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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Xanthine oxidase exhibits ferroxidase activity and previously has been shown to catalyze the oxidative incorporation of iron into apotransferrin, the iron transport protein of plasma. These studies demonstrate that xanthine oxidase also efficiently promotes the oxidative incorporation of iron into apoferritin, the major iron storage protein of vertebrates, and that the ferroxidase activity of intestinal xanthine oxidase could be important in determining the fraction of iron within the intestinal mucosa cell partitioned to ferritin versus the iron that remains in a transient pool for rapid transport to plasma.
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PMID:Xanthine oxidase: an efficient promoter of the iron loading of apoferritin. 795 Oct 57

Ferritins are 24-mer proteins which store and detoxify intracellular iron. Mammalian ferritins are made of two subunit types, the H- and L-chains, with different functional specificity. The H-chain has a metal-binding site (the ferroxidase center) which confers ferroxidase activity to the protein and accelerates iron incorporation. In the L-chain the center is substituted by a salt bridge. We performed several site-directed mutageneses in the L-chain with the aim to construct the center and confer ferroxidase activity to the protein. Most variants were insoluble and did not refold into homopolymers, probably due to electrostatic repulsion introduced by the substitutions. However, they formed hybrids when they were renatured together with the L- or H-chains. The heteropolymers made of 90% L-chain and 10% of an L-variant with all the ligand residues of the H-chain center had 25-30% of the ferroxidase activity of the H-chain homopolymer. This corresponds to the activity of an H/L heteropolymer with 7% H-chain. It is concluded that: (i) it is possible to construct a ferroxidase center in the L-chain with an activity equivalent to that of the H-chain, (ii) the residues of the center interfere with the folding/assembly of the L-, but not of the H-chain, (iii) heteropolymers can be made even between ferritin subunits with large differences of refolding rates.
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PMID:Construction of a ferroxidase center in human ferritin L-chain. 798 45

Ferritin inhibition of myelopoiesis has been associated with intrinsic ferroxidase activity of heavy-chain ferritin and with production of a monokine inhibitor of lipopolysaccharide (LPS)-augmented monocytopoiesis. We report here that intrinsic ferroxidase activity of heavy-chain ferritin is required for stimulated production of the monokine inhibitor of LPS-augmented monocytopoiesis.
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PMID:Ferritin stimulation of a monokine inhibitor of lipopolysaccharide-augmented myelopoiesis is ferroxidase dependent. 800 86

The effect of route of erythropoietin (EPO) administration was assessed in sixteen hemodialysis patients who completed a randomised crossover study of thrice weekly subcutaneous (SC) and intravenous (IV) erythropoietin with an EPO-free washout period separating the two phases of treatment. Route of EPO administration had no significant effect on absolute reticulocyte counts, and change in hemoglobin (Hb) during the first six weeks of therapy, at a constant EPO dose (120 iu/kg/week). Similarly, there was no significant difference in EPO dose requirement between the two routes, both during and after correction of anemia, and after maintenance of target Hb (10-12 g/dl) for an eight-week period (end of maintenance period dose; median [range]; SC EPO: 120 [30-367] iu/kg/week, IV EPO: 124.5 [37-377] iu/kg/week). Following EPO withdrawal, Hb fell at a rate of 0.38 (0.14-0.69) g/dl/week. Route of EPO administration did not influence the incidence of thrombotic and hypertensive side effects, or increases in dialysis heparin requirement and albumin, and decreases in ferritin, alpha-1-antitrypsin and ceruloplasmin during the study period. In conclusion, thrice weekly SC and IV EPO are comparable in terms of efficacy and safety.
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PMID:Erythropoietin response and route of administration. 805 Feb 10

X-Ray analysis of the ferritin of Escherichia coli (Ec-FTN) and of Ec-FTN crystals soaked in (NH4)2Fe(SO4)2 has revealed the presence of three iron-binding sites per subunit. Two of these form a di-iron site in the centre of the subunit as has been proposed for the 'ferroxidase centres' of human ferritin H chains. This di-iron site, lying within the 4-alpha-helix bundle, resemble those of ribonucleotide reductase, methane monoxygenase and haemerythrin. The third iron is bound by ligands unique to Ec-FTN on the inner surface of the protein shell. It is speculated that this state may represent the nucleation centre of a novel type of Fe(III) cluster, recently observed in Ec-FTN.
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PMID:Direct observation of the iron binding sites in a ferritin. 807 May 75

Iron metabolism parameters (increased level of serum ferritin, appearance of an iron pool specifically unrelated to transferrin, reduced ceruloplasmin level, etc.) were found changed in subjects who participated in liquidation of Chernobyl power plant accident aftereffects. These shifts in iron metabolism are explained by reduced antioxidant activity of plasma and indicative of mononuclear phagocyte dysfunction, thus necessitating a dynamic monitoring of this population.
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PMID:[Change in iron metabolism as affected by ionizing radiation]. 814 19

Nephrotoxic lesions induced by cisplatin in rats are characterized by acute tubular necrosis in the outer stripe of the medulla. The purpose of this study was to examine the potential role of changes in metal binding proteins, and iron and copper content in urine and renal tissue in cisplatin-induced nephrotoxicity. Cisplatin was administered intravenously to groups of 20 rats at single doses of 0, 1, 2.5, and 5 mg/kg and rats were sacrificed at 1, 2, 3 and 6 days after treatment. Increased serum BUN and creatinine were observed at a dose of 5 mg/kg cisplatin on day 2 through day 6. Increased urinary copper excretion coincided with necrosis and increased BUN and creatinine on day 3 in the high-dose group. Evidence of renal injury was apparent histologically as karyomegaly at all dose levels as early as 48 hours after injection of cisplatin, prior to increases in urinary copper levels. No change in the distribution of metal binding proteins (transferrin, ferritin, ceruloplasmin, and metallothionein) evaluated by immunohistochemical staining, was seen. Based upon these results, it is unlikely that changes in metal excretion play a primary role in cisplatin-induced nephrotoxicity however, changes in nuclear function indicated by karyomegaly may be involved in early renal injury.
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PMID:Assessment of the possible role of iron and copper in cisplatin-induced nephrotoxicity in the rat. 816 68

Mammalian ferritins are 24-meric proteins composed of variable proportions of H and L-subunits. The L-chain, in contrast to the H-chain, lacks detectable ferroxidase activity, and its role in ferritin iron incorporation is unclear. In this study, apoferritins were subjected to iron loading with large iron increments to favour spontaneous iron hydrolysis. The homopolymers of the wild-type H-chain, and of a mutant H-chain with an inactivated ferroxidase centre, formed massive protein aggregates, while the L-chain homopolymers remained mostly soluble. The difference between H and L-ferritins was not related to the rate of iron oxidation or to the presence of preformed iron cores. Heteropolymers were constructed in vitro by co-renaturing different proportions of the H-chain with the L-chain or mutant H-chain with an inactivated ferroxidase centre. After loading with high iron increments, protein aggregation of the heteropolymers was reduced when the L-chain content was above 70 to 80%, either in combination with the wild-type H-chain or with the inactivated mutant H-chain. Under acidic conditions (pH 5.5, 1000 Fe atoms per molecule) the heteropolymers with about 20% H and 80% L-chains incorporated three to fourfold more iron into soluble 24-mers than the homopolymers. The data indicate that ferritins with more than 18 L-chains per molecule have the capacity to lower non-specific iron hydrolysis in bulk solution. This property is possibly due to a specific attraction of the incoming oxidized iron into the cavity and may be related to an effect of the L-chain on the cavity microenvironment. It is concluded that under high iron increments the ferritins with high L:H-chain ratios are the most efficient in incorporating iron, and this goes some way to explain why iron storage tissues contain L-rich isoferritins.
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PMID:The role of the L-chain in ferritin iron incorporation. Studies of homo and heteropolymers. 818 40

Nine tumor markers in serum including alpha-fetoprotein (AFP), r-glutamyltranspeptidase (GGT), lactate dehydrogenase (LDH), alpha 1-antitrypsin (alpha 1-AT), total sialic acid (TSA), ferritin (Ft), ceruloplasmin (CP), LDH isoenzymes and GGT isoenzymes were used for differential diagnosis of primary liver cancer. Of 5 measurement data tested by statistics, CP and TSA were close to normal distribution (P > 0.1), GGT, LDH and alpha 1-AT showed skewness distribution or to be close to normal distribution with in transformation (P > 0.1). The results indicated that the determination of the cut-off value should depend on the statistical distribution of data. Analysis of single and dual-combination tests as well as triple analysis with sequential progressive screening had been performed to evaluate the predictive value of clinical diagnosis, i.e. the sensitivity, the specificity and the correct diagnosis efficiency. Three predictive values of a single test were lower than what clinical diagnosis raqvest. The dual-combination tests had higher specificity but a lower sensitivity. For triple analysis with sequential progressive screening among the liver cancer group (n = 23), the related disease group (n = 44) and the healthy individuals group (n = 40), the correct diagnosis efficiency was 95%, 97.3% and 100%, respectively. This suggests that the method described here has potential value in clinical practice.
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PMID:[Evaluation of detecting 9 tumor markers in serum for diagnosis of primary liver cancer]. 820 Feb 80

The investigation of cell composition and different biochemical parameters (ceruloplasmin, lactate dehydrogenase, aldolase, ferritin, beta-2-microglobulin) in cerebrospinal fluid has been performed in 37 patients with chronic myeloid leukemia at different clinicohematological stages. The age of the patients ranged from 16 to 67 years. CNS involvement has been diagnosed in 8 (21.6%) patients by clinical and cytological criteria and in 5 (13.5%) patients on the basis of changes in liquor cytograms and in biochemistry. Morphological substrate of leukemic infiltration may be represented by blast cells and cells of granulocytic line of all stages of differentiation. Direct correlation has been established between ferritin and beta-2-microglobulin levels in liquor and its cytological patterns. This permits a conclusion on possible usage of liquor concentration of beta-2-microglobulin and ferritin measurements as additional tests in the diagnosis of neuroleukemia in chronic myeloid leukemia.
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PMID:[The cytological and biochemical aspects of studying the cerebrospinal fluid in patients with chronic myeloleukemia]. 821 76


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