Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Human ceruloplasmin (Cp) molecule is split into fragments by a contaminating protease upon storage of enzyme preparations. These fragments were separated by SDSPAAG electrophoresis and their Mr were estimated. Separate fragments were subjected to immunoelectrophoresis in agarose gel containing rabbit antibodies to human Cp. The immunoprecipitation peaks were then specifically stained to reveal the oxidase activity of the fragments towards o-dianisidine and L-cysteine. All the fragments were able to oxidize the latter, however, only the whole Cp molecule and the two of its largest fragments could oxidize the former. It seems likely that oxidation of L-cysteine does not require the presence of several copper ions constituting the catalytic centre of the blue oxidase (Cp.). contrarily, o-dianisidine seems to be oxidized by the multicopper active site of the enzyme rather than by the autonomously acting singular copper(s). Since o-dianisidine is oxidized by the fragments of Cp lacking the C-terminal polypeptide, which was thought to bind all the coppers of the active centre, it was assumed that some of the latter are bound by amino acids located in another part of the molecule.
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PMID:[Differences in the catalytic properties of fragments of the ceruloplasmin molecule]. 358 Apr 10

Ascorbic acid (AsA), added to nutrient broth at a concentration of 5 mmol/l, was bactericidal towards Campylobacter jejuni grown at 42 degrees C in a micro-aerobic atmosphere. Specific enzymes, radical scavengers, metal chelators and reducing agents were tested as possible antagonists to the cytotoxicity of AsA. The addition of catalase or of the metal chelators ceruloplasmin or Desferal did not prevent the cytotoxic effect of AsA. The addition of the hydroxyl radical scavengers mannitol, formate, histidine or DMSO also failed to counteract the toxicity of AsA. On the other hand, thiourea or cysteamine and the reducing agents cysteine or dithionite significantly increased the recovery of C. jejuni in the presence of AsA. Although the possibility of the involvement of hydroxyl radicals in AsA cytotoxicity cannot be ruled out, it appears that the toxic effect of AsA is due mostly to the formation of products of oxidation of AsA and particularly to dehydroascorbic acid (DHA). Dehydroascorbic acid was also bactericidal to C. jejuni at a concentration of 5 mmol/l. Of all the compounds tested, only cysteamine was effective in preventing (partially) the toxic effect of DHA. The growth of C. jejuni was not inhibited by the addition of 5 mmol/l of isoascorbic acid or sodium isoascorbate.
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PMID:Effect of ascorbic, isoascorbic and dehydroascorbic acids on the growth and survival of Campylobacter jejuni. 378 41

The capacity of D-penicillamine (DP) to produce or scavenge hydrogen peroxide was investigated. DP added to copper produced H2O2. Greater production was observed with copper sulfate than with copper bound to ceruloplasmin. In contrast, DP in the absence of copper scavenged H2O2, as measured in a direct assay. Furthermore, DP or D-cysteine alone reversed H2O2-mediated inhibition of concanavalin A-stimulated mononuclear cell proliferation. These opposing immunomodulating properties of DP may be relevant to its toxic or therapeutic actions in rheumatoid arthritis.
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PMID:In vitro production and scavenging of hydrogen peroxide by D-penicillamine. Relationship to copper availability. 402 87

The kinetics of decay in absorbance at 610 nm in the reaction of cysteine with ceruloplasmin was biphasic under anaerobic conditions. Admission of oxygen to the bleached ceruloplasmin restored the blue color to about 75% of the original value. However, under aerobic or anaerobic conditions an initial bleaching corresponded to a 25% decrease in blue color. This change was irreversible and remained after removal of excess cysteine from the reaction mixture by dialysis. There was no correlation between transient and steady-state kinetic parameters. Circular dichroism measurements showed a characteristic reduction in the negative band at 450 nm, which is specific for type 1b copper. Isolation and further studies on cysteine-modified ceruloplasmin with a lower A610/A280 ratio showed less than 10% reduction in enzyme activity toward p-phenylenediamine and o-dianisidine. Evidence is also presented that ceruloplasmin catalyzes the oxidation of cysteine with a one-electron reduction of oxygen and the formation of superoxide ion, which is then converted to H2O2 by ceruloplasmin. The effect of superoxide dismutase and catalase also confirms the presence of superoxide and H2O2. In sum, these data show that a permanent reduction of type 1b copper occurred when cysteine was used as a substrate. We conclude that there is a single electron transfer from cysteine directly to oxygen using one specific copper of ceruloplasmin, type 1b.
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PMID:The reaction of cysteine with ceruloplasmin copper. 608 86

Amino acid sequence studies of tryptic peptides isolated from a histidine-rich fragment (Cp F5) of human ceruloplasmin are described. Nineteen tryptic peptides were isolated from unmodified Cp F5 and five tryptic peptides were isolated from citraconylated Cp F5. These peptides, together with the cyanogen bromide fragments reported previously, allowed the assembly of the complete sequence of Cp F5. The fragment has 159 residues and a molecular weight of 18,650; it lacks carbohydrate, is rich in histidine, and contains 1 free cysteine that may be part of a copper-binding site. Human ceruloplasmin is a single polypeptide chain with a molecular weight of about 130,000 that is readily cleaved to large fragments by proteolytic enzymes; the relationships of Cp F5 to intact ceruloplasmin and to structural subunits earlier proposed is described. Cp F5 probably is an intact globular domain that is attached to the COOH-terminal end of ceruloplasmin by a labile interdomain peptide bond.
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PMID:Primary structure of a histidine-rich proteolytic fragment of human ceruloplasmin. II. Amino acid sequence of the tryptic peptides. 698 30

Several features of the catalytic oxidation of cysteine by ceruloplasmin and nonenzymic Cu(II) at pH 7 have been compared. The oxidation of cysteine by ceruloplasmin has several properties in common with the Cu(II) catalyzed oxidation of cysteine: pH maxima, thiol specificity, lack of inhibition by anions, and high sensitivity to inhibition by copper complexing reagents. These two catalysts differed in their molecular activity, in their ability to oxidize penicillamine and thioglycolate, and in that H2O2 was produced as a primary product only during Cu(II) oxidation. The oxidation of cysteine by ceruloplasmin was compared also with the ceruloplasmin catalyzed oxidation of o-dianisidine, a classical pH 5.5 substrate. The mechanism of the oxidation of cysteine by ceruloplasmin at pH 7 differed from that of o-dianisidine oxidation because the latter substrate was inhibited by anions but not by copper complexing agents. Spectral and other data suggest that during the ceruloplasmin reaction with cysteine there is a one electron transfer from cysteine to ceruloplasmin resulting in the specific reduction of type 1b Cu(II).
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PMID:Comparison of the catalytic oxidation of cysteine and o-dianisidine by cupric ion and ceruloplasmin. 711 74

Photoreduction of native ceruloplasmin, using the 454.5-nm line of an Ar+ laser, enables the identification of type-Ia, type-Ib and type-II copper. The circular dichroic spectra of N--3-bound type-II copper and SCN-- -bound type-II copper are obtained by the same procedure after anionic treatment of ceruloplasmin. From circular dichroic and resonance Raman evidence it appears that some of type-Ia and type-Ib copper ligands differ. Type-Ib copper ligands seem to the same as type-I copper in plastocyanin and azurin. Even though type-Ib copper is coordinated to one sulfur of cysteine and one sulfur of methionine (or disulfide of cystine), the methionine sulfur is not a ligand for type-Ia copper.
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PMID:Spectroscopic and photoreduction studies of copper chromophores in ceruloplasmin. 725 Jan 22

The use of activated thiopropyl-Sepharose for simple and rapid isolation of thiol peptides from large proteins was investigated using ceruloplasmin (a copper protein of molecular weight 134,000 containing three cysteines and six disulphides) as a test case. Optimal results for the immobilization of the protein to the activated gel were obtained at pH 4.0 in the presence of 8 M urea and 0.05 M ethylenediaminetetraacetic acid. In these conditions 96% of the protein thiol groups were attached to the adsorbent. The immobilized protein was digested with either pepsin or trypsin. The liberated non-thiol peptides were eluted from the gel together with the protease after the digestion. After washing, the covalently attached thiol peptides were eluted in reducing buffer, desalted on the hydrophobic gel Sephadex LH-20 and carboxymethylated. The peptides were purified in a two-step procedure involving gel filtration on Sephadex G-25 and either column electrophoresis or ion-exchange chromatography. The two sets of peptides were derived from four different regions in the protein. They were 12-39 residues in length and together accounted for 152 residues. It is shown that the peptide chain was susceptible to proteolytic attack also close to the point of attachment (two residues away). One peptide with two thiol groups proved to be derived from an area containing one disulphide bridge in addition to cysteine. This bridge could be identified in a separate experiment where a second enzyme was used to release the disulphide peptide after the first digestion and washings.
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PMID:Covalent chromatography as a means of isolating thiol peptides from large proteins: application to human ceruloplasmin. 732 Jan 3

Rat ceruloplasmin was purified by a three-step column chromatography procedure, utilizing DEAE-Sepharose, Sepharose CL-6B, and CM-Sephadex A50 columns. The molecular weight of rat ceruloplasmin determined by a molecular sieve column was 124,000 daltons. An optical density ratio (610 nm/280 nm) of 0.051 and a molar extinction coefficient of 8600 were obtained. A decrease in lysine in rat ceruloplasmin compared with human ceruloplasmin could account for its reduced anodal mobility. Other differences in the amino acid sequence of the rat ceruloplasmin included an increase in methionine and cystine/cysteine, and a decrease in histidine, tyrosine and tryptophan.
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PMID:Purification of rat ceruloplasmin. characterization and comparison with human ceruloplasmin. 738 73

The aim of the paper was to compare the erythrocyte serum and hepatic chomogenate antioxidative factors in order to assess their involvement in the detoxification events. The catalase and superoxiddismutase levels, important factors of the cellular defence, were sensitivity modulated in an acute experiment on Wistar rats. Carbofuran was administered in a non-lethal dose (7 mg/b.w.) single or in the presence of certain antioxidative agents (Vitamin E, Caffeine, Aspirin) EDTA and Cysteine for their role in protecting membranes against oxidative damage. The erythrocyte parameters (SOD, Catalase) were well related to seric factors, especially ceruloplasmin level, with varied magnitudes. GGT a marker of hepatotoxicity and G1-DH, a mitochondrial marker, were in a good correlation with erythrocyte factors. The changes seem to modulate a transmembranary disturbance process, as in hepatocyte pictures.
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PMID:Interference of some enzymatic modulators in the hepatic aggression induced by xenobiotics. 754 89


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