutathione was accompanied by a substantial diminution of paw edema, as well as by an important decrease in the percent of lymphocytes, a reduction of interleukin 6 and tumor necrosis factor alpha values. The effects of nebivolol were more accentuated than of S-nitroso-glutathione, but less intense than of indomethacin in the experiment. The treatment with nebivolol and S-nitroso-glutathione produced anti-inflammatory effects on local acute inflammation in the carrageenan-induced paw edema test in rats.

We aimed to investigate the influence of two nitric oxide donors on the oxidative stress and the liver function in rats with experimental-induced acute paw inflammation.The experiment was carried out on white male Wistar rats (200-250 g), randomly assigned into 4 groups of 5 animals each, which received the substances intraperitoneal, as follows: group 1 (Control) saline solution 0.1 ml/100 g body weight; group 2 (IND) indomethacin 150 mg/kg body weight (kbw); groups 3 (NEB) and 4 (GSNO) nebivolol 1 mg/kbw, respectively S-nitroso-glutathione 1 mg/kbw. Carrageenan-induced rat�s paw edema test was used for the generation of acute inflammation. The activity of liver enzymes and of some antioxidant parameters was evaluated before the carrageenan injection, after 24 hours and 3 days. The experimental protocol was approved by the University�s Ethic Committee on Research and Ethical Issues.The administration of indomethacin, nebivolol and S-nitroso-glutathione appears to decrease the oxidative stress after 24 h in rats with experimental-induced acute paw inflammation. The nitric oxide donors nebivolol and S-nitroso-glutathione produced moderate functional and structural liver disturbances in rats with acute inflammation.

S-Nitrosation is a post-translational modification of protein cysteine residues, which occurs in response to cellular oxidative stress. Although it is increasingly being linked to physiologically important processes, the molecular basis for protein regulation by this modification remains poorly understood. Biophysical methods were used to elucidate the mechanism and molecular consequences of S-nitrosation of glutathione transferase (GST) P1-1, a ubiquitous homodimeric detoxification enzyme and important target for cancer therapeutics. Transient kinetic techniques, isothermal titration calorimetry and protein engineering were used to develop a minimal mechanism for S-nitrosation of GSTP1-1, the first for any protein. Cys47 of GSTP1-1 is S-nitrosated according to a conformational selection mechanism, with the chemical step limited by a pre-equilibrium between the open and closed conformations of a dynamic helix at the active site. Cys101, in contrast, is Snitrosated in a single step but is subject to negative cooperativity due to steric hindrance at the dimer interface. S-Nitrosation at Cys47 and Cys101 was found to reduce the detoxification activity of GSTP1-1 by 94%. Circular dichroism spectroscopy, acrylamide quenching and amide hydrogen-deuterium exchange mass spectrometry experiments revealed that the loss of activity is due to the introduction of local disorder at the active site. Furthermore, the modification destabilises domain 1 of GSTP1-1 against denaturation, smoothing the unfolding energy landscape of the protein and introducing a refolding defect. These data elucidate the physical basis for the regulation of GSTP1-1 by S-nitrosation, and provide general insight into the mechanism of S-nitrosation and its effect protein stability and dynamics.

It is becoming increasingly evident that redox state leading to post-translational modifications of structural proteins, enzymes and ion channels can cause activation or inhibition of cellular function (Andrade et al., 1998a, Jackson, 2008, Kelly et al., 1996). While low levels of nitric oxide (NO) synthesised by endothelial and neuronal nitric oxide synthase have been shown to provide a beneficial effect to tissues, the elevated release of NO accompanying inflammation has a detrimental effect, resulting in dysfunction (Khanna et al., 2005). We investigated the functional consequence and molecular substrate of NO and another potentially harmful reactive oxygen species, H ₂O ₂, on the skeletal muscle myofilament. In a rat model we used functional myography of demembranated single fast- and slow-twitch skeletal muscle fibers to examined the consequence of the addition of the free radical NO and reactive oxygen species H₂O₂ on the Ca²⁺ sensitivity of the myofilament. The reversibility of oxidative modifications following NO or H ₂O ₂ treatment was examined using the general anti-oxidant dithiothreitol. Isoelectric focusing combined with SDS-PAGE separation of proteins investigated the post-translational modification of free-radical exposed myofilament proteins. Molecular substitution of endogenous troponin C (TnC) with WT cardiac/slow TnC or C84S TnC, incapable of being oxidized at Cys84, investigated the molecular and functional consequence of oxidation of TnC at Cys84. Exposure of fast-twitch muscle fibers to NO resulted in a decrease in Ca²⁺ sensitivity, while H ₂O ₂ had the opposite effect, increasing Ca²⁺ sensitivity. In contrast, slow-twitch fibers were insensitive to both NO and H ₂O ₂. Following myofilament exposure to NO (~2 uM) proteomic analysis revealed that many proteins underwent post-translational modification, including myosin light chain (LC ₂₀) and TnC. Molecular substitution of endogenous fast-twitch TnC with WT-cardiac/slow TnC demonstrated a similar sensitivity to NO as WT skeletal muscle. In contrast TnC, non-oxidizable at Cys84, rendered fast-twitch skeletal muscle insensitive to NO. Many myofilament proteins, including myosin light chains were identified as being post-translationally modified by NO exposure, however, molecular substitution experiments clearly identify TnC, specifically residue Cys84 as the functional substrate responsible for fast-twitch skeletal muscle sensitivity to NO. Although slow-twitch muscle contains the same isoform of TnC, it was insensitive to NO. This suggests that slow-twitch muscle may have a greater capacity for anti-oxidant defense than fast-twitch muscle. The contrasting increase in Ca²⁺ sensitivity following H ₂O ₂ to the decline caused by NO demonstrates that not all oxidative molecules act alike, possibly targeting differing substrates and causing differing post-translational modifications.
Thesis (Ph.D.) -- University of Adelaide, School of Medical Sciences, 2011