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 carbohydrate-containing fraction was extracted from the trypanosomatid Crithidia fasciculata by a phenol-water procedure. Ion-exchange chromatography separated this fraction into three components: a polysaccharide which was not retained on the column; RNA which eluted upon addition of salt; and, another polysaccharide which eluted upon addition of detergent. The unretained fraction was shown to be composed solely of D-mannose. The mannan, which was heterodisperse on Sephadex G-100, had an average molecular weight of approx. 14 000 as based on analysis of reducing groups. The detergent-eluted material yielded arabinose and galactose upon acid hydrolysis. The arabinogalactan was excluded from Sephadex G-100 and Sephacryl S-200 molecular sieve columns, suggesting a molecular weight greater than or equal to 200 000. Cell fractionation studies showed the bulk of extractable polysaccharide was associated with a particulate fraction. Further determination of the cellular localization of the polysaccharide was accomplished by employing a specific antiserum prepared from rabbits immunized with the polysaccharide extract. The cell surface localization of the arabinogalactan was demonstrated by cell agglutination studies as well as immunocytochemical techniques using fluorescein and ferritin conjugated antibodies.
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PMID:Polysaccharides of crithidia fasciculata. Identification and partial characterization of a cell surface constituent. 9 71

Non-O1 Vibrio cholerae produced two distinct colony types, designated as opaque and translucent. NRT36S, a clinical isolate shown to be virulent in volunteers, produced predominantly opaque colonies, but translucent colonies appeared on subculture. Opaque variants were recovered exclusively following exposure to normal human serum or animal passage. A nonreverting translucent mutant of NRT36S, JVB52, was isolated following mutagenesis with the transposon Tn5 IS50L::phoA (TnphoA). Only translucent colonies were produced by a nonpathogenic environmental isolate, A5. Electron microscopic examination of the opaque form of NRT36S revealed thick, electron-dense, fibrous capsules surrounding polycationic ferritin-stained cells. The ferritin-stained material around translucent NRT36S or A5 was patchy or absent. JVB52 had a thin but contiguous capsular layer. The amount of ferritin-stained capsular material correlated with the amount of surface polysaccharide determined by phenol-sulfuric acid assay: opaque NRT36S had approximately three times as much polysaccharide as translucent NRT36S or A5 and four times as much as JVB52. The encapsulated, opaque variant of NRT36S was protected from serum bactericidal activity, while translucent non-O1 V. cholerae was readily killed. The encapsulated form also had increased virulence in mice. Our data provide the first indication that non-O1 V. cholerae strains can have a polysaccharide capsule. This capsule may be important in protecting the organism from host defenses and may contribute to the ability of some non-O1 V. cholerae strains to cause septicemia in susceptible hosts.
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PMID:Non-O1 Vibrio cholerae NRT36S produces a polysaccharide capsule that determines colony morphology, serum resistance, and virulence in mice. 131 6

The translation of a small number of mRNAs in mouse SC-1 fibroblasts can be stimulated by cycloheximide, under conditions where the synthesis of most proteins is inhibited. These mRNAs are ordinarily present in small polyribosomes or messenger ribonucleoprotein particles, although the addition of cycloheximide drives them into large (greater than or equal to 5) polysomes. These mRNAs cannot be translated in vitro unless they are extracted with phenol. With such treatment, however, they are translated with normal competitive efficiencies. In iron-poor media, the mRNA for ferritin exhibits several of the distinctive kinetic properties of this class of mRNAs. With iron supplementation, however, ferritin translation appears normal. These observations are consistent with the existence of translational induction/repression systems in eukaryotes. Several types of evidence suggest that repressors may act by interfering with the interaction between mRNAs and limiting translational initiation components.
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PMID:Translational control of gene expression in a normal fibroblast. Characterization of a subclass of mRNAs with unusual kinetic properties. 370 30

The release of iron from ferritin in the presence of benzene metabolites, viz. phenol (P), catechol (CT), hydroquinone (HQ) and superoxide radical generating compounds, viz. pyrogallol (PL), phloroglucinol (PG), phenylhydrazine (PH) or phenylenediamine (PD) was studied in acetate buffer, pH 5.6. Monitoring the formation of the iron-ferrozine complex quantitated the release of iron from ferritin. The presence of P (125 microM) did not result in the release of iron from ferritin, whereas the same concentration of CT, HQ, PL, PH or PD resulted in the release of significant amounts of iron from ferritin and a marginal amount of iron in the presence of PG, CT, HQ, PL, PH or PD concentration and time-dependent increase in iron release from ferritin were observed although the increase was not linear as a function of time and concentration of the compounds studied. The presence of superoxide dismutase inhibited significantly the release of iron from ferritin by CT, HQ, PL, PH or PD. The iron released from ferritin by CT, HQ, PL, PH or PD enhanced lipid peroxidation in rat brain homogenate and released aldehydic products from bleomycin-dependent degradation of DNA and also caused single strand nicks to pUC18 DNA. These studies indicate that CT and HQ, the two principal polyphenolic metabolites of benzene and PL, PH or PD, the superoxide radical generating compounds were capable of reducing ferric iron from ferritin and also mobilizing and releasing iron from ferritin core. The release of iron from ferritin by these compounds is a result of direct reduction of ferritin iron by electron transfer and also reduction via superoxide radical. The release of iron from ferritin by CT and HQ may have toxicological implications in relation to benzene toxicity. The release of iron by superoxide radical generating agents suggests that oxidative stress may play a role as this could lead to disruption of intracellular iron homeostasis.
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PMID:Release of iron from ferritin by metabolites of benzene and superoxide radical generating agents. 1168 19

Ferritin is the main intracellular iron storage protein. The release of iron from ferritin in the presence of a number of phenolic based compounds of nutritional significance was studied at physiological pH. The release of iron was measured by monitoring the formation of the iron(II)-ferrozine complex. The kinetics of this process were studied in Hepes buffer (pH 7.00), at 37 degrees C. The order of ability to remove iron from ferritin is epigallocatechin>gallic acid methyl ester approximately equal to sinapic acid>ferulic acid. The presence of the oxyradical scavenger urea resulted in a slight inhibition in the release of iron from ferritin by both gallic acid methyl ester and epigallocatechin. The ability of each reagent to release iron is interpreted on the basis of their ability to (a) reduce the bound iron and (b) complex the iron with the oxidised form of the phenol, thus mobilising it from the protein. These studies indicate that some phenolic based compounds that have been epidemiologically associated with a negative effect on iron absorption in man, can individually mobilise and release iron from ferritin under suitable conditions.
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PMID:Investigation of the release of iron from ferritin by naturally occurring antioxidants. 1200 51

Oxidative modification of low-density lipoprotein (LDL) and its deleterious effect on endothelium is implicated in the pathogenesis of atherosclerosis. Endothelium responds to such an insult by upregulating the synthesis of heme oxygenase-1 (HO-1) and ferritin. Endothelial cell damage and dysfunction have been observed in patients with chronic kidney disease (CKD) on maintenance hemodialysis (HD). We studied the effect of low-molecular-weight components of uremic plasma on LDL oxidation and LDL-oxidation-provoked endothelial cell reactions, such as the induction of cytotoxicity and the upregulation of cell-protective HO-1 and ferritin. Plasma ultrafiltrate (molecular weight<5000 Da) from CKD patients on HD or when treated conservatively exhibited a pronounced inhibition on heme-mediated oxidative modification of LDL. Endothelial cell cytotoxicity provoked by LDL oxidation was also attenuated by plasma ultrafiltrate from CKD patients. During HD treatment, a dramatic drop occurred in the retardation of oxidative reactions, and a loss of endothelial cytoprotection exerted by plasma ultrafiltrate was noted. The upregulation of HO-1 and ferritin in response to oxidative stress of LDL was blunted by uremic plasma ultrafiltrate that was released by the end of HD. The decreased antioxidant capacity of ultrafiltrate after HD occurred as a consequence of the intradialytic removal of L-ascorbic acid, uric acid, bilirubin, 3-indoxyl sulfate, indoxyl-beta-D-glucuronide, p-cresol, and phenol. Intradialytic removal of L-ascorbic acid, uric acid, bilirubin, 3-indoxyl sulfate, indoxyl-beta-D-glucuronide, p-cresol, and phenol increases the risk of LDL oxidation and subsequent endothelial cell damage, which underlines the importance of activation of cytoprotective HO-1 and ferritin in endothelium.
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PMID:Hemodialysis reduces inhibitory effect of plasma ultrafiltrate on LDL oxidation and subsequent endothelial reactions. 1681 Feb 93

Continuum solvation methods are frequently used to increase the efficiency of computational methods to estimate free energies. In this paper, we have evaluated how well such methods estimate the nonpolar solvation free-energy change when a ligand binds to a protein. Three different continuum methods at various levels of approximation were considered, viz., the polarized continuum model (PCM), a method based on cavity and dispersion terms (CD), and a method based on a linear relation to the solvent-accessible surface area (SASA). Formally rigorous double-decoupling thermodynamic integration was used as a benchmark for the continuum methods. We have studied four protein-ligand complexes with binding sites of varying solvent exposure, namely the binding of phenol to ferritin, a biotin analogue to avidin, 2-aminobenzimidazole to trypsin, and a substituted galactoside to galectin-3. For ferritin and avidin, which have relatively hidden binding sites, rather accurate nonpolar solvation free energies could be obtained with the continuum methods if the binding site is prohibited to be filled by continuum water in the unbound state, even though the simulations and experiments show that the ligand replaces several water molecules upon binding. For the more solvent exposed binding sites of trypsin and galectin-3, no accurate continuum estimates could be obtained, even if the binding site was allowed or prohibited to be filled by continuum water. This shows that continuum methods fail to give accurate free energies on a wide range of systems with varying solvent exposure because they lack a microscopic picture of binding-site hydration as well as information about the entropy of water molecules that are in the binding site before the ligand binds. Consequently, binding affinity estimates based upon continuum solvation methods will give absolute binding energies that may differ by up to 200 kJ/mol depending on the method used. Moreover, even relative energies between ligands with the same scaffold may differ by up to 75 kJ/mol. We have tried to improve the continuum solvation methods by adding information about the solvent exposure of the binding site or the hydration of the binding site, and the results are promising at least for this small set of complexes.
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PMID:Accurate predictions of nonpolar solvation free energies require explicit consideration of binding-site hydration. 2172 37

We present a combination of semiempirical quantum-mechanical (SQM) calculations in the conductor-like screening model with the MM/GBSA (molecular-mechanics with generalized Born and surface-area solvation) method for ligand-binding affinity calculations. We test three SQM Hamiltonians, AM1, RM1, and PM6, as well as hydrogen-bond corrections and two different dispersion corrections. As test cases, we use the binding of seven biotin analogues to avidin, nine inhibitors to factor Xa, and nine phenol-derivatives to ferritin. The results vary somewhat for the three test cases, but a dispersion correction is mandatory to reproduce experimental estimates. On average, AM1 with the DH2 hydrogen-bond and dispersion corrections gives the best results, which are similar to those of standard MM/GBSA calculations for the same systems. The total time consumption is only 1.3-1.6 times larger than for MM/GBSA.
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PMID:A semiempirical approach to ligand-binding affinities: dependence on the Hamiltonian and corrections. 2239 76

Lead in liver, spleen and kidney of poisoned cattle is bound to substances containing ferric hydroxide. In liver and kidney the smaller amount of lead is sorbed by ferritin, the greater amount by insoluble ferric hydroxide. In the spleen ferritin and insoluble ferric hydroxide contain approximately the same amount of lead. The insoluble ferric hydroxide particles could be concentrated by digestion of insoluble liver proteins with phenol. They were not identical with hemosiderin. The sorption of lead ions and of other metal ions to ferritin and ferric hydroxide was investigated in vitro. Lead sorption is preferred over the sorption of other metal ions. Reaction of metal ions with the protein shell of ferritin occurred only with copper ions. The sorbed metal ions could be split from ferritin by high concentrations of other metal ions and strongly by hydrogen ions. It seems, that lead binding disturbs the storage of iron in tissues in lead poisoning.
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PMID:[Not Available]. 2418 2

We tested different approaches to including the effect of binding-site water molecules for ligand-binding affinities within the MM/GBSA approach (molecular mechanics combined with generalised Born and surface-area solvation). As a test case, we studied the binding of nine phenol analogues to ferritin. The effect of water molecules mediating the interaction between the receptor and the ligand can be studied by considering a few water molecules as a part of the receptor. We extended previous methods by allowing for a variable number of water molecules in the binding site. The effect of displaced water molecules can also be considered within the MM/GBSA philosophy by calculating the affinities of binding-site water molecules, both before and after binding of the ligand. To obtain proper energies, both the water molecules and the ligand need then to be converted to non-interacting ghost molecules and a single-average approach (i.e., the same structures are used for bound and unbound states) based on the simulations of both the complex and the free receptor can be used to improve the precision. The only problem is to estimate the free energy of an unbound water molecule. With an experimental estimate of this parameter, promising results were obtained for our test case.
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PMID:Effect of explicit water molecules on ligand-binding affinities calculated with the MM/GBSA approach. 2486 80


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