Biography:

In the past Laura Castro has collaborated on articles with José M. Souza and Santiago Mansilla. One of their most recent publications is Cytochrome c: a catalyst and target of nitrite-hydrogen peroxide-dependent protein nitration. Which was published in journal Archives of Biochemistry and Biophysics.

More information about Laura Castro research including statistics on their citations can be found on their Copernicus Academic profile page.

Laura Castro's Articles: (7)

Cytochrome c: a catalyst and target of nitrite-hydrogen peroxide-dependent protein nitration

AbstractNitration of protein tyrosine residues to 3-nitrotyrosine (NO2Tyr) serves as both a marker and mediator of pathogenic reactions of nitric oxide (NO), with peroxynitrite (ONOO−) and leukocyte peroxidase-derived nitrogen dioxide (NO2) being proximal mediators of nitration reactions in vivo. Cytochrome c is a respiratory and apoptotic signaling heme protein localized exofacially on the inner mitochondrial membrane. We report herein a novel function for cytochrome c as a catalyst for nitrite (NO2−) and hydrogen peroxide (H2O2)-mediated nitration reactions. Cytochrome c catalyzes both self- and adjacent-molecule (hydroxyphenylacetic acid, Mn-superoxide dismutase) nitration via heme-dependent mechanisms involving tyrosyl radical and NO2 production, as for phagocyte peroxidases. Although low molecular weight phenolic nitration yields were similar for cytochrome c and the proteolytic fragment of cytochrome c microperoxidase-11 (MPx-11), greater extents of protein nitration occurred when MPx-11 served as catalyst. Partial proteolysis of cytochrome c increased both the peroxidase and nitrating activities of cytochrome c. Extensive tyrosine nitration of Mn-superoxide dismutase occurred when exposed to either cytochrome c or MPx-11 in the presence of H2O2 and NO2−, with no apparent decrease in catalytic activity. These results reveal a post-translational tyrosine modification mechanism that is mediated by an abundant hemoprotein present in both mitochondrial and cytosolic compartments. The data also infer that the distribution of specific proteins capable of serving as potent catalysts of nitration can lend both spatial and molecular specificity to biomolecule nitration reactions.

Regular ArticleModulatory Role of Nitric Oxide on Superoxide-Dependent Luminol Chemiluminescence

AbstractReactive oxygen species are involved in luminol chemiexcitation induced in biological systems, but the contribution of nitrogen-derived oxidants in the process still remains unclear. Herein, we report that luminol chemiluminescence (LCL) induced by a superoxide[formula]- and hydrogen peroxide (H2O2)-generating system (2–25 mU/ml xanthine oxidase plus acetaldehyde and oxygen) was markedly inhibited by nitric oxide ([formula]NO) added either as bolus (0–10 μm) or a continuous flow (0–10 μm/min). However, the inhibition of LCL was followed by an overshoot in light emission after most[formula]NO was consumed or the infusion stopped and was due to reactions of remaining peroxynitrite, the product of the reaction between[formula]and[formula]NO, with luminol. Nitric oxide also inhibited peroxynitrite- and glucose oxidase-induced LCL, but no overshoot was observed. On the other hand, a continuous flux of pure peroxynitrite, at 2 to 10 μm/min, induced LCL with quantum yields close to those obtained by identical micromolar fluxes of[formula], while peroxynitrite formed from the decomposition of the sydnonimine SIN-1 yielded 76% of the chemiluminescence obtained with authentic peroxynitrite. Peroxynitrite- induced LCL was 80 and 55% inhibitable by SOD and catalase, respectively, showing that there were[formula]and H2O2-dependent routes of chemiexcitation. The hydroxyl radical scavengers dimethyl sulfoxide, mannitol, and ethanol and the metal chelator diethylenetriaminepentaacetic acid did not inhibit peroxynitrite-induced LCL while desferrioxamine was an efficient inhibitor of light emission by reaction with an activated state of peroxynitrous acid which is responsible of performing the initial one-electron oxidation of luminol. Our results are consistent with a dual role of[formula]NO in[formula]-induced LCL: (I) formation of peroxynitrite which in turn promotes the light-emitting route and (II) reaction with luminol radical intermediates directing the system toward a dark pathway. These considerations are of critical importance when analyzing cell- and tissue-derived LCL in[formula]NO-,[formula]-, and peroxynitrite-producing systems.

Biosorption of Zn(II) from industrial effluents using sugar beet pulp and F. vesiculosus: From laboratory tests to a pilot approach

Highlights•Industrial wastewaters can be treated with F. vesiculosus and sugar beet pulp.•F. vesiculosus showed higher sorption capacity than sugar beet pulp.•Wastewaters can be treated in column and serial columns increased the service life.•The scaling-up allowed the decontamination of higher volumes of dissolution.•The mixture of biomasses improved the performance of the columns reducing costs.

Chapter Eleven - Nitrocytochrome c: Synthesis, Purification, and Functional Studies

AbstractPosttranslational protein tyrosine oxidation, to yield 3-nitrotyrosine, is a biologically relevant protein modification related with acute and chronic inflammation and degenerative processes. It is usually associated with a decrease or loss in protein function. However, in some proteins, tyrosine nitration results in an increase or gain in protein function. Nitration of cytochrome c by biological oxidants in vitro can be achieved via different mechanisms, which include reactions with peroxynitrite, nitrite plus hydrogen peroxide, and nitric oxide plus hydrogen peroxide, and result in a loss in its electron transport capacity and in a higher peroxidatic activity. This chapter describes the methodology for studying chemical and biological properties of nitrocytochrome c. In particular, we report methods to synthesize tyrosine-nitrated cytochrome c, purify cytochrome c mononitrated species, map the sites of tyrosine nitration, and investigate the functional consequences of nitrated cytochrome c on mitochondrial electron transport properties, peroxidatic activity, and apoptosome assembly.

Heavy metal adsorption using biogenic iron compounds

Highlights•The natural consortium produced mainly siderite and magnetite.•Biogenic iron compounds can be used as adsorbents for heavy metals.•Biogenic compounds showed a higher uptake of As and Cr.•Zinc and copper were adsorbed by the organic matter bound to nanoparticles.•Other metals in solution affected the uptake compared to the monometallic systems.

200 - Biochemical and structural characterization of human aconitase, a key mitochondrial oxidant target

Mitochondrial aconitase (m-aconitase), an essential enzyme that catalyzes the reversible isomerization of citrate to isocitrate in the TCA cycle, is very sensitive to reactive oxygen and nitrogen species due to its particularly labile [4Fe-4S] prosthetic group which yields an inactive [3Fe-4S] cluster upon oxidation. Several cell and animal studies revealed m-aconitase as a main oxidant target during ageing and in pathologies in which mitochondrial dysfunction is implied. Other post-translational modifications have been reported such as nitration, succinylation, acetylation, phosphorylation and glutathionylation. In order to characterize how post-translational modifications of human (h) m-aconitase would impact in mitochondrial structure and function, we designed and expressed a recombinant hm-aconitase with a His-tag on its N-terminus. We obtained a high yield of pure (≥99%) enzyme of 83.002 ± 40 Da in agreement with the theorical molecular weight. The predicted structure of the hm-aconitase was build based on the Sus scrofa heart aconitase from the PDB database as both proteins share a 97% of identity. Hm-aconitase exhibits a specific activity of 22 ± 2 U/mg after being activated with 50 µM Fe2+ and 10 mM DTT during 90 minutes under argon saturated atmosphere. Kinetic characterization of hm-aconitase yields KM of 950 ± 60, 80 ± 10 and 8.0 ± 0.7 µM for citrate, isocitrate and cis-aconitate respectively. Peroxynitrite and H2O2 reacted with hm-aconitase with second rate order constants of 105 M-1 s-1 and 102 M-1 s-1, respectively as previously reported for other mammalian aconitases, yielding a [3Fe-4S] reactivable enzyme. Thermal denaturation assessed by Trp fluorescence of hm-aconitase resulted in melting temperatures of 51.1 ± 0.5 and 43.6 ± 0.2 ºC for [4Fe-4S] and [3Fe-4S] forms of hm-aconitase, sustaining lower enzyme stability upon cluster oxidation while addition of substrate or inhibitors modified the unfolding mechanism of the active enzyme.

Aeromonas hydrophila produces conductive nanowires

AbstractAeromonas hydrophila is a facultative anaerobe which, under conditions of oxygen depletion, uses Fe(III) as electron acceptor. A. hydrophila produces pili during growth with Fe(III). The study was focused on the characterization of the morphology, the electrical properties and the nature of the bacterial pili. Scanning electron microscopy and conductive-probe atomic force microscopy revealed the presence of filaments between cells and substrate and their conductive nature. Our results indicate that pili of A. hydrophila strain A might serve as biological nanowires, transferring electrons from the cell surface to the surface of Fe(III) oxides and, in addition, the possibility of playing a role in inter/intra species signaling. Quorum sensing (QS) is recognized as one of the main regulatory ways for extracellular polymeric substances (EPS) production and biofilm formation. We present evidence that nanowire formation can be regulated by addition of synthetic acyl-homoserine lactones (AHL). These conductive pili may be involved in various interactions, and their protein components might be usable in the future for biotechnological approaches in materials science.

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