Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two subcellular fraction, P-1 and P-2, were isolated by differential centrifugation from 0.25 M sucrose muscle homogenates of the parasitic roundworm, Ascaris lumbricoides suum. Morphological studies indicated that P-1 fraction consisted of intact mitochondria, whereas P-2 fraction consisted almost exclusively of vesicular components. The difference spectrum of Ascaris microsomes showed a characteristic b-type cytochrome spectrum with three distinct absorption peaks at 560, 525, and 424 nm. However, the alpha-peak at 560 nm was asymmetric with a shoulder at 555 nm. This microsomal b-type cytochrome was reduced by NADH, which was inhibited by rotenone and HgCl2. The reduced b-type cytochrome was easily reoxidized by shaking. NADH-oxidase activity observed in Ascaris microsomes was inhibited by rotenone, but not by KCN, NaN3, and antimycin A. On the other hand, NADH-cytochrome c and NADH-neotetrazolium (NT) reductase activities in Ascaris microsomes were not inhibited by antimycin A and rotenone, but were inhibited by HgCl2. Further observations indicated that neither HgCl2 nor rotenone inhibited Ascaris microsomal NADH-ferricyanide (FC) reductase activity, but rabbit antibody prepared against the purified NADH-FC reductase inhibited the NADH-cytochrome c reductase activity, the reduction of b-type cytochrome and the NADH-oxidase activity, as well as microsomal NADH-FC reductase activity.
 ...
PMID:Biochemical studies on the muscle microsomes of Ascaris lumbricoides var. suum. I. Biochemical characterization and electron transport of Ascaris microsomes. 42 35

Studies were undertaken to investigate the principal actions underlying mercury-induced oxidative stress in the kidney. Mitochondria from kidneys of rats treated with HgCl2 (1.5 mg/kg i.p.) demonstrated a 2-fold increase in hydrogen peroxide (H2O2) formation for up to 6 hr following Hg(II) treatment using succinate as the electron transport chain substrate. No increase in H2O2 formation was observed when NAD-linked substrates (malate/glutamate) were used, suggesting that Hg(II) affects H2O2 formation principally at the ubiquinone-cytochrome b region of the mitochondrial respiratory chain in vivo. Together with increased H2O2 formation, mitochondrial glutathione (GSH) content was depleted by more than 50% following Hg(II) treatment, whereas formation of thiobarbiturate reactive substances (TBARS), indicative of mitochondrial lipid peroxidation, was increased by 68%. Studies in vivo revealed a significant concentration-related depolarization of the inner mitochondrial membrane following the addition of Hg(II) to mitochondria isolated from kidneys of untreated rats. This effect was accompanied by significantly increased H2O2 formation, GSH depletion and TBARS formation linked to both NADH dehydrogenase (rotenone-inhibited) and ubiquinone-cytochrome b (antimycin-inhibited) regions of the electron transport chain. Oxidation of pyridine nucleotides (NAD[P]H) was also observed in mitochondria incubated with Hg(II) in vitro. In further studies in vitro, the potential role of Ca2+ in Hg(II)-induced mitochondrial oxidative stress was investigated. Ca2+ alone (30-400 nmol/mg protein) produced no increase in H2O2 and only a slight increase in TBARS formation when incubated with kidney mitochondria isolated from untreated rats. However, Ca2+ significantly increased H2O2 and TBARS formation elicited by Hg(II) at the ubiquinone-cytochrome b region of the mitochondrial electron transport chain, whereas TBARS formation was decreased significantly when the Ca2+ uptake inhibitors, ruthenium red or [ethylenebis(oxyethylenenitrilo)]tetraacetic acid (EGTA), were included with Hg(II) in the reaction mixtures. These findings support the view that Hg(II) causes depolarization of the mitochondrial inner membrane with consequent increased H2O2 formation. These events, coupled with Hg(II)-mediated GSH depletion and pyridine nucleotide oxidation, create an oxidant stress condition characterized by increased susceptibility of mitochondrial membranes to iron-dependent lipid peroxidation (TBARS formation). Since increased H2O2 formation, GSH depletion and lipid peroxidation were also observed in vivo following Hg(II) treatment, these events may underlie oxidative tissue damage caused by mercury compounds. Moreover, Hg(II)-induced alterations in mitochondrial Ca2+ homeostasis may exacerbate Hg(II)-induced oxidative stress in kidney cells.
 ...
PMID:Studies on Hg(II)-induced H2O2 formation and oxidative stress in vivo and in vitro in rat kidney mitochondria. 851 85