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Ozcan Erel - One of the best experts on this subject based on the ideXlab platform.

  • Thiol/Disulphide Homeostasis, Ischemia Modified Albumin, and Ferroxidase as Oxidative Stress Markers in Women with Obesity with Insulin Resistance.
    Journal of medical biochemistry, 2019
    Co-Authors: Elif Ates, Turan Set, Süleyman Caner Karahan, Cemile Biçer, Ozcan Erel
    Abstract:

    Background: The purpose of the study was to determine oxidative stress-related plasma thiol/disulphide, ischemiamodified albumin (IMA) levels and Ferroxidase activity among women with obesity in insulin-resistant and noninsulin-resistant groups in comparison with an overweight group. Methods: We compared plasma thiol/disulphide, IMA levels, and Ferroxidase activity between the study groups. We analyzed plasma thiol/disulphide homeostasis with a newly developed automated measurement method; IMA with Albumin Cobalt Binding Test and Ferroxidase (ceruloplasmin) levels with an automated, colourimetric method. Results: There were no significant differences between insulin-resistant and non-insulin-resistant women with obesity in terms of plasma native thiol, total thiol, disulphide, disulphide/native thiol ratio, disulphide/total thiol or native thiol/total thiol values. Ferroxidase activity was higher in insulin-resistant than in non-insulin-resistant women with obesity and higher in the total women with obesity group than in the overweight subjects (p

  • thiol disulphide homeostasis ischemia modified albumin and Ferroxidase as oxidative stress markers in women with obesity with insulin resistance
    Journal of Medical Biochemistry, 2019
    Co-Authors: Elif Ates, Süleyman Caner Karahan, Cemile Biçer, Ozcan Erel
    Abstract:

    Background: The purpose of the study was to determine oxidative stress-related plasma thiol/disulphide, ischemia-modified albumin (IMA) levels and Ferroxidase activity among women with obesity in insulin-resistant and non-insulin-resistant groups in comparison with an overweight group. Methods: We compared plasma thiol/disulphide, IMA levels, and Ferroxidase activity between the study groups. We analyzed plasma thiol/disulphide homeostasis with a newly developed automated measurement method; IMA with Albumin Cobalt Binding Test and Ferroxidase (ceruloplasmin) levels with an automated, colourimetric method. Results: There were no significant differences between insulin-resistant and non-insulin-resistant women with obesity in terms of plasma native thiol, total thiol, disulphide, disulphide/native thiol ratio, disulphide/total thiol or native thiol/total thiol values. Ferroxidase activity was higher in insulin-resistant than in non-insulin-resistant women with obesity and higher in the total women with obesity group than in the overweight subjects (p<0.001, and p=0.014, respectively). IMA was lower in the insulin-resistant group than in the non-insulin-resistant group and overweight groups (p=0.011, and p=0.042, respectively). Conclusions: The significantly greater increase in Ferroxidase activity in insulin-resistant subjects with obesity may reflect its role as a positive acute phase protein. These findings may be related to the pathogenesis of the disease. Changes in oxidative status occur in women with obesity, and partially in overweight subjects. The Ferroxidase activity of ceruloplasmin plays a crucial role in iron homeostasis and lowers oxidative stress by reducing the detrimental effects of iron.

  • a new kinetic automated assay to determine the Ferroxidase activity of ceruloplasmin
    Analytical Sciences, 2017
    Co-Authors: Salim Neselioglu, Merve Ergin, Ozcan Erel
    Abstract:

    A new kinetic and automated assay was developed to determine ceruloplasmin Ferroxidase activity. Ferrous ions are turned into ferric ions via catalytic activity of the Ferroxidase enzyme. Acetohydroxamic acid, a chromogen, forms a colored complex with ferric ions. This reaction was measured kinetically. Significant and strong correlations were obtained between the new acetohydroxamic method and the p-phenylenediamine oxidase (r = 0.988, p <0.001), o-dianisidine oxidase (r = 0.981, p <0.001), norfloxacine oxidase (r = 0.989, p <0.001) and nephelometric methods (r = 0.861, p <0.001). This reliable, applicable, user-friendly, and low-priced method can be performed fully automatically or with manual spectrophotometry, and can be used to measure the Ferroxidase activity of ceruloplasmin.

  • A New Kinetic, Automated Assay to Determine the Ferroxidase Activity of Ceruloplasmin.
    Analytical sciences : the international journal of the Japan Society for Analytical Chemistry, 2017
    Co-Authors: Salim Neselioglu, Merve Ergin, Ozcan Erel
    Abstract:

    A new kinetic and automated assay was developed to determine ceruloplasmin Ferroxidase activity. Ferrous ions are turned into ferric ions via catalytic activity of the Ferroxidase enzyme. Acetohydroxamic acid, a chromogen, forms a colored complex with ferric ions. This reaction was measured kinetically. Significant and strong correlations were obtained between the new acetohydroxamic method and the p-phenylenediamine oxidase (r = 0.988, p

  • automated measurement of serum Ferroxidase activity
    Clinical Chemistry, 1998
    Co-Authors: Ozcan Erel
    Abstract:

    A method is described for automated measurement of serum ceruloplasmin Ferroxidase activity. In this method, Fe2+ ions are used as the substrate. In addition, a new calibration system without ceruloplasmin is also presented. Optimum assay reaction conditions were determined. Maximal catalytic activity was obtained at 0.45 mol/L acetate buffer, pH 5.8. The reagents and calibrator are stable for at least 6 months. Significant correlations between serum Ferroxidase and p-phenylenediamine oxidase activities (r = 0.96; P <0.0001) and copper concentration (r = 0.93; P <0.0001) were found. The range for serum ceruloplasmin Ferroxidase activity in healthy persons was 198-1107 U/L, and in patients with bronchial asthma it was 601-1912 U/L.

Dennis N. Chasteen - One of the best experts on this subject based on the ideXlab platform.

  • facilitated diffusion of iron ii and dioxygen substrates into human h chain ferritin a fluorescence and absorbance study employing the Ferroxidase center substitution y34w
    Journal of the American Chemical Society, 2008
    Co-Authors: Fadi Bouabdallah, Paolo Arosio, Guanghua Zhao, Maura Poli, Giorgio Biasiotto, Dennis N. Chasteen
    Abstract:

    Ferritin is a widespread iron mineralizing and detoxification protein that stores iron as a hydrous ferric oxide mineral core within a shell-like structure of 4/3/2 octahedral symmetry. Iron mineralization is initiated at dinuclear Ferroxidase centers inside the protein where Fe(2+) and O(2) meet and react to form a mu-1,2-peroxodiferric intermediate that subsequently decays to form mu-oxo dimeric and oligomeric iron(III) species and ultimately the mineral core. Several types of channels penetrate the protein shell and are possible pathways for the diffusion of iron and dioxygen to the Ferroxidase centers. In the present study, UV/visible and fluorescence stopped-flow spectrophotometries were used to determine the kinetics and pathways of Fe(2+) diffusion into the protein shell, its binding at the Ferroxidase center and its subsequent oxidation by O(2). Three fluorescence variants of human H-chain ferritin were prepared in which Trp34 was introduced near the Ferroxidase center. They included a control variant no. 1 (W93F/Y34W), a "1-fold" channel variant no. 2 (W93F/Y34W/Y29Q) and a 3-fold channel variant no. 3 (Y34W/W93F/D131I/E134F). Anaerobic rapid mixing of Fe(2+) with apo-variant no. 1 quenched the fluorescence of Trp34 with a rate exhibiting saturation kinetics with respect to Fe(2+) concentration, consistent with a process involving facilitated diffusion. A half-life of approximately 3 ms for this process is attributed to the time for diffusion of Fe(2+) across the protein shell to the Ferroxidase center. No fluorescence quenching was observed with the 3-fold channel variant no. 3 or when Zn(2+) was prebound in each of the eight 3-fold channels of variant no. 1, observations indicating that the hydrophilic channels are the only avenues for rapid Fe(2+) access to the Ferroxidase center. Substitution of Tyr29 with glutamine at the entrance of the "1-fold" hydrophobic channel had no effect on the rate of Fe(2+) oxidation to form the mu-1,2-peroxodiferric complex (t(1/2) approximately 38 ms), a finding demonstrating that Tyr29 and, by inference, the "1-fold" channels do not facilitate O(2) transport to the Ferroxidase center, contrary to predictions of DFT and molecular dynamics calculations. O(2) diffusion into ferritin occurs on a time scale that is fast relative to the millisecond kinetics of the stopped-flow experiment.

  • iron detoxification properties of escherichia coli bacterioferritin attenuation of oxyradical chemistry
    Journal of Biological Chemistry, 2002
    Co-Authors: Fadi Bouabdallah, Nick Le E Brun, Allison Lewin, Geoffry R. Moore, Dennis N. Chasteen
    Abstract:

    Abstract Bacterioferritin (EcBFR) ofEscherichia coli is an iron-mineralizing hemoprotein composed of 24 identical subunits, each containing a dinuclear metal-binding site known as the “Ferroxidase center.” The chemistry of Fe(II) binding and oxidation and Fe(III) hydrolysis using H2O2 as oxidant was studied by electrode oximetry, pH-stat, UV-visible spectrophotometry, and electron paramagnetic resonance spin trapping experiments. Absorption spectroscopy data demonstrate the oxidation of two Fe(II) per H2O2 at the Ferroxidase center, thus avoiding hydroxyl radical production via Fenton chemistry. The oxidation reaction with H2O2 corresponds to [Fe(II)2-P]Z + H2O2→ [Fe(III)2O-P]Z + H2O, where [Fe(II)2-P]Z represents a diferrous Ferroxidase center complex of the protein P with net charge Z and [Fe(III)2O-P]Z a μ-oxo-bridged diferric Ferroxidase complex. The mineralization reaction is given by 2Fe2+ + H2O2 + 2H2O → 2FeOOH(core) + 4H+, where two Fe(II) are again oxidized by one H2O2. Hydrogen peroxide is shown to be an intermediate product of dioxygen reduction when O2 is used as the oxidant in both the ferroxidation and mineralization reactions. Most of the H2O2produced from O2 is rapidly consumed in a subsequent Ferroxidase reaction with Fe(II) to produce H2O. EPR spin trapping experiments show that the presence of EcBFR greatly attenuates the production of hydroxyl radical during Fe(II) oxidation by H2O2, consistent with the ability of the bacterioferritin to facilitate the pairwise oxidation of Fe(II) by H2O2, thus avoiding odd electron reduction products of oxygen and therefore oxidative damage to the protein and cellular components through oxygen radical chemistry.

  • ferrous ion binding to recombinant human h chain ferritin an isothermal titration calorimetry study
    Biochemistry, 2002
    Co-Authors: Fadi Bouabdallah, Paolo Arosio, Paolo Santambrogio, Xiaoke Yang, Christine Januschandler, Dennis N. Chasteen
    Abstract:

    Iron deposition within the iron storage protein ferritin involves a complex series of events consisting of Fe2+ binding, transport, and oxidation at Ferroxidase sites and mineralization of a hydrous ferric oxide core, the storage form of iron. In the present study, we have examined the thermodynamic properties of Fe2+ binding to recombinant human H-chain apoferritin (HuHF) by isothermal titration calorimetry (ITC) in order to determine the location of the primary ferrous ion binding sites on the protein and the principal pathways by which the Fe2+ travels to the dinuclear Ferroxidase center prior to its oxidation to Fe3+. Calorimetric titrations show that the Ferroxidase center is the principal locus for Fe2+ binding with weaker binding sites elsewhere on the protein and that one site of the Ferroxidase center, likely the His65 containing A-site, preferentially binds Fe2+. That only one site of the Ferroxidase center is occupied by Fe2+ implies that Fe2+ oxidation to form diFe(III) species might occur in ...

  • Ferroxidase kinetics of human liver apoferritin recombinant h chain apoferritin and site directed mutants
    Biochemistry, 1993
    Co-Authors: Shujun Sun, Sonia Levi, Paolo Arosio, Dennis N. Chasteen
    Abstract:

    A detailed study of the kinetics of iron(II) oxidation by molecular oxygen in natural and recombinant human apoferritins has been carried out using electrode oximetry to better understand the Ferroxidase activity of the protein shell. A comparative study of recombinant L-chain ferritin (rLF), recombinant H-chain ferritin (rHF), and variants has shown that (1) rLF lacks a Ferroxidase activity, confirming the results of previous studies; (2) the Ferroxidase site of rHF involves Glu-62 and His-65, presumably as Fe2+ ligands, since mutation of these residues abolishes most of the oxidase activity, in agreement with previous studies; and (3) mutation of both the putative Ferroxidase and nucleation site ligands in rHF renders the protein totally incapable of catalyzing the oxidation of Fe2+ whereas mutation of nucleation site ligands alone (Glu-61, Glu-64, and Glu-67) decreases the activity only slightly. Analysis of the kinetics of rHF and natural human liver ferritin (HLF) (4% H-chain, 96% L-chain) gave the following apparent parameters at pH 7: Km,O2 = 6 +/- 2 microM, Km,Fe = 80 +/- 10 microM, and kcat = 201 +/- 14 min-1 for rHF and Km,O2 = 60 +/- 12 microM, Km,Fe = 50 +/- 10 microM, and kcat = 31.2 +/- 0.6 min-1 for HLF. Furthermore, Zn2+ was shown to be a noncompetitive inhibitor of Fe2+ oxidation in rHF but a mixed inhibitor in HLF. These different forms of Zn2+ inhibition in the two proteins and the higher activity of HLF than expected, based on its H-chain composition as well as differences in their enzyme kinetic parameters, suggest that H- and L-chains cooperate in modulating the Ferroxidase activity of the apoferritin even though the L-subunit lacks a Ferroxidase site itself.

Paolo Arosio - One of the best experts on this subject based on the ideXlab platform.

  • facilitated diffusion of iron ii and dioxygen substrates into human h chain ferritin a fluorescence and absorbance study employing the Ferroxidase center substitution y34w
    Journal of the American Chemical Society, 2008
    Co-Authors: Fadi Ouabdallah, Paolo Arosio, Guanghua Zhao, Giorgio Iasiotto, Maura Poli, Dennis N Chastee
    Abstract:

    Ferritin is a widespread iron mineralizing and detoxification protein that stores iron as a hydrous ferric oxide mineral core within a shell-like structure of 4/3/2 octahedral symmetry. Iron mineralization is initiated at dinuclear Ferroxidase centers inside the protein where Fe2+ and O2 meet and react to form a μ-1,2-peroxodiferric intermediate that subsequently decays to form μ-oxo dimeric and oligomeric iron(III) species and ultimately the mineral core. Several types of channels penetrate the protein shell and are possible pathways for the diffusion of iron and dioxygen to the Ferroxidase centers. In the present study, UV/visible and fluorescence stopped-flow spectrophotometries were used to determine the kinetics and pathways of Fe2+ diffusion into the protein shell, its binding at the Ferroxidase center and its subsequent oxidation by O2. Three fluorescence variants of human H-chain ferritin were prepared in which Trp34 was introduced near the Ferroxidase center. They included a control variant no. 1...

  • facilitated diffusion of iron ii and dioxygen substrates into human h chain ferritin a fluorescence and absorbance study employing the Ferroxidase center substitution y34w
    Journal of the American Chemical Society, 2008
    Co-Authors: Fadi Bouabdallah, Paolo Arosio, Guanghua Zhao, Maura Poli, Giorgio Biasiotto, Dennis N. Chasteen
    Abstract:

    Ferritin is a widespread iron mineralizing and detoxification protein that stores iron as a hydrous ferric oxide mineral core within a shell-like structure of 4/3/2 octahedral symmetry. Iron mineralization is initiated at dinuclear Ferroxidase centers inside the protein where Fe(2+) and O(2) meet and react to form a mu-1,2-peroxodiferric intermediate that subsequently decays to form mu-oxo dimeric and oligomeric iron(III) species and ultimately the mineral core. Several types of channels penetrate the protein shell and are possible pathways for the diffusion of iron and dioxygen to the Ferroxidase centers. In the present study, UV/visible and fluorescence stopped-flow spectrophotometries were used to determine the kinetics and pathways of Fe(2+) diffusion into the protein shell, its binding at the Ferroxidase center and its subsequent oxidation by O(2). Three fluorescence variants of human H-chain ferritin were prepared in which Trp34 was introduced near the Ferroxidase center. They included a control variant no. 1 (W93F/Y34W), a "1-fold" channel variant no. 2 (W93F/Y34W/Y29Q) and a 3-fold channel variant no. 3 (Y34W/W93F/D131I/E134F). Anaerobic rapid mixing of Fe(2+) with apo-variant no. 1 quenched the fluorescence of Trp34 with a rate exhibiting saturation kinetics with respect to Fe(2+) concentration, consistent with a process involving facilitated diffusion. A half-life of approximately 3 ms for this process is attributed to the time for diffusion of Fe(2+) across the protein shell to the Ferroxidase center. No fluorescence quenching was observed with the 3-fold channel variant no. 3 or when Zn(2+) was prebound in each of the eight 3-fold channels of variant no. 1, observations indicating that the hydrophilic channels are the only avenues for rapid Fe(2+) access to the Ferroxidase center. Substitution of Tyr29 with glutamine at the entrance of the "1-fold" hydrophobic channel had no effect on the rate of Fe(2+) oxidation to form the mu-1,2-peroxodiferric complex (t(1/2) approximately 38 ms), a finding demonstrating that Tyr29 and, by inference, the "1-fold" channels do not facilitate O(2) transport to the Ferroxidase center, contrary to predictions of DFT and molecular dynamics calculations. O(2) diffusion into ferritin occurs on a time scale that is fast relative to the millisecond kinetics of the stopped-flow experiment.

  • ferrous ion binding to recombinant human h chain ferritin an isothermal titration calorimetry study
    Biochemistry, 2002
    Co-Authors: Fadi Bouabdallah, Paolo Arosio, Paolo Santambrogio, Xiaoke Yang, Christine Januschandler, Dennis N. Chasteen
    Abstract:

    Iron deposition within the iron storage protein ferritin involves a complex series of events consisting of Fe2+ binding, transport, and oxidation at Ferroxidase sites and mineralization of a hydrous ferric oxide core, the storage form of iron. In the present study, we have examined the thermodynamic properties of Fe2+ binding to recombinant human H-chain apoferritin (HuHF) by isothermal titration calorimetry (ITC) in order to determine the location of the primary ferrous ion binding sites on the protein and the principal pathways by which the Fe2+ travels to the dinuclear Ferroxidase center prior to its oxidation to Fe3+. Calorimetric titrations show that the Ferroxidase center is the principal locus for Fe2+ binding with weaker binding sites elsewhere on the protein and that one site of the Ferroxidase center, likely the His65 containing A-site, preferentially binds Fe2+. That only one site of the Ferroxidase center is occupied by Fe2+ implies that Fe2+ oxidation to form diFe(III) species might occur in ...

  • Construction of a Ferroxidase center in human ferritin L-chain.
    The Journal of biological chemistry, 1994
    Co-Authors: Sonia Levi, Paolo Santambrogio, Barbara Corsi, Ermanna Rovida, Anna Cozzi, Alberto Albertini, Paolo Arosio
    Abstract:

    Ferritins are 24-mer proteins which store and detoxify intracellular iron. Mammalian ferritins are made of two subunit types, the H- and L-chains, with different functional specificity. The H-chain has a metal-binding site (the Ferroxidase center) which confers Ferroxidase activity to the protein and accelerates iron incorporation. In the L-chain the center is substituted by a salt bridge. We performed several site-directed mutageneses in the L-chain with the aim to construct the center and confer Ferroxidase activity to the protein. Most variants were insoluble and did not refold into homopolymers, probably due to electrostatic repulsion introduced by the substitutions. However, they formed hybrids when they were renatured together with the L- or H-chains. The heteropolymers made of 90% L-chain and 10% of an L-variant with all the ligand residues of the H-chain center had 25-30% of the Ferroxidase activity of the H-chain homopolymer. This corresponds to the activity of an H/L heteropolymer with 7% H-chain. It is concluded that: (i) it is possible to construct a Ferroxidase center in the L-chain with an activity equivalent to that of the H-chain, (ii) the residues of the center interfere with the folding/assembly of the L-, but not of the H-chain, (iii) heteropolymers can be made even between ferritin subunits with large differences of refolding rates.

  • Ferroxidase kinetics of human liver apoferritin recombinant h chain apoferritin and site directed mutants
    Biochemistry, 1993
    Co-Authors: Shujun Sun, Sonia Levi, Paolo Arosio, Dennis N. Chasteen
    Abstract:

    A detailed study of the kinetics of iron(II) oxidation by molecular oxygen in natural and recombinant human apoferritins has been carried out using electrode oximetry to better understand the Ferroxidase activity of the protein shell. A comparative study of recombinant L-chain ferritin (rLF), recombinant H-chain ferritin (rHF), and variants has shown that (1) rLF lacks a Ferroxidase activity, confirming the results of previous studies; (2) the Ferroxidase site of rHF involves Glu-62 and His-65, presumably as Fe2+ ligands, since mutation of these residues abolishes most of the oxidase activity, in agreement with previous studies; and (3) mutation of both the putative Ferroxidase and nucleation site ligands in rHF renders the protein totally incapable of catalyzing the oxidation of Fe2+ whereas mutation of nucleation site ligands alone (Glu-61, Glu-64, and Glu-67) decreases the activity only slightly. Analysis of the kinetics of rHF and natural human liver ferritin (HLF) (4% H-chain, 96% L-chain) gave the following apparent parameters at pH 7: Km,O2 = 6 +/- 2 microM, Km,Fe = 80 +/- 10 microM, and kcat = 201 +/- 14 min-1 for rHF and Km,O2 = 60 +/- 12 microM, Km,Fe = 50 +/- 10 microM, and kcat = 31.2 +/- 0.6 min-1 for HLF. Furthermore, Zn2+ was shown to be a noncompetitive inhibitor of Fe2+ oxidation in rHF but a mixed inhibitor in HLF. These different forms of Zn2+ inhibition in the two proteins and the higher activity of HLF than expected, based on its H-chain composition as well as differences in their enzyme kinetic parameters, suggest that H- and L-chains cooperate in modulating the Ferroxidase activity of the apoferritin even though the L-subunit lacks a Ferroxidase site itself.

Rabindra K. Behera - One of the best experts on this subject based on the ideXlab platform.

  • Iron Mineralizing Bacterioferritin A from Mycobacterium tuberculosis Exhibits Unique Catalase-Dps-like Dual Activities
    Inorganic Chemistry, 2019
    Co-Authors: Abhinav Mohanty, Biswamaitree Subhadarshanee, Pallavi Barman, Chinmayee Mahapatra, B. Aishwarya, Rabindra K. Behera
    Abstract:

    Mycobacterium tuberculosis (Mtb) expresses heme binding protein nanocages, bacterioferritin A (BfrA), along with nonheme bacterioferritin B (BfrB). BfrA is unique to bacteria and, like BfrB, carries out Ferroxidase activity to synthesize iron oxide biominerals. The expression of BfrA, in the presence of BfrB, indicates that Mtb may utilize it for some additional purpose apart from its natural iron storage activity. However, the mechanism of Ferroxidase activity (iron biomineralization) in Mtb BfrA still remains unexplored. H2O2 is secreted by the host during host–pathogen interaction. In some bacteria, heme containing Bfr and/or Dps (DNA binding protein during starvation) detoxify H2O2 by utilizing it during their Ferroxidase activity. Interestingly, Mtb lacks the gene for Dps which protects DNA from H2O2-induced oxidative cleavage. Therefore, the current work investigates the kinetics of O2/H2O2-dependent Ferroxidase activity, DNA protection, and catalase-like activity of recombinant Mtb BfrA. Ferroxidas...

  • Iron Mineralizing Bacterioferritin A from Mycobacterium tuberculosis Exhibits Unique Catalase-Dps-like Dual Activities
    2019
    Co-Authors: Abhinav Mohanty, Biswamaitree Subhadarshanee, Pallavi Barman, Chinmayee Mahapatra, B. Aishwarya, Rabindra K. Behera
    Abstract:

    Mycobacterium tuberculosis (Mtb) expresses heme binding protein nanocages, bacterioferritin A (BfrA), along with nonheme bacterioferritin B (BfrB). BfrA is unique to bacteria and, like BfrB, carries out Ferroxidase activity to synthesize iron oxide biominerals. The expression of BfrA, in the presence of BfrB, indicates that Mtb may utilize it for some additional purpose apart from its natural iron storage activity. However, the mechanism of Ferroxidase activity (iron biomineralization) in Mtb BfrA still remains unexplored. H2O2 is secreted by the host during host–pathogen interaction. In some bacteria, heme containing Bfr and/or Dps (DNA binding protein during starvation) detoxify H2O2 by utilizing it during their Ferroxidase activity. Interestingly, Mtb lacks the gene for Dps which protects DNA from H2O2-induced oxidative cleavage. Therefore, the current work investigates the kinetics of O2/H2O2-dependent Ferroxidase activity, DNA protection, and catalase-like activity of recombinant Mtb BfrA. Ferroxidase activity by Mtb BfrA was found to proceed via the formation of a transient intermediate and its initial rate exhibited sigmoidal behavior, with increasing Fe2+ concentration. Moreover, Mtb BfrA exhibited catalase-like activity by evolving O2 upon reaction with H2O2, which gets inhibited in the presence of catalase inhibitors (NaN3 and NaCN). In addition, Mtb BfrA protected plasmid DNA from Fenton reagents (Fe2+ and H2O2), similar to Dps, by forming BfrA-DNA complexes. Thereby, Mtb BfrA executes multiple functions (Ferroxidase, catalase, and Dps-like activities) in order to cope with the host generated oxidative stress and to promote pathogenesis

Vivek Ambade - One of the best experts on this subject based on the ideXlab platform.

  • Serum Ferroxidase albumin ratio as a marken in pulmonary tuberculosis.
    Indian journal of clinical biochemistry : IJCB, 2007
    Co-Authors: Hs Batra, Parduman Singh, B. L. Somani, Ashish Gupta, Sangeetha Sampath, Vivek Ambade
    Abstract:

    Serum Ferroxidase and albumin levels were determined in 98 patients of tubercuiosis, of whom 49 were freshly diagnosed, sputum positive (group-I) & 49 were completely treated patients (group-II). Forty nine age and sex matched healthy individuals were taken as controls. Mean±SD of serum Ferroxidase and albumin levels in controls, group-I and group-II was found to be 864.35±106.35 IU/L & 3.91±0.234 g/dL, 1603.76±222.65 IU/L & 3.24±0.518 g/dL and 1001.78±201.63 IU/L & 3.82±0.43 g/dL, respectively. Serum Ferroxidase in group I was significantly higher as compared to controls and group-II (p