Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.16.3.1 (ceruloplasmin)
 5,074 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have prepared C3b covalently linked to IgG via a hydroxylamine-sensitive bond between the C3b alpha' chain and sites predominantly, but not exclusively, located in the IgG heavy chain. This C3b species displays relative resistance to inactivation by factors H and I when compared with free C3b. This resistance appears to be due entirely to reduced affinity of C3b-IgG for factor H. Resistance to inactivation is not conferred on C3b by binding to another serum glycoprotein of similar size, ceruloplasmin, and may be a special property of IgG. C3b-IgG demonstrates an enhanced capacity to consume serum C3 relative to C3b. These alterations of the behavior of C3b when bound to IgG may in part explain the augmentation of alternative pathway activity by IgG. In addition, IgG-induced protection of C3b might influence both complement-mediated killing and phagocytosis of bacteria, as well as modify the in vivo handling of IgG-containing soluble immune complexes.
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PMID:C3b covalently bound to IgG demonstrates a reduced rate of inactivation by factors H and I. 623 98

Previous reports of superoxide scavenging and ferroxidase-like activity of nitroxide free radicals have greatly increased interest in the ability of these compounds to protect cells against oxidative cellular damage. In the present study we investigated the antioxidant properties of the six membered nitroxide 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) in various assays. TEMPO (5 mM) inhibited the hydroxyl radical mediated generation of ethylene from 2-keto-4-methylthiobutyric acid to 31.2 +/- 4.0% of control values. Furthermore, we noted that TEMPO had the ability to maintain iron in its ferric form, a finding with strong implications for the interpretation of the ferricytochrome c reduction assay. TEMPO may be reduced to an electron paramagnetic resonance silent hydroxylamine by a number of pathways. TEMPO absorption intensity decay (TAID) was monitored to investigate the effects of hydrogen peroxide on Cu,Zn-SOD. TEMPO was found to effectively scavenge or suppress formation of hydroxyl radicals inside Cu,Zn-SOD. The generation of hydroxyl radical was confirmed by employing the conventional spin trapping agent DMPO. Using radical scavengers unable to penetrate the Cu,Zn-SOD enzyme (e.g., mannitol, ethanol, albumin) or compounds with access to copper within the Cu,Zn-SOD enzyme (azide and cyanide), we could not detect hydroxyl radicals outside the enzyme. Finally, since the electron paramagnetic resonance absorption intensity is directly proportional to the concentration of TEMPO spins, loss of absorption intensity provided information concerning radical-mediated processes. Therefore, the decay kinetics of TEMPO may be used as a very sensitive alternative to conventional spin traps.
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PMID:An electron paramagnetic resonance study of the antioxidant properties of the nitroxide free radical TEMPO. 813 84

We cloned and sequenced the ferric ion-binding protein, ferritin, from the nervous system of the pulmonate snail, Helix pomatia. Helix H-ferritin cDNA contains a 519-bp open reading frame (ORF) and predicts an iron-responsive element (IRE) at the 5'-untranslated region (5'-UTR) of the ferritin mRNA. The deduced amino acid sequence revealed 86% similarity with Lymnaea stagnalis ferritin and about 70% similarity with vertebrate H-ferritin. While secreted ferritin isoforms contain a signalling sequence at their N-terminal end, Helix ferritin does not contain this sorting signal indicating that it is restricted to the cytoplasm. The amino acid ligands at positions Glu25, Tyr30, Glu59, Glu60, His63, Glu105 and Gln139 indicate an active ferroxidase site in Helix ferritin. In situ hybridization visualized ferritin mRNA in neuronal cell bodies but not in the neuropil. In contrast, ferritin-immunoreactive protein was localized in cell bodies and neurites. We further demonstrate that the NO donors S-nitroso-N-acetylpenicillamine (SNAP), or hydroxylamine (HA), increase the intracellular ferritin mRNA level by about 55%. In conclusion, our findings show that Helix neurons express an intracellular H-ferritin isoform and suggest that iron and NO metabolism are coupled.
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PMID:Nitric oxide up-regulates ferritin mRNA level in snail neurons. 1132 43

Ceruloplasmin (ferroxidase) is a copper-binding protein known to promote Fe(2+) oxidation in plasma of mammals. In addition to its classical ferroxidase activity, ceruloplasmin is known to catalyze the oxidation of various substrates, such as amines and catechols. Assays based on cyclic hydroxylamine oxidation are used to quantify and detect free radicals in biological samples ex vivo and in vitro. We show here that human ceruloplasmin promotes the oxidation of the cyclic hydroxylamine 1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine hydrochloride (CPH) and related probes in Chelex-treated phosphate buffer and rat serum. The reaction is suppressed by the metal chelators DTPA, EDTA, and desferal, whereas heparin and bathocuproine have no effect. Catalase or superoxide dismutase additions do not interfere with the CPH-oxidation yield, demonstrating that oxygen-derived free radicals are not involved in the CPH oxidation mediated by ceruloplasmin. Plasma samples immunodepleted of ceruloplasmin have lower levels of CPH oxidation, which confirms the role of ceruloplasmin (ferroxidase) as a biological oxidizing agent of cyclic hydroxylamines. In conclusion, we show that the ferroxidase activity of ceruloplasmin is a possible biological source of artifacts in the cyclic hydroxylamine-oxidation assay used for reactive oxygen species detection and quantification.
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PMID:Ceruloplasmin (ferroxidase) oxidizes hydroxylamine probes: deceptive implications for free radical detection. 2282 65