Effect Of Ferric Ions Research Articles

Effect of Ferrous Ion on Tyrosine Hydroxylase of Bovine Adrenal Medulla

Abstract We have studied the effect of Fe2+ on a partially purified tyrosine hydroxylase, prepared after solubilizing with trypsin the crude enzyme sedimented from bovine adrenal medulla homogenate. An approximately 2-fold activation was consistently observed following preincubation of the enzyme with Fe2+ and mercaptoethanol in pH 8.6 Tris buffer. In addition to activating freshly prepared enzyme, the preliminary incubation step restored almost fully the activity of purified tyrosine hydroxylase preparations that had lost 80 to 90% of their activity upon standing overnight at room temperature in pH 6.0 buffer. Catalase or peroxidase could replace Fe2+ in the enzyme assay per se, indicating that the effect of Fe2+ in this step was probably due to its ability to remove H2O2. However, Fe2+ appeared to be specifically required in the activation step; it could not be replaced by catalase, peroxidase, or cations other than Fe2+, either in the presence or absence of mercaptoethanol. Mercaptoethanol could not be replaced in the activation step by glutathione, cysteine, dithiothreitol, or ascorbic acid. These studies indicate that Fe2+, under appropriate conditions, affects tyrosine hydroxylase in a unique manner.

Stress Corrosion Cracking of AISI 4340 Steel Foil in Aqueous Hydrochloric Acid Solutions. Effect of Ferric Ion.

Abstract The susceptibility of AISI 4340 steel foil in aqueous solutions containing hydrochloric acid to stress corrosion cracking (SCC) is increased by ferric ions. Since the reaction between stannous and ferric ions is known to be rapid and complete, the exceptional behavior of stannous ion in inhibiting SCC under these conditions is probably due to the reduction of the ferric ion concentration arising from corrosion of the steel.

The effect of ferric ion on phycocyanin fluorescence

Phycocyanin is demonstrated to interact specifically with ferric ion, accompanied by a time-dependent quenching of phycocyanin fluorescence. The absorption spectrum of phycocyanin is unaffected by complexing with ferric ion. Ferrous ion and several other transition metal ions do not complex with phycocyanin in a similar manner. Studies of electron transport through chlorophyll-containing bileaflet membranes have shown that phycocyanin acts to direct electron transport in a unidirectional fashion. It is postulated that the ferric ion-phycocyanin complex is responsible for this newly observed property of phycocyanin.

The radiation chemistry of aqueous solutions of ferric ethylenediamine tetraacetate

Aqueous solutions of ferric ethylenediamine tetraacetate (F) at pH 1 were irradiated with X-rays both in the presence and in the absence of dissolved oxygen. Radiolytic yields of decomposition of F were determined. Formaldehyde and ferrous ion were also detected amongst the radiolysis products. It has been concluded that the radiolysis is initiated by attack both at the ligand and at the central metal ion of the metal chelate by the free radicals derived from water. A reaction mechanism for the radiolytic degradation of F in aqueous solution has been described. Effects of ferrous ion and methanol on the course of radiolysis were also investigated. From such competition kinetic studies the ratios of the rate constants k OH+Fe 2+ k OH+F and k OH+F k OH+CH 3 OH were found to be 0·48 and 1·7 respectively.

On the Autoxidation of L-Ascorbic Acid and Erythorbic Acid in Acid Solution

When 3×10-3 M L-ascorbic acid (AA) and erythorbic acid (EA) in 50ml of 3.6×10-3 M HCl solution (pH 2.3) containing 3×10-3 M Fe2 (SO4)3 were treated in the oxygen gas flow at a rate Of 3.3ml/sec. at 25°C, the amounts of remained AA and EA after 20min were 79.6 (±2)% and 3.7 (±0.5)% of the initial amounts respectively.The effect of ferric ion on the decomposition of AA and EA was remarkable and accelerated definitely by lowering the pH value to 1.4.The rate of the decomposition of these acids was also affected to some extent by the presence of neutral salts in the reaction mixture.The difference of the decomposition rate between AA and EA is so definitely and highly reproduciable that a potential of a new method of simultaneous determination of these acids within the level of 2.5×10-3 to 3.5×10-3 M was suggested.

The Effect of Ferrous Ion in the Peroxide Initiation of Vinyl Polymerisation on Cellulose

An effective method of initiating graft polymerisation on cellulose utilises the hydrogen peroxide–ferrous ion redox system, in which the ferrous ion component is held predominantly within the cellulose fibres. The method was first used by Landells and Whewell1, and it has now been demonstrated that the success of their procedure depends on ion‐exchange between cellulose and ferrous ion. It has also been shown that the presence of ferrous ion in the cellulose fibres leads to a decrease in the rate of formation of homopolymer and an increase in grafting efficiency. The polymerisation of methyl methaerylate and of styrene by hydrogen peroxide has been shown to be accelerated by the presence of cellulose.

The Anodic Oxidation of Iron in a Neutral Solution: II . Effect of Ferrous Ion and pH on the Behavior of Passive Iron

The anodic polarization curve, the static passive potential, and the behavior of the decay of the polarized passive potential of iron were examined in neutral boric acid/borate solutions with and without Fe++ ion addition. It was found that the passivation potential is a function of the [Fe++] and pH and corresponds to the equilibrium potential of the reaction of . The polarized passive potential in the steady state is related to a pseudoequilibrium potential that corresponds to a higher defect concentration in the oxide surface and to a lower [Fe++] at the oxide/solution interface. The potential gradient across the film appears to be very small. The decay of the polarized passive potential on open circuit is explained as due mainly to the change in the defect‐concentration and consequently of the film composition at the oxide/solution interface either by the outward migration of iron through the film or by the reaction with Fe++ ion in solution when the latter had been added or supplied by a small amount of self‐corrosion.

Effect of ferric ion on the ?-ray induced oxidation of ferrous ion

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The effect of ferrous ions on the formation of toxin and porphyrin by a strain of Corynebacterium diphtheriae.

The effect of the iron concentration in the medium on the concentration of toxin and coproporphyrin in the culture filtrate of a strain of Corynebacterium diphtheriae has been found to differ quantitatively from that previously reported in the case of the P.W. 8 strain. Only 50-60% of the iron present in the medium, at all concentrations tested, was recoverable from the organisms. Of the total iron present in the medium, only 9% was found to be present in the organisms as a haem complex capable of measurement as its pyridine haemochromogen. On the basis of their iron contents protohaemin and iron coproporphyrin III are less active than ferrous sulphate in their effect on toxin yield. These findings do not support the hypothesis that diphtheria toxin is the protein moiety of the cytochrome b of the cell.