Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A novel extracellular mycobacterial enzyme was identified in the ruminant pathogen Mycobacterium paratuberculosis. The enzyme was capable of mobilizing iron from different sources such as ferric ammonium citrate, ferritin, and transferrin by reduction of the metal. The purified reductase had a calculated Mr of 17,000, was sensitive to proteinase K treatment, and had an isoelectric point of pH 9. Analysis of the amino acid composition revealed glycine, serine, asparagine (or aspartic acid), and glutamine (or glutamic acid) as the most frequently occurring residues. Enzymatic activity was highest at 37 degrees C and between pH 5 and 10. The calculated Km and Vmax for ferric ammonium citrate were 0.213 mM and 0.345 mM min(-1) mg(-1), respectively. Using a specific antireductase antibody in immunoelectron microscopy, we were able to detect the enzyme associated with intracellular mycobacteria in naturally M. paratuberculosis-infected bovine tissue. We prepose that the reductase of M. paratuberculosis represents an alternative strategy of mycobacteria to mobilize ferric iron and discuss its potential role in bacterial evasion of intracellular defense mechanisms.
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PMID:Identification and characterization of a novel extracellular ferric reductase from Mycobacterium paratuberculosis. 945 31

Distribution of radioiron to various tissues after intraperitoneal injections was examined in Atlantic salmon and rainbow trout. Liver and spleen were found to be the major iron storage tissues. Injections of 1 or 5 mg iron as ferric ammonium citrate led to a fall in hemoglobin levels in both species after 2 d. Hemoglobin levels returned to normal levels in rainbow trout after 8 d, but Atlantic salmon had not recovered, and Hb levels fell below 3 g/100 mL. In both species, the fall in Hb was associated with a raise in iron levels in spleen and liver, suggesting damage to erythrocytes. Atlantic salmon liver ferritin showed a two- to threefold increase, while rainbow trout showed a sixfold increase, and a more rapid response. The toxic effect of iron in fish appears to be different from the effect in other vertebrates.
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PMID:Effects of acute iron overload on Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss). 952 42

Astrocytes provide a vital protective function in the brain. These cells are also vulnerable to oxidative stress, thus their loss of function could contribute to neurodegeneration. The goal of this study is to develop a cell culture model to study oxidative stress in astrocytes. Enriched astrocytic cultures were generated from neonatal mice. tertiary-butyl hydroperoxide (t-bOOH) was used as an exogenous peroxide and lactate dehydrogenase (LDH) release as a measure of loss of viability. Exposure to t-bOOH resulted in a linear increase in astrocytic death reaching 91.2% after 4 h exposure. That cell death was due to oxidative injury, was shown by the ability of the antioxidant N,N'-diphenyl-1,4-phenylenediamine (DPPD) to protect the t-bOOH treated cells. The involvement of iron in cell toxicity was demonstrated by the ability of the iron specific chelator desferal (DF) to completely prevent t-bOOH induced LDH release. Cells treated with a lipid soluble iron compound 3,5, 5-trimethyl (hexanoyl) ferrocene (TMH-Ferrocene), were more vulnerable to t-bOOH whereas neither ferrous ammonium sulfate (FAS) nor ferric ammonium citrate (FAC) had an effect. The increased sensitivity of the cells exposed to TMHF was reversible with the iron chelator desferal. Addition of recombinant human heavy chain ferritin or human apo-transferrin (Tf) did not alter LDH release. Electron microscopic analysis indicated astrocytes exposed to t-bOOH exhibited mitochondrial swelling prior to cell death (lactate dehydrogenase release). Additional increases in mitochondrial swelling were seen when the astrocytes were exposed to the lipophilic iron compound TMH-ferrocene and t-bOOH. These studies show that astrocytes are exquisitely sensitive to oxidative stress and that their vulnerability is related to and enhanced by iron. Decreased mitochondrial function in response to oxidative stress may precede cell death.
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PMID:An in vitro model for analysis of oxidative death in primary mouse astrocytes. 955 79

Ferritin is the major intracellular iron storage protein which has been shown to protect cells against oxidative damage. Recent reports that an inherited abnormality in human ferritin synthesis is associated with early bilateral cataracts underscore the importance of understanding ferritin synthesis and iron storage in lens epithelial cells. We previously demonstrated that ascorbic acid greatly increases de novo synthesis of ferritin in lens epithelial cells. The objectives of the present study were to determine: (1) the effects of ascorbic acid and ferric ammonium citrate on iron uptake by canine lens epithelial cells from iron bound to transferrin and from ferric chloride and (2) the incorporation of this element into ferritin. Iron uptake by lens epithelial cells from 59ferric chloride was 20 times higher than from 59iron-transferrin and iron deposition into ferritin was 8-fold higher when 59ferric chloride was the source. Ascorbic acid had a stimulatory effect on iron uptake from transferrin and on incorporation of this element into ferritin. The ascorbic acid-induced increase of iron uptake required de novo protein synthesis but not specifically de novo ferritin biosynthesis. Although ferritin is not directly involved in iron uptake, the level of ferritin protein could control the pool of intracellular iron. The present results indicate that iron homeostasis in lens epithelial cells is affected mainly by changes in apoferritin synthesis, which is greatly stimulated by ascorbic acid, rather than by altering the rate of protein degradation, which is very slow in these cells under all circumstances. Ferric ammonium citrate activates iron uptake from transferrin in a wide range of cell lines by generation of free radicals. Ferric ammonium citrate also increased iron uptake from Tf in lens epithelial cells. Ferric ammonium citrate treated cells incorporated 5 times more iron and deposited 2 times more iron into ferritin than control cells. Increased incorporation of iron into ferritin was due to ferric ammonium citrate-induced stimulation of de novo ferritin synthesis rather than an increased rate of iron deposition into pre-existing ferritin. Ferric ammonium citrate had a different effect on iron uptake from ferric chloride; total iron uptake was not significantly increased while deposition into ferritin was significantly decreased. These results demonstrate that iron homeostasis in lens epithelial cells is regulated by ascorbic acid and by changes in the rate of de novo ferritin synthesis. In addition, the differences in iron uptake from transferrin and ferric chloride and its subsequent incorporation into ferritin suggests that the mechanisms by which iron is incorporated into ferritin are source dependent.
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PMID:The effect of ascorbic acid and ferric ammonium citrate on iron uptake and storage in lens epithelial cells. 965 1

The prokaryotic ferritin gene of Campylobacter jejuni was overexpressed in Escherichia coli under control of the bacteriophage T7 promoter and the protein (Cj-FTN) purified. Preliminary crystallization experiments have been performed using the hanging-drop vapour-diffusion method with ammonium sulfate as the precipitant. Diffraction studies show the crystals belong to the I432 space group (a = 151.52 A). Structure solution by molecular replacement is in progress while crystal quality improvement is carried out.
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PMID:Expression, purification, crystallization and preliminary X-ray diffraction results from Campylobacter jejuni ferritin. 1008 31

The ferritins were purified from liver homogenates of buffalo, camel, cattle, sheep and shark by thermal denaturation, ammonium sulphate fractionation, Sephacryl S-300 gel filtration and DEAE-blue gel affinity chromatography. The yield and iron content of affinity-purified liver ferritins ranged from 0.008 to 0.052 mg/g and 3.17% to 11.4% respectively. As they are glycoproteins, the ferritins contained variable amounts of neutral carbohydrates. Except for shark ferritin, the ferritins all exhibited immunological cross-reactivity with anti-buffalo liver ferritin and anti-horse spleen ferritin by immunodiffusion and immunoelectrophoresis. Gel electrophoresis, gel filtration and ultracentrifugal analysis indicated the presence of a monomeric ferritin in all cases. SDS-gel electrophoresis of shark ferritin gave a protein band of 18 kDa. Ovine, buffalo and bovine ferritin comprised two protein subunits, the H (20 and 21 kDa) and the L types (18 and 19 kDa). Oligomeric ferritin subunits with molecular weights of 27, 37 and 55 kDa were also found for bovine and buffalo ferritin. SDS-PAGE of camel ferritin revealed a complex pattern with four prominent bands of 61, 51, 44 and 39 kDa. Two fast-migrating components of 15 and 16 kDa were also found in the purified liver ferritins, including reference preparations. The PO4(3-)/Fe ratios of purified shark (0.10) and bovine ferritin (0.12) were similar to that of standard equine spleen ferritin (0.11). However, the ratio was higher in ovine (0.17), camel (0.22) and bovine (0.26) ferritins. The amino acid compositions, molecular weights and sedimentation coefficients of the different liver ferritins were similar.
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PMID:Purification and characterization of liver ferritins from different animal species. 1040 20

Ferritin from the liver of fresh, salt and brackish water fishes was purified by thermal denaturation of liver homogenate followed by ammonium sulphate fractionation and Sephacryl S-300 gel filtration. Yield and iron content of purified fish ferritins were 0.016-0.026 mg/g of wet tissue and 4-14%, respectively. The iron content of ferritins from marine and brackish species was higher than from fresh water species. The phosphate/iron ratio ranged from 0.5 to 1.8 and was higher than mammalian ferritins. The fish ferritins have 5-6% neutral carbohydrate. Native gel electrophoresis and molecular weight analysis revealed the presence of a monomeric ferritin. SDS-gel electrophoresis and immunoblotting showed a single protein band of 21 kDa suggesting the presence of similar sized subunits in the native structure of fish ferritins. Isoelectric focusing revealed microheterogeneity with five to seven bands of pI values between 4.1 and 7.0. Variations in the amino acid composition were observed. Proline and arginine were not detected in murrel and salmon species, respectively. High proline and low tyrosine contents were recorded for perch ferritin. Immunological studies by non-competitive indirect ELISA revealed varying degrees of cross-reactivity. Mammalian ferritins exhibited a moderate cross-reactivity with anti-fish ferritin. On the contrary, very low or no cross-reactivity was observed between fish ferritin and anti-mammalian ferritin. Ferritins from bony fishes such as murrel and rohu exhibited a high degree of cross-reactivity with anti-shark ferritin. However, a moderate cross-reactivity was observed between shark and anti-murrel ferritin. Ferritin from marine bony fishes, salmon and mackerel and perch (brackish) showed a low to very low cross-reactivity with both the antisera.
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PMID:Purification and characterization of fish liver ferritins. 1048 Dec 57

Crystals of recombinant mouse L-chain apoferritin were obtained by the hanging-drop technique using ammonium sulfate as precipitant. Two crystal forms were observed in the same drop. The crystals belong to either the P2 monoclinic or to the P42(1)2 tetragonal space group. The monoclinic crystals diffracted to beyond 2.4 A resolution but were systematically twinned, while the tetragonal crystals diffracted to beyond 2.9 A. These crystallization conditions in the absence of metal salts should facilitate the study of the interaction between L-chain ferritins and heavy metals, particularly the iron core.
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PMID:Crystallization and preliminary X-ray diffraction data of mouse L-chain apoferritin crystals. 1077 33

Camel kidney ferritin was isolated from a tissue homogenate by thermal denaturation, ammonium sulphate fractionation, Sephacryl S-300 gel filtration and DEAE-blue gel affinity chromatography. The yield and the iron and neutral carbohydrate contents were 0.012 mg/g wet tissue, 4.0% and 2.7%, respectively. The phosphate:iron ratio was 0.13, twofold lower than that reported for camel liver ferritin. Native gel electrophoresis revealed the presence of a monomeric ferritin. SDS gel electrophoresis and immunoblotting showed two types of subunits, heavy and light, contrary to the extensive heterogeneity observed in camel liver ferritin. In general, the tissue ferritins shared a similar amino acid composition. However, a twofold lower glycine and an eightfold higher arginine content were recorded for camel kidney ferritin. In addition, kidney ferritin had a relatively high content of glutamic acid. Cross-reactivity studies by Ouchterlony double diffusion and noncompetitive indirect ELISA revealed a distinct cross-reactivity between buffalo ferritin antiserum and camel liver ferritin, but camel liver ferritin showed only weak cross-reactivity.
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PMID:Camel kidney ferritin: isolation and partial characterization. 1086 47

The objective of this review is to examine the biogenesis of lysosomes during the endocytic flow of plasma membrane. Two models have been proposed to explain the formation of lysosomes by this process: the "maturational" and the "stationary" models. According to the former, pinocytotic vesicles fuse among themselves to yield endosomes, which in turn, transform first into multivesicular bodies (MVB) and then into mature lysosomes. Therefore, endosomes and lysosomes would be transient organelles. On the other hand, the "stationary" model proposes that the endocytic pathway is formed by functionally and physically distinct compartments. Cultured cells exposed to ammonium chloride (NH4Cl) and leupeptin after a pulse of cationic ferritin were recently used to freeze endosomes and lysosomes. NH4Cl produced a retention of cationic ferritin in endosomes, indicating that this agent interfered with the endosomal/lysosomal progression. Leupeptin did not affect this process. The number of lysosomes increased in cells treated with both lysosomotropic agents. Thus, NH4Cl affected the endosomal and lysosomal compartments, whereas leupeptin had a preferential effect on lysosomes. Mice mutants with defects of plasma membrane degradation, including a Tay-Sachs model, a Sandhoff disease model, as well as, mice with the inactivated prosaposin gene were used to analyze the biogenesis of lysosomes. Thin sections of mutant cells were examined under the electron microscope, and the analysis revealed a selective accumulation of MVBs and the disappearance of lysosomes, suggesting that the formation of MVBs is a required step in lysosomal maturation and that the intravesicular content of MVBs is necessary for the digestion of plasma membrane components. Taken together, these data indicate that endosomes and MVBs are preceding steps in lysosomal biogenesis and that endosomes, MVBs, and lysosomes are transient organelles.
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PMID:Biogenesis of lysosomes by endocytic flow of plasma membrane. 1090 40


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