236 research outputs found
Isolation of an active and heat-stable monomeric form of Cu,Zn superoxide dismutase from the periplasmic space of Escherichia coli
No full textWe have purified the Cu,Zn superoxide dismutase (CuZnSOD) from the periplasmic space of an Escherichia coli strain unable to synthesize MnSOD and FeSOD. Gel filtration chromatography evidenced that under all the experimental conditions tested the enzyme was monomeric. The catalytic activity of this CuZnSOD was comparable to that of other well characterized dimeric eukaryotic isoenzymes, indicating that a dimeric structure is not essential to ensure enzymatic efficiency. Furthermore the purified enzyme proved to be highly heat-stable and, uniquely among CuZnSODs, protease-sensitive. The latter property may explain the previously described lability of this protein in cell extracts
Structural modification and bioavailability of starch components as related to the extent of Maillard reaction: An enzymatic degradation and a solid-state C-13 CPMAS NMR Study
No full textStarch and starch components, amylose and amylopectin, from potato, have been studied in order to understand the modifications, induced by different levels of the Maillard reaction occurring in the presence of amino acids (L-lysine in this study), in the macromolecular structure and digestibility. Structural characterization was performed by C-13 CPMAS NMR, and differences in the bioavailability of these polymers were studied by enzymatic degradation kinetics. Results obtained reveal that changes are induced by the Maillard reaction, whose occurrence has been verified and measured by the furosine (epsilon-N-2-furoylmethyl-L-lysine) evaluation, on the macromolecular structure of starchy materials and on their enzymatic susceptibility. Lysine seems to act as a disordering agent; a loss of crystallinity is evident for starch and amylopectin and, in particular, for amylose. Finally, within the same sample, as the lysine concentration increases, the polymer digestibility decreases, confirming that structural organization is not the only determinant of starch digestibility
Copper-dependent toxicity in SH-SY5Y neuroblasoma cells involves mitochondrial damage.
No full textTreatment of SH-SY5Y human neuroblastoma cells with copper sulphate (50-300microM) in complete medium for 24h caused an increase in the level of the metal both in whole cells and in isolated mitoplasts. Toxic effects of copper resulted in the impairment of the capability of mitochondrial dehydrogenases to reduce a tetrazolium salt, and, to a lesser extent, in the loss of the integrity of the plasma membrane. The mechanism of toxicity involved the production of reactive oxygen species, amplified by the presence of ascorbate. Decreases in the levels of several mitochondrial proteins (subunits of complex I, complex V, and of the pyruvate dehydrogenase complex) were observed. These findings demonstrate that mitochondria are an early and susceptible target of copper-mediated oxidative stress in neuronal cells and support the hypothesis that mitochondrial damage triggers the neurodegenerative processes associated with copper overload in Wilson's disease
Copper-dependent metabolism of Cu,Zn-superoxide dismutase in human K562 cells. Lack of specific transcriptional activation and accumulation of a partially inactivated enzyme
No full textThe regulation of Cu,Zn-superoxide dismutase by copper was investigated in human K562 cells. Copper ions caused a dose- and time-dependent increase, up to 3-fold, of the steady-state level of Cu,Zu-superoxide dismutase mRNA. A comparable increase was also observed for actin and ribosomal protein L32 mRNAs, but not for metallothionein mRNA which was augmented more than 50-fold and showed a different induction pattern. The copper-induced mRNAs were actively translated as judged from their enhanced loading on polysomes, the concomitantly increased cellular protein levels and an augmented incorporation of [3H]lysine into acid-precipitable material. Cu,Zn-superoxide dismutase protein followed this general trend, as demonstrated by dose- and time-dependent increases in immunoreactive and enzymically active protein. However, a specific accumulation of Cu,Zn-superoxide dismutase was noticed in cells grown in the presence of copper, that was not detectable for other proteins. Purification of the enzyme demonstrated that Cu,Zn-superoxide dismutase was present as a reconstitutable, copper-deficient protein with high specific activity (kcat./Cu = 0.89 x 10(9) M-1.s-1) in untreated K562 cells and as a fully metallated protein with low specific activity (kcat./Cu = 0.54 x 10(9) M-1.s-1) in copper-treated cells. Pulse-chase experiments using [3H]lysine indicated that turnover rates of Cu,Zn-superoxide dismutase in K562 cells were not affected by growth in copper-enriched medium, whereas turnover of total protein was significantly enhanced as a function of metal supplementation. From these results we conclude that: (i) unlike in yeast [Carrì, Galiazzo, Ciriolo and Rotilio (1991) FEBS Lett. 278, 263-266] Cu,Zn-superoxide dismutase is not specifically regulated by copper at the transcriptional level in human K562 cells, suggesting that this type of regulation has not been conserved during the evolution of higher eukaryotes; (ii) copper ions cause an inactivation of the enzyme in intact K562 cells; and (iii) the metabolic stability of Cu,Zn-superoxide dismutase results in its relative accumulation under conditions that lead to increased protein turnover
Glutathione disulfide induces apoptosis in U937 cells by a redox-mediated p38 MAP kinase pathway.
No full textChanges in the intracellular reduced/oxidized glutathione ratio (GSH/GSSG) are crucial reduction-oxidation (redox) events that trigger downstream proliferation or death responses. We investigated the molecular mechanisms underlying redox-mediated cell signaling upon an oxidative insult by treating U937 cells with exogenous nonpermeable GSSG. This treatment results in a significant decrease of exofacial cell membrane thiol groups and intracellular decrement of GSH content, owing to its engagement in the formation of mixed disulfides. Changes in thioredoxin redox state were also observed, and they may be related to the activation of upstream ASK1 and selective induction of downstream p38 mitogen-activated protein kinase (MAPK) pathway, detectable by phosphorylation of MKK3/6 and p38 MAPK. Moreover, an increase in reactive oxygen species production was detected, and cells were committed to apoptosis along the mitochondrial pathway, evidenced by Bcl-2 down-regulation, cytochome c release from mitochondria, caspase-9 cleavage, and caspase-3 activation. GSH ethyl ester, a precursor of GSH, by counteracting intracellular mixed disulfide formation, canceled both p38 MAPK activation and GSSG-mediated apoptosis via inhibition of thioredoxin oxidation and stabilization of thioredoxin/ASK1 complex, whereas, blockage of p38 MAPK by specific inhibitor SB 203580 allowed apoptosis at a very reduced extent. Results suggest that kinase cascade may serve as a primary transducer of cytoplasmic oxidative signals to the nucleus before apoptosis-inducing signals are activated
Interplay of Cu,Zn superoxide dismutase and nitric oxide synthase in Neurodegenerative processes
No full textReactive oxygen and nitrogen species (ROS and RNS) have been extensively recognized as important signaling molecules implicated in physiological processes such as gene expression, cell differentiation and immune activation. Nevertheless, continuous production of these species may produce oxidative and/or nitrosative stress resulting in cell damage and ultimately leading to cell death. Due to the high oxygen consumption and relative poor antioxidant defense, the central nervous system is highly susceptible to ROS- and RNS-mediated toxicity. Actually, the oxidative and nitrosative stress have been implicated in the pathogenesis of neurodegeneration of a large variety of neurological disorders. This review will cover some aspects of the involvement of ROS- and RNS-mediated apoptotic processes occurring in cellular models of familial amyotrophic lateral sclerosis (FALS), in particular the cases associated with mutations in SOD1, the gene encoding Cu,Zn superoxide dismutase (Cu,Zn SOD). A possible role for proteasome in the inhibition of neurodegenerative process by balancing ROS and RNS species is envisaged on the basis of evidence provided by results obtained from studies on this experimental model
In vivo formation of Cu,Zn superoxide dismutase disulfide bond in Escherichia coli
No full textAbstractWe have found that the in vivo folding of periplasmic Escherichia coli Cu,Zn superoxide dismutase is assisted by DsbA, which catalyzes the efficient formation of its single disulfide bond, whose integrity is essential to ensure full catalytic activity to the enzyme. In line with these findings, we also report that the production of recombinant Xenopus laevis Cu,Zn superoxide dismutase is enhanced when the enzyme is exported in the periplasmic space or is expressed in thioredoxin reductase mutant strains. Our data show that inefficient disulfide bond oxidation in the bacterial cytoplasm inhibits Cu,Zn superoxide dismutase folding in this cellular compartment
Cell signalling and the glutathione redox system
No full textThe reduction/oxidation (redox) state of the cell is a consequence of the balance between the levels of oxidising and reducing equivalents. A reducing intracellular environment is often associated with cell survival; however, redox unbalance is necessary since it represents a regulatory sensor for several nuclear transcription factors. Activator protein 1 (AP-1), nuclear factor-κB (NF-κB) and protein tyrosine phosphatases 1-B (PTP-1B) are some of the well-known molecular factors for which a redox modulation of their activity has been demonstrated. The glutathione buffer system modulates cell response to redox changes induced by either external or intracellular stimuli. This paper summarises recent knowledge on the role played by several redox modulators in inducing signalling events that finally regulate cell cycle progression. © 2002 Elsevier Science Inc. All rights reserved
Molecular transduction mechanisms of the redox network underlying the antiproliferative effects of allyl compounds from garlic
No full textSecondary Raw Materials for Circular Economy in Construction Sector: A Review
No full textConstruction and demolition waste (CDW) is very high in quantity, 30% - 40% of total
solid waste and their management is inadequate and lack the integration of sustainability concepts.
This situation leads to severe environmental effects, which are mainly associated with the
production of new building materials due to the low recovery rate. In fact some studies show that 5-
10% of total energy consumption across the EU is related to the manufacture of construction
products. For this reason, CDW is a priority for many policies globally. For several years, a
growing trend towards more sustainable construction processes has been taking place with a focus
on secondary raw materials with lower environmental impacts on the entire life cycle. For this
reason, this paper intends to contribute to increasing knowledge in this field through a review
article. The review has the aim to evaluate the research gap, strategies to reduce construction waste
and to promote the recycled materials use for a circular economy in construction sector.
The results of the study showed that interest in this field of research has grown strongly over the
years: the most publications on the subject relate to the last five years. On the other hand, issues
relating to the topic did not attract particular interest in the range 2010-2016, in fact the number of
publications in this period did not exceed 4%.
The research showed that Europe is among the communities most sensitive to the issue and it has
clearly revealed that there are still many barriers and research gaps to be overcome on this issue and
the study has tried to identify the main ones
- …
