Showing papers on "Ferric published in 1976"

Isolation of Monoferric Phytate from Wheat Bran and its Biological Value as an Iron Source to the Rat

Abstract: The objectives of the study were to isolate and chemically characterize the iron in wheat and to determine the biological availability to the rat of the iron as the purified complex(es). Hard wheat bran contained no butanol extractable or water extractable iron, but approximately 60% of the iron was extracted by 1 to 1.2 M NaCl or ammonium acetate solution. This salt extractable iron complex was purified and identified as monoferric phytate. The purified monoferric phytate was soluble in water. Synthetic monoferric phytate was prepared from sodium phytate and ferric chloride and determined to have spectral characteristics and gel filtration chromatography behavior identical to the complex isolated from wheat bran. The butanol-water-salt extracted bran residue contained no detectable phytate and an as yet uncharacterized form of iron. The biological availability of the iron to the rat was determined by a hemoglobin depletion-repletion bioassay. The relative biological value of the iron as monoferric phytate, either isolated from wheat bran or the synthetic product, was equal to the reference compound, ferrous ammonium sulfate. In contrast, the biological availability of the iron in the bran residue was significantly lower and the low biological availability of an insoluble form of ferric phytate was confirmed. It is concluded that the major portion of the iron in wheat is monoferric phytate and has a high biological availability to the rat. Monoferric phytate in bran may be bound to cationic sites of proteins or other cellular components and utilization of the iron may be through solubilization of the monoferric phytate by ion exchange type mechanism rather than by hydrolysis of the phytate as has been postulated.

Mechanisms of siderophore iron transport in enteric bacteria.

Abstract: Uptake of 55Fe- and 3H-labeled siderophores and their chronic analogues have been studied in Salmonella typhimurium LT-2 and Escherichia coli K-12. In S. typhimurium LT-2, at least two different mechanisms for siderophore iron transport may be operative. Uptake of 55Fe- and 3H-labeled ferrichrome and kinetically inert lambda-cis-chromic [3H]deferriferrichrome by the S. typhimurium LT-2 enb7 mutant, which is defective in the production of its native siderophore, enterobactin, appears to occur by two concurrent mechanisms. The first mechanism is postulated to involve either rapid uptake of iron released from the ferric complex by cellular reduction without penetration of the complex or ligand or dissociation of the complex and simultaneous uptake of both ligand and iron coupled with simultaneous expulsion of the ligand. The second mechanism appears to consist of slower uptake of the intact ferric complex.

Crystal structure of green rust formed by corrosion of cast iron

Abstract: THE principal solid corrosion products of iron in water are magnetite and hydrated forms of ferric oxide, depending on the degree of oxidation. The occurrence of intermediate products, termed green rusts, was reported by Keller1 in 1948, since when the formation and decomposition of these compounds, precipitated from aqueous solution by controlled oxidation of ferrous hydroxide, have been extensively studied2–5. It has been proposed2,3 that specific anions are incorporated in the crystal structure of some green rusts, although no substantial evidence has been found to confirm this. A number of green rusts have been classified crystallographically3 as follows: first, rhombohedral green rusts I (GRI) formed in Cl−, SO42− and Br− solutions and (second), hexagonal green rust II (GRII) formed only in SO42− solutions by decomposition of GRI. The interrelationships between the various products involved in the oxidation of ferrous hydroxide have been summarised by Misawa et al.5 In this paper a preliminary account is given of the crystal structure of a rhombohedral green rust formed by corrosion of iron which, although of similar unit cell dimensions to GRI, differs structurally from those previously reported.

Characterization of partially neutralized ferric chloride solutions

Abstract: Ferric hydroxy polycations formed in a range of partially neutralized ferric nitrate solutions have been characterized using electron microscope and density gradient ultracentrifugation techniques. In all solutions the initial polycations were discrete spheres 1.5–3.0 nm diameter. From these spheres, rods composed of 2–5 spheres were formed during ageing. These rods aged by two distinct processes which depended on the solution conditions. In one the rods remained the same length and aggregated with time to form extensive raft-like arrays of rods. The spheres within the rods slowly coalesced and goethite was formed. In the other process the rods increased in length but not width and did not form “rafts” Goethite was formed during this increase in length. On extended ageing, some of the rods linked and coalesced to give lath shaped goethite crystals. The first process was favored by high ionic strength and/or high ferric concentrations and the second by a lower ionic strength and/or concentration.

The influence of colloidal organic matter on iron and iron-phosphorus cycling in an acid bog lake1

Abstract: The relationship between iron and phosphorus and the relationship of these elements to colloidal organic matter (COM ) was studied in a meromictic acid bog lake by chemical characterization, filtration and in situ dialysis, and in situ experiments with labeled components. Bathophenanthroline ( BPN ) rcactivc ferrous iron existed in true solution ( dialyzable ) in constantly anaerobic monimolimnetic water; iron was of colloidal size. in the aerobic epilimnion reactive ferric Intermediate depths, oxygenated only during spring, contained two forms of ferrous iron reactive to BPN: dialyzable ferrous iron (Fe’+) and colloidal Fe( II ) which may have originated through in situ reduction of colloidal reactive ferric iron and may be present as a COM-Fe”’ complex. The amount of COM influenced the fate of dialyzable Fe” (92% of total iron) and dialyzable POC-P (85% of total phosphorus) present in anaerobic strata before aeration. Aeration with soluble organic matter present (COM absent) resulted in the formation of colloidal nonreactive ferric iron (84% of total iron) and %0/o colloidal PO.I-P, while aeration with 20 mg liter-’ COM resulted in only 36% colloidal, nonreactive ferric iron and 19% colloidal PO.i-P. COM apparently masks the cationic propertics of colloidal ferric iron and retards the formation of nonreactive Fc( III), allowing most of the Pot-P to remain free in solution and biologically available.

Oxidation of acetic acid solutions in a trickle-bed reactor

Abstract: Rates of oxidation of dilute, aqueous solutions of acetic acid were measured at 252° to 286°C and 67 atm in liquid full and trickle-bed reactors packed with ferric oxide catalyst particles. Predicted global rates and conversions indicated that localized vaporization and liquid channeling could affect trickle-bed performance.

Vyredox — In Situ Purification of Ground Water

Abstract: The abundance and relative purity of ground water guarantees its increase in usage. In some localities, the content of iron and manganese in ground water is so high that these metals must be removed before the water can be used for drinking or industrial purposes. Iron occurs in two states of oxidation in nature–the divalent (ferrous) and trivalent (ferric) forms. The Vyredox method developed in Finland and used now also in Sweden and some other countries oxidizes the ferrous ion, which is soluble in water, to the ferric ion, which is insoluble, before the water enters the well. The Vyredox method achieves a high degree of oxidation in the strata around the well. The method makes use of iron-oxidizing bacteria and aeration wells. A number of aeration wells are placed in a ring around the supply well. Water is forced down the aeration wells but first it is degassed and then enriched with oxygen. The oxygen-rich water provides a suitable habitat for the iron-oxidizing bacteria which assist in the oxidation of ferrous iron. The process must be repeated at specific time intervals to avoid further increases of iron content. The process of precipitating iron in the aquifer has only a slight effect on aquifer permeability. Cloggage of the aquifer surrounding the well should not occur for a period many times longer than the life span of a typical well.

Effect of iron on the biodegradation of petroleum in seawater.

Abstract: The biodegradation of South Louisiana (SL) crude oil and the effects of nitrogen, phosphorus, and iron supplements on this process were compared in a polluted (10,900 oil degraders per liter) and in a relatively clean (750 oil degraders per liter) littoral seawater sample taken along the New Jersey coast. Without supplements, the biodegradation of SL crude oil was negligible in both seawater samples. Addition of nitrogen and phosphorus allowed very rapid biodegradation (72% in 3 days) in polluted seawater. Total iron in this seawater sample was high (5.2 muM), and the addition of iron did not increase the biodegradation rate further. In the less polluted and less iron-rich (1.2 muM) seawater sample, biodegradation of SL crude oil was considerably slower (21% in 3 days) and the addition of chelated iron had a stimulating effect. Ferric octoate was shown to have a similar stimulating effect on SL crude oil biodegradation as chelated iron. Ferric octoate, in combination with paraffinized urea and octylphosphate, is suitable for treatment of floating oil slicks. We conclude that spills of SL crude and similar oils can be cleaned up rapidly and efficiently by stimulated biodegradation, provided the water temperatures are favorable.

Reduction and Oxidation of Fe3+ in Dioctahedral Smectites—2: Reduction with Sodium Sulphide Solutions

Abstract: Reaction with Na2S solutions at high pH led to almost complete, reversible reduction of iron in montmorillonite, whereas the structural iron of nontronite persisted in the ferric form. Concentrated Na2S solutions caused severe corrosion of nontronite and extracted appreciable amounts of iron, which was precipitated as sulphides. In contrast the morphology of montmorillonite was preserved and only very minor amounts of iron were extracted. These differences were attributed to the high concentration of Fe-OH-Fe groups in nontronite, which are unstable on reduction. The difference between Na2S and other reducing agents is discussed.

Five-coordinate iron-porphyrin as a model for the active site of hemoproteins. Characterization and coordination properties.

Abstract: Preparation of iron(III)-deuteroporphyrin 6(7)-methyl ester, 7(6)-(histidine methyl ester) by coupling histidine methyl ester to deuterohemin has been performed using the mixed carboxylic/carbonic-acid-anhydride method. This compound, which is very soluble in various organic solvents, can be considered as a prosthetic group model for the active site of five-coordinate hemoproteins. In the oxidized state a basic, a neutral or an acid form can be isolated. The basic and acid forms are monomeric at all concentrations. The neutral form is found dimeric in concentrated solutions while it is monomeric at low concentration. The coordination state of iron in these various species is investigated. The neutral form reacts with ligands, such as nitrogenous organic bases, leading to six-coordinate well-known hemichromes which exhibit low-spin electron spin resonance (ESR) spectra. The reaction of anionic ligands, such as F-, CN-, NO-2 and N-3, with the neutral form model leads to unsymmetrical six-coordinate complexes whose optical and ESR spectra are similar to those of synthetic deuteromyoglobin. In benzene, toluene or dichloromethane solutions iron (II)-deuteroporphyrin 6(7)-methyl ester, 7(6)-histidine methyl ester), obtained from ferric forms by heterogeneous reduction with aqueous dithionite, exhibits an optical spectrum characteristic of a five-coordinate high-spin ferrous complex. At low temperature important spectral modifications are observed indicating a dimeric association. At room temperature it binds one nitrogenous base molecule leading to the well-known hemochrome. It reacts also with carbon monoxide with a very high affinity constant (4.5 X 10(8) M-1), comparable to that of the isolated human hemoglobin alpha and beta chains, but much higher than the values reported for other various models, suggesting that the side-chain length bearing the fifth ligand may have an important influence upon the reactivity of the sixth position of the iron ion. At low temperature in toluene or dichloromethane, this compound reversibly binds oxygen without oxidation of the iron ion while oxidation occurs at room temperature. The significance of these results is discussed in relation with the local environment, the electronic nature of the base and the immobilization of the heme group in hemoproteins.

Iron absorption by humans from hemosiderin and ferritin, further studies.

Abstract: Iron absorption from hemosiderin and ferritin biosynthetically labeled with radioactive iron has been studied in 61 subjects. The geometrical mean iron absorption from hemosiderin in both normal and iron deficient subjects was 3.4%. Its mean absorption ranged from 1.9% in normal subjects to 4.7% in subjects with moderate iron deficiency and 7.3% in subjects with marked iron deficiency. The iron absorption from hemosiderin was markedly increased when it was administered with ascorbic acid or liver. The absorption of iron from hemosiderin when hemosiderin and wheat were consumed in a meal, was lower than the absorption from wheat. Iron from liver ferritin and liver hemosiderin were less absorbed in this study than that previously reported for liver hemoglobin. The studies presented here support the possibility that ferritin and hemosiderin form an iron pool different from the non-heme pool formed by vegetal iron, egg iron and ferric and ferrous salts.

Hydrometallurgical process for recovering copper and other metal values from metal sulphides

Abstract: A hydrometallurgical process for the separate recovery of non-ferrous, ferrous, and precious metal values and sulfur from metal sulfide ore concentrates by leaching of metal sulfides with a lixiviant containing ferric chloride, cupric chloride and chlorine, precipitating cuprous chloride from the leach solution with butadiene, separating and decomposing the formed addition compound to recover the cuprous chloride, oxidizing and hydrolyzing the cuprous chloride to precipitate cupric oxychloride, converting the cupric oxychloride to cupric oxide, and reducing the cupric oxide with hydrogen for the recovery of copper. The leach residue is treated for the recovery of elemental sulfur and gold. Brine solution resulting from the conversion of cupric oxychloride to cupric oxide is electrolyzed for the production of sodium hydroxide for the cupric oxychloride conversion, hydrogen for the cupric oxide reduction and chlorine, which is partly used in the recovery of gold and partly recycled to the concentrate leach. Silver is recovered as silver iodide from the mother liquor from the cuprous chloride precipitation with butadiene. A portion of the solution from the silver recovery is treated for recovery of Cu, Zn, Co and Ni, and the remaining portion and residual solution from Cu, Zn, Co and Ni recovery are treated with oxygen at elevated temperature and pressure for the regeneration of ferric chloride and precipitation of excess iron as anhydrous ferric oxide.

Fungal ornithine esterases: relationship to iron transport.

Abstract: Extracts of Fusarium roseum (ATCC 12822) contain an enzyme which hydrolyzes the ornithine ester bonds of fusarinine C, a cyclic trihydroxamic acid produced by this organism The methyl ester of Ndelta-dinitrophenyl-L-ornithine is also a substrate for the enzyme, and an assay was devised using this substrate The enzyme exhibits a sharp maximum of activity at pH 75 and is extremely temperature sensitive It is strongly inhibited by HgCl2 and p-chloromercuribenzoate, and it is competitively inhibited by Ndelta-dinitrophenyl-D-ornithine methyl ester (Ki = 03mM) Methyl esters of glycine, L-alanine, dinitrophenyl-L-alanine, dinitrophenyl-beta-alanine, and Ndelta-dinitrophenyl-Nalpha-acetyl-L-ornithine are not substrates, although Nepsilon-dinitrophenyl-L-lysine methyl ester is as effective as the ornithine derivative Nonspecific lipases do not hydrolyze ornithine esters, nor does trypsin The three ester bonds of fusarinine C are progressively hydrolyzed by the enzyme to eventually yield the monomer, fusarinine The ferric chelate of fusarinine C is not hydrolyzed An enzyme from Penicillium sp was isolated with identical properties toward Nbeta-dinitro-phenyl-L-ornithine methyl ester as substrate It also hydrolyzes N,N',N"-triacetylfusarinine C, a cyclic trihydroxamate containing Nalpha-acetylornithine ester bonds, which is produced by this organism This substrate is hydrolyzed to Nalpha-acetylfusarine In contrast to the Fusarium enzyme, this enzyme is fully active toward the ferric trihydroxamate chelate However, replacement of iron by aluminum leads to a completely inactive substrate Production of the enzyme is severely suppressed by iron in the growth medium It is proposed that these specific ornithylesterases provide a mechanism of cellular iron release by hydrolysis of the ferric ionophores, and that an iron-exchange step occurs prior to, and is a prerequisite for, hydrolysis of the ester bonds