Potent inhibition of macrophage migration inhibitory factor (MIF) by myeloperoxidase-dependent oxidation of epicatechins
The objective of this study was to determine if MIF was susceptible to modification by epicatechins, a group of dietary flavonoids with known anti-inflammatory properties. Epicatechins are substrates for peroxidases including the neutrophil-derived enzyme myeloperoxidase. Here we show that oxidation of the catechol moiety of epicatechins to a ο-quinone by myeloperoxidase generates potent MIF inhibitors. Near complete inhibition of MIF by the MPO/H2O2/EC system was achieved at equimolar concentrations of EC and MIF even in the presence of other MPO substrates. We characterized the modification introduced by oxidized ...
Source: BJ Energy - June 11, 2014 Category: Biochemistry Authors: N Dickerhof, N J Magon, J D A Tyndall, A J Kettle, M B Hampton Tags: BJ Energy Source Type: research
Potent inhibition of macrophage migration inhibitory factor (MIF) by myeloperoxidase (MPO)-dependant oxidation of epicatechins
The objective of this study was to determine if MIF was susceptible to modification by epicatechins, a group of dietary flavonoids with known anti-inflammatory properties. Epicatechins are substrates for peroxidases including the neutrophil-derived enzyme myeloperoxidase. Here we show that oxidation of the catechol moiety of epicatechins to a ο-quinone by myeloperoxidase generates potent MIF inhibitors. Near complete inhibition of MIF by the MPO/H2O2/EC system was achieved at equimolar concentrations of EC and MIF even in the presence of other MPO substrates. We characterized the modification introduced by oxidized ...
Source: BJ Energy - June 11, 2014 Category: Biochemistry Authors: N Dickerhof, N J Magon, J D A Tyndall, A J Kettle, M B Hampton Tags: BJ Energy Source Type: research
Complex IV Deficient Surf1-/- Mice Initiate Mitochondrial Stress Responses
Mutations in SURF1 cytochrome c oxidase (COX) assembly protein are associated with Leigh’s syndrome, a human mitochondrial disorder that manifests as severe mitochondrial phenotypes and early lethality. In contrast, mice lacking the Surf1 protein (Surf1-/-) are viable and were previously shown to have enhanced longevity and a greater than 50% reduction in COX activity. We measured mitochondrial function in heart and skeletal muscle, and despite the significant reduction in COX activity, we found little or no difference in reactive oxygen species (ROS) generation, membrane potential, ATP production or respiration in ...
Source: BJ Energy - June 9, 2014 Category: Biochemistry Authors: D Alan Pulliam, S S. Deepa, Y Liu, S Hill, A Lin, A Bhattacharya, Y Shi, L Sloane, C Viscomi, M Zeviani, H Van Remmen Tags: BJ Energy Source Type: research
Discovery of InsP6-kinases as InsP6 dephosphorylating enzymes provides a new mechanism of cytosolic InsP6 degradation driven by the cellular ATP/ADP ratio
In this study, we demonstrated that lP6Ks change their kinase activity towards InsP6 at decreasing ATP/ADP ratio to an ADP phosphotransferase activity and dephosphorylate InsP6. Enantio-selective analysis revealed that Ins(2,3,4,5,6)P5 is the main InsP5 product of IP6K reaction, whereas the exclusive product of MINPP1 activity is the enantiomer Ins(1,2,4,5,6)P5. While lentiviral RNAi based depletion of MINPP1 at dropping cellular ATP/ADP ratios had no significant impact on Ins(2,3,4,5,6)P5 production, the use of the selective IP6K inhibitor TNP abolished the production of this enatiomer in different types of cells. Further...
Source: BJ Energy - May 28, 2014 Category: Biochemistry Authors: T Wundenberg, N Grabinski, H Lin, G W Mayr Tags: BJ Biomolecules Source Type: research
Mitochondrial-nuclear genome interactions in nonalcoholic fatty liver disease in mice
Nonalcoholic fatty liver disease (NAFLD) involves significant changes in liver metabolism characterized by oxidative stress, lipid accumulation, and fibrogenesis. Mitochondrial dysfunction and bioenergetic defects also contribute to NAFLD. Herein, we examined whether differences in mtDNA influence NAFLD. To determine the role of mitochondrial and nuclear genomes in NAFLD, Mitochondrial-Nuclear eXchange (MNX) mice were fed an atherogenic diet. MNX mice have mtDNA from C57BL/6J mice on a C3H/HeN nuclear background and vice versa. Results from MNX mice were compared to wild-type C57BL/6J and C3H/HeN mice fed a control or athe...
Source: BJ Energy - April 23, 2014 Category: Biochemistry Authors: A M. Betancourt, A L. King, J L. Fetterman, T Millender-Swain, R D. Finley, C R. Oliva, D Ralph Crowe, S W. Ballinger, S M. Bailey Tags: BJ Energy Source Type: research
Cystathionine-{gamma}-lyase/hydrogen sulfide system maintains cellular glutathione status
Hydrogen sulfide (H2S) has been implicated to exhibit an antioxidative property in many models. Cystathionine-γ-lyase (CSE) is an important enzyme responsible for endogenous H2S production in mammalian systems, but little is known about the modulation of endogenous H2S production and its antioxidative activity. We found that inhibiting CSE activity with propargylglycine (PAG) or silencing CSE expression by siRNA approach resulted in greater reduction of cell viability under exposure to oxidizing agent, hydrogen peroxide (H2O2). Cellular oxidative stress also increased significantly upon PAG inhibition or CSE knockdo...
Source: BJ Energy - April 7, 2014 Category: Biochemistry Authors: Z Lee, Y Low, S Huang, T Wang, L Deng Tags: BJ Energy Source Type: research
Acute nutrient regulation of mitochondrial glutathione redox state in pancreatic {beta}-cells
In conclusion, this study demonstrates that glucose and other nutrients acutely reduce mitochondrial but not cytosolic/nuclear EGSH in pancreatic β-cells under control conditions. (Source: BJ Energy)
Source: BJ Energy - March 28, 2014 Category: Biochemistry Authors: H K. Takahashi, L R. B. Santos, L P. Roma, J Duprez, C Broca, A Wojtusciszyn, J Jonas Tags: BJ Energy Source Type: research
Non-preferential fuelling of the Na{+}/K{+} ATPase pump
There is abundant evidence that glycolysis and the Na+/K+ ATPase pump are functionally coupled, and it is thought that the nature of the coupling is energetic, with glycolysis providing the ATP that fuels the pump. This notion has been instrumental to current models of brain energy metabolism. However structural and biophysical considerations suggest that the pump should also have access to mitochondrial ATP, which is much more abundant. Here we have investigated the source of ATP that fuels the Na+ pump in astrocytes, taking advantage of the high temporal resolution of recently-available FRET nanosens...
Source: BJ Energy - March 25, 2014 Category: Biochemistry Authors: I Fernández-Moncada, L Barros Tags: BJ Energy Source Type: research
Mitochondrial sulphydryl oxidase Erv1: both shuttle cysteine residues are required for its function with distinct roles
In this study, using yeast genetic approaches we showed that both shuttle cysteine residues of Erv1 are required for cell growth. In organelle and in vitro studies confirmed that both shuttle cysteines were indeed required for import of MIA-pathway substrates and Erv1 enzyme function to oxidise Mia40. Furthermore, our results revealed that the two shuttle cysteines of Erv1 are functionally distinct. While Cys33 is essential for forming the intermediate disulphide Cys33-Cys130’ and transferring electrons to the redox active-site directly, Cys30 plays two important roles: (i) dominantly interacts and receives electron...
Source: BJ Energy - March 13, 2014 Category: Biochemistry Authors: S Ang, M Zhang, T Lodi, H Lu Tags: BJ Biomolecules Source Type: research
Occurrence and subcellular distribution of the NAD(P)HX repair system in mammals
Hydration of NAD(P)H to NAD(P)HX, which inhibits several dehydrogenases, is corrected by an ATP-dependent dehydratase and an epimerase recently identified as the products of the vertebrate Carkd (Carbohydrate kinase domain) and Aibp (Apolipoprotein AI binding protein) genes, respectively. Our purpose was to assess the presence of these enzymes in mammalian tissues and determine their subcellular localisation. The Carkd gene encodes proteins with a predicted mitochondrial propeptide (mCARKD), a signal peptide (spCARKD), or neither of them (cCARKD). Confocal microscopy analysis of transfected CHO cells indicated that cCARKD ...
Source: BJ Energy - March 10, 2014 Category: Biochemistry Authors: A Yves Marbaix, D Tyteca, T Daniel Niehaus, A D Hanson, C Liette Linster, E Van Schaftingen Tags: BJ Metabolism Source Type: research
Oxidation modifies the structure and function of the extracellular matrix generated by human coronary artery endothelial cells
Extracellular matrix (ECM) materials such as laminin, perlecan, type IV collagen and fibronectin play a key role in determining the structure of the arterial wall and the properties of cells that interact with ECM. The aim of this study was to investigate the effect of peroxynitrous acid an oxidant generated by activated macrophages, on the structure and function of the ECM laid down by human coronary artery endothelial cells (HCAECs) in vitro and in vivo. It is shown that exposure of HCAEC-derived native matrix components to peroxynitrous acid (but not decomposed oxidant) at concentrations > 1 µM results in a lo...
Source: BJ Energy - February 12, 2014 Category: Biochemistry Authors: C Y. Chuang, G Degendorfer, A Hammer, J M. Whitelock, E Malle, M J. Davies Tags: BJ Energy Source Type: research
Studies on the regulation of the human E1 subunit of the 2-oxoglutarate dehydrogenase complex, including the identification of a novel calcium-binding site
The regulation of the 2-oxoglutarate dehydrogenase complex is central to intramitochondrial energy metabolism. Here, active full-length E1-subunit of the human complex has been expressed and shown to be regulated by Ca2+, adenine nucleotides and NADH, with NADH exerting a major influence on the K0.5 for Ca2+. We investigated two potential Ca2+-binding sites on E1, which we term site 1 (114DADLD) and site 2 (139ESDLD). Comparison of sequences from vertebrates with those from Ca2+ -insensitive non-vertebrate complexes suggest that site 1 may be the more important. Consistent with this view, a muta...
Source: BJ Energy - February 5, 2014 Category: Biochemistry Authors: C T. Armstrong, J Ross Anderson, R M. Denton Tags: BJ Metabolism Source Type: research
Decrease in cytochrome c oxidase reserve capacity diminishes robustness of Drosophila melanogaster and shortens life span
The phenotypic effects of under- and over-expression of cytochrome c oxidase (CcO) regulatory subunits IV and Vb were examined in Drosophila melanogaster in order to further test the hypothesis that suppression of the activities of mitochondrial electron transport chain (ETC) oxidoreductases retards the aging process and extends life span. Under-expression of both CcO subunits, induced by RNAi, resulted in decreases in the respective mRNA and protein levels, CcO holoenzyme activity, rate of mitochondrial respiration, walking speed and the life span of flies. Over-expression of CcO IV or CcO Vb in young flies increased the ...
Source: BJ Energy - January 21, 2014 Category: Biochemistry Authors: V Klichko, B H. Sohal, S N. Radyuk, W C. Orr, R S. Sohal Tags: BJ Energy Source Type: research
How the structure of the large subunit controls function in an oxygen-tolerant [NiFe]-hydrogenase
Salmonella enterica is an opportunistic pathogen that produces a [NiFe]-hydrogenase under aerobic conditions. Here, genetic engineering approaches were used to facilitate isolation of this enzyme, termed Hyd-5. The crystal structure was determined to a resolution of 3.2 Å and the hydrogenase was observed to comprise associated large and small subunits. The structure indicated that residue H229 from the large subunit was close to the proximal [4Fe-3S] cluster in the small subunit. In addition, H229 was observed to lie close to a buried glutamic acid (E73), which is conserved in oxygen-tolerant hydrogenases. Residues ...
Source: BJ Energy - January 16, 2014 Category: Biochemistry Authors: L Bowman, L Flanagan, P K. Fyfe, A Parkin, W N. Hunter, F Sargent Tags: BJ Biomolecules Source Type: research
Substrate interaction dynamics and oxygen control in the active site of thymidylate synthase ThyX
Thymidylate synthase ThyX, required for DNA synthesis in many pathogenic bacteria, is considered a promising anti-microbial target. It binds FAD and three substrates, producing deoxythymidine-5’-monophosphate from deoxyuridine-5’-monophosphate (dUMP). However, ThyX proteins also act as NADPH oxidase by directly reacting with oxygen. We investigated the dynamic interplay between the substrates and their role in competing with this wasteful and potentially harmful oxidase reaction in catalytically efficient ThyX from Paramecium bursaria Chlorella virus 1. dUMP binding accelerates the oxygen-insensitive half-rea...
Source: BJ Energy - January 15, 2014 Category: Biochemistry Authors: H F. Becker, K Djaout, I Lamarre, J E. Ulmer, D Schaming, V Balland, U Liebl, H Myllykallio, M H. Vos Tags: BJ Biomolecules Source Type: research
