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941.
Enhanced hydroxyl radical production by dihydroxybenzene-driven Fenton reactions: implications for wood biodegradation 总被引:1,自引:0,他引:1
David Contreras Jaime Rodríguez Juanita Freer Brigitte Schwederski Wolfgang Kaim 《Journal of biological inorganic chemistry》2007,12(7):1055-1061
Brown rot fungi degrade wood, in initial stages, mainly through hydroxyl radicals (•OH) produced by Fenton reactions. These
Fenton reactions can be promoted by dihydroxybenzenes (DHBs), which can chelate and reduce Fe(III), increasing the reactivity
for different substrates. This mechanism allows the extensive degradation of carbohydrates and the oxidation of lignin during
wood biodegradation by brown rot fungi. To understand the enhanced reactivity in these systems, kinetics experiments were
carried out, measuring •OH formation by the spin-trapping technique of electron paramagnetic resonance spectroscopy. As models
of the fungal DHBs, 1,2-dihydroxybenzene (catechol), 2,3-dihydroxybenzoic acid and 3,4-dihydroxybenzoic acid were utilized
as well as 1,2-dihydroxy-3,5-benzenedisulfonate as a non-Fe(III)-reducing substance for comparison. Higher amounts and maintained
concentrations of •OH were observed in the driven Fenton reactions versus the unmodified Fenton process. A linear correlation
between the logarithms of complex stability constants and the •OH production was observed, suggesting participation of such
complexes in the radical production. 相似文献
942.
Shaltouki A Freer M Mei Y Weyman CM 《Apoptosis : an international journal on programmed cell death》2007,12(12):2143-2154
943.
Helicobacter pylori is a Gram-negative bacterium that causes ulcer, atrophic gastritis, adenocarcinoma and mucosa-associated lymphoid tissue lymphoma. Moreover, an ongoing controversial role of this bacterium infection has been suggested in the etiopathogenesis of some extradigestive diseases. The humoral response to H. pylori during a natural infection can be used for diagnostic purposes and as a basis for vaccine development. Host-pathogen interactions may be investigated by means of immunoproteomics, which provides global information about relevant specific and nonspecific antigens, and thus might be suitable to identify novel vaccine candidates or serological markers of H. pylori infection as well as of different related diseases. In this review, we describe how several research groups used H. pylori proteomics combined with western blotting analysis, using sera from patients affected with different H. pylori-related pathologies, to investigate potential associations between host immune response and clinical outcomes of H. pylori infection, resulting in the rapid identification of novel, highly immunoreactive antigens. 相似文献
944.
Gianantonio Battistuzzi Marzia Bellei Christopher Dennison Giulia Di Rocco Katsuko Sato Marco Sola Sachiko Yanagisawa 《Journal of biological inorganic chemistry》2007,12(6):895-900
The thermodynamics of the alkaline transition which influences the spectral and redox properties of the type 1 copper center
in phytocyanins has been determined spectroscopically. The proteins investigated include Rhus vernicifera stellacyanin, cucumber basic protein and its Met89Gln variant, and umecyanin, the stellacyanin from horseradish roots, along
with its Gln95Met variant. The changes in reaction enthalpy and entropy within the protein series show partial compensatory
behavior. Thus, the reaction free energy change (hence the pK
a value) is rather variable. This indicates that species-dependent differences in reaction thermodynamics, although containing
an important contribution from changes in the hydrogen-bonding network of water molecules in the hydration sphere of the protein
(which feature enthalpy–entropy compensation), are to a large extent protein-based. The data for axial ligand variants are
consistent with the hypothesis of a copper-binding His as the deprotonating residue responsible for this transition. 相似文献
945.
946.
Manuel Benedetti Ilaria Verrascina Daniela Pontiggia Federica Locci Benedetta Mattei Giulia De Lorenzo Felice Cervone 《The Plant journal : for cell and molecular biology》2018,94(2):260-273
Recognition of endogenous molecules acting as ‘damage‐associated molecular patterns’ (DAMPs) is a key feature of immunity in both animals and plants. Oligogalacturonides (OGs), i.e. fragments derived from the hydrolysis of homogalacturonan, a major component of pectin are a well known class of DAMPs that activate immunity and protect plants against several microbes. However, hyper‐accumulation of OGs severely affects growth, eventually leading to cell death and clearly pointing to OGs as players in the growth‐defence trade‐off. Here we report a mechanism that may control the homeostasis of OGs avoiding their deleterious hyper‐accumulation. By combining affinity chromatography on acrylamide‐trapped OGs and other procedures, an Arabidopsis thaliana enzyme that specifically oxidizes OGs was purified and identified. The enzyme was named OG OXIDASE 1 (OGOX1) and shown to be encoded by the gene At4g20830. As a typical flavo‐protein, OGOX1 is a sulphite‐sensitive H2O2‐producing enzyme that displays maximal activity on OGs with a degree of polymerization >4. OGOX1 belongs to a large gene family of mainly apoplastic putative FAD‐binding proteins [Berberine Bridge Enzyme‐like (BBE‐like); 27 members], whose biochemical and biological function is largely unexplored. We have found that at least four BBE‐like enzymes in Arabidopsis are OG oxidases (OGOX1–4). Oxidized OGs display a reduced capability of activating the immune responses and are less hydrolysable by fungal polygalacturonases. Plants overexpressing OGOX1 are more resistant to Botrytis cinerea, pointing to a crucial role of OGOX enzymes in plant immunity. 相似文献
947.
948.
Maria Giulia Battelli Massimo Bortolotti Letizia Polito Andrea Bolognesi 《生物化学与生物物理学报:疾病的分子基础》2018,1864(8):2557-2565
Xanthine oxidoreductase (XOR) could contribute to the pathogenesis of metabolic syndrome through the oxidative stress and the inflammatory response induced by XOR-derived reactive oxygen species and uric acid. Hyperuricemia is strongly linked to hypertension, insulin resistance, obesity and hypertriglyceridemia. The serum level of XOR is correlated to triglyceride/high density lipoprotein cholesterol ratio, fasting glycemia, fasting insulinemia and insulin resistance index. Increased activity of endothelium-linked XOR may promote hypertension. In addition, XOR is implicated in pre-adipocyte differentiation and adipogenesis. XOR and uric acid play a role in cell transformation and proliferation as well as in the progression and metastatic process. Collected evidences confirm the contribution of XOR and uric acid in metabolic syndrome. However, in some circumstances XOR and uric acid may have anti-oxidant protective outcomes. The dual-face role of both XOR and uric acid explains the contradictory results obtained with XOR inhibitors and suggests caution in their therapeutic use. 相似文献
949.
Elena Papaleo Giulia Renzetti Gaetano Invernizzi Bjarni Ásgeirsson 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Protein dynamics influence protein function and stability and modulate conformational changes. Such motions depend on the underlying networks of intramolecular interactions and communicating residues within the protein structure. Here, we provide the first characterization of the dynamic fingerprint of the dimeric alkaline phosphatase (AP) from the cold-adapted Vibrio strain G15-21 (VAP), which is among the APs with the highest known kcat at low temperatures.Methods
Multiple all-atom explicit solvent molecular dynamics simulations were employed in conjunction with different metrics to analyze the dynamical patterns and the paths of intra- and intermolecular communication.Results
Interactions and coupled motions at the interface between the two VAP subunits have been characterized, along with the networks of intramolecular interactions. It turns out a low number of intermolecular interactions and coupled motions, which result differently distributed in the two monomers. The paths of long-range communication mediated from the catalytic residues to distal sites were also characterized, pointing out a different information flow in the two subunits.Conclusions
A pattern of asymmetric flexibility is evident in the two identical subunits of the VAP dimer that is intimately linked to a different distribution of intra- and intermolecular interactions. The asymmetry was also evident in pairs of cross-correlated residues during the dynamics.General significance
The results here discussed provide a structural rationale to the half-of-site mechanism previously proposed for VAP and other APs, as well as a general framework to characterize asymmetric dynamics in homomeric enzymes. 相似文献950.