1,721,455 research outputs found
Peroxynitrite Detoxification by Human Haptoglobin:Hemoglobin Complexes: A Comparative Study.
No full textHaptoglobin (Hp) reacts with dimeric hemoglobin (Hb), shifts the equilibrium in favor of the αβ dimer and displays heme-based catalysis. Here, kinetics of peroxynitrite scavenging by ferric human haptoglobin1-1:hemoglobin and haptoglobin2-2:hemoglobin complexes (Hp1-1:Hb(III) and Hp2-2:Hb(III), respectively) is reported between pH 6.2 and 8.3 at 20.0 °C. The reactivity of Hp1-1:Hb(III) and Hp2-2:Hb(III) against peroxynitrite is similar to that of tetrameric Hb(III), reflecting the R-like structure of the αβ dimers of Hb(III) bound to Hp. To investigate the protective role of Hp1-1:Hb(III) and Hp2-2:Hb(III) against peroxynitrite-mediated nitration, the relative yield of nitro-l-tyrosine formed by the reaction of peroxynitrite with free l-tyrosine was determined. Interestingly, both Hp1-1:Hb(III) and Hp2-2:Hb(III) impair peroxynitrite-mediated nitration of free l-tyrosine. Therefore, Hp:Hb complexes could participate to the detoxification of reactive nitrogen and oxygen species in vivo, contributing to prevent extra-erythrocytic Hb-induced damage during hemolytic crisis
Experimental tests about the cooling/freezing of the molten salts in the receiver tubes of a solar power plant with parabolic trough
No full textIn 2003 ENEA realized the PCS experimental Facility at Casaccia Research Centre (Rome, Italy), in order to test in real operating conditions the components of a parabolic trough solar plant, and to evaluate the technical feasibility of using the solar molten salts mixture (60% NaNO3, 40% KNO3, melting point 220÷240°C) in such a type of plant. ENEA also had the need to assess the behaviour of the solar receiver tubes during abnormal operating situations (wrong operation, pump block, power failure, etc.), when a block of the circulation of the molten salts may occur and cause the cooling or, worse, the freezing of the salts mixture inside the pipes. Some experimental tests have been performed, aimed to examine what happens in such a cases. In fact, without quick maneuvers to restart the circulation of the molten salts or to readily empty the receiver tubes, the molten salts contained in them may cool down to temperatures near/below the solidification. In this report are shown the results of the experimental tests carried out on the receiver tubes of the PCS Facility by cooling the process fluid down to temperatures near or below its freezing point. The tests show that the solidification of the salts does not damage the components of the plant but it is manageable and reversible, provided you apply the correct procedures. © 2017 Author(s)
Steroid hormone rapid signaling: the pivotal role of S-palmitoylation
No full textNuclear receptors (NRs) comprise a large family of proteins essential to manipulate various aspects of human biology. The class III of the NR family includes steroid hormone receptors (SHRs) involved in embryonic development, maintenance of differentiated cellular phenotypes, metabolism, and cell death. Dysfunction of SHR signaling leads to proliferative, reproductive, and metabolic diseases. SHRs are ligand-activated transcription factors which regulate cellular processes by inducing genomic events. In addition, membrane-initiating non-genomic signals have been described for several SHRs. These non-genomic actions are independent of the SHR transcription activity and have been attributed to canonical SHRs and non-canonical hormone binding sites located at the plasma membrane. The molecular bases for SHR-plasma membrane association represent a debated issue. Here, we hypothesize that the SHR amino acid sequence homologous to that encompassing the S-palmitoylated Cys447 residue of human estrogen receptor alpha could represent a new consensus sequence for SHR S-palmitoylation. Reversible S-palmitoylation of SHRs could play a critical role in receptor localization at the plasma membrane and in rapid nongenomic signaling activation
Abacavir modulates peroxynitrite-mediated oxidation of ferrous nitrosylated human serum heme-albumin
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Membrane association of estrogen receptor α and beta influences 17beta-estradiol-mediated cancer cell proliferation
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