Equilibrium and kinetic studies of deuteroferrihaem {chloro[dihydrogen-3,7,12,17- tetramethyl-2,18-porphinedipropionato(2–)]iron(<scp>III</scp>)} dimerization

Jones, Peter; Prudhoe, Kenneth; Brown, Stanley B.

doi:10.1039/dt9740000911

Cited by 17 publications

(19 citation statements)

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“…Again, it should be emphasized that these values reflect an order ofmagnitude rather than precise data. However, it is noteworthy that the k+1 values are very similar to the accurate values obtained by Pasternack et al (1972) for synthetic porphyrins and by Jones et al (1974) for deuteroferrihaem. In all of these dimerizations, the values of k+1 are virtually the same and approach the diffusion-controlled value.…”

Section: Kinetic Resultssupporting

confidence: 80%

“…153 tion of the micelle. This contrasts with the behaviour of deuteroferrihaem, when dimerization increased with increasing temperature (Jones et al, 1974). ThepH-dependence (shown forhaematoporphyrin) was also significant.…”

Section: Temperature Ionic Strength Andph Variationcontrasting

confidence: 74%

“…Dimerization has been found to occur in aIl the systems studied (Brown et al, 1970a;Fleischer et al, 1971;Jones et al, 1974;Katz et al, 1963) although the earlier evidence for more extensive aggregation, reviewed by Lemberg & Legge (1949), has not been substantiated. For the naturally occurring protoferrihaem and the related deuteroferrihaem, dimerization occurs according to the equation: K 2M -2 D+H+ (Brown et al, 1970a) where M and D represent monomeric and dimeric ferrihaem respectively.…”

mentioning

confidence: 92%

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Equilibrium and kinetic studies of the aggregation of porphyrins in aqueous solution

Brown

Shillcock

Jones

1976

Biochemical Journal

228

118

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An investigation of the behavior of protoporphyrin IX, deuteroporphyrin IX, haematoporphyrin IX and coproporphyrin III in aqueous solution revealed extensive and complex aggregation processes. Protoporphyrin appears to be highly aggregated under all conditions studied. At concentrations below 4 muM, aggregation of deutero-, haemato- and coproporphyrin is probably restricted to dimerization. At approx. 4muM each of these three porphyrins exhibits sharp changes in spectra consistent with a "micellization" process to form large aggregates of unknown size. This critical concentration increases with increasing temperature and pH, but is not very sensitive to variation in ionic strength. Temperature-jump kinetic studies on deuteroporphyrin also imply an initial dimerization process, the rate constants for which are comparable with those for various synthetic porphyrins, followed by a further extensive aggragation. The ability of a particular porphyrin to dimerize appears to parallel that of the corresponding iron(III) complexes (ferrihaems), although it is thought that ferrihaems do not exhibit further aggregation under these conditions.

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Section: Kinetic Resultssupporting

confidence: 80%

Section: Temperature Ionic Strength Andph Variationcontrasting

confidence: 74%

mentioning

confidence: 92%

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Equilibrium and kinetic studies of the aggregation of porphyrins in aqueous solution

Brown

Shillcock

Jones

1976

Biochemical Journal

228

118

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“…For protoferrihaem and deuteroferrihaem the values -of K (which is dimensionless) were found to be 4.5 and 0.034 respectively in 0.033 M-phosphate buffer (KH2PO4/Na2HPO4, I0.1;Brown et al, 1970;Jones et al, 1974). In a study using stopped-flow spectrophotometry, Jones et al (1973) showed that the oxidation of deuteroferrihaem by H202 was much faster than oxidation of protoferrihaem under comparable conditions, consistent with the monomeric species being more reactive.…”

mentioning

confidence: 95%

The role of peroxide in haem degradation. A study of the oxidation of ferrihaems by hydrogen peroxide

Brown¹,

Hatzikonstantinou²,

Herries³

1978

Biochemical Journal

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The oxidation of ferrihaems by H2O2 was studied as a model for haem catabolism. Rates of ferrihaem oxidation were evaluated by using a new computer-based method that measures the loss in catalytic activity of the ferrihaem during oxidation. For protoferrihaem, deuteroferrihaem, coproferrihaem and mesoferrihaem, oxidation proceeded via the monomeric species and no dimer contribution was detectable. The pH-dependence of oxidation was studied in the range 6.5--11. Within experimental error, the data were compatible with an inverse linear dependence on [H+]. This was interpreted in terms of attack by HO2- on monomeric ferrihaem. The specific second-order rate constants for oxidation of monomeric species by HO2- were of the same order of magnitude for all the ferrihaems, and were in the sequence coproferrihaem greater than protoferrihaem greater than mesoferrihaem congruent to deuteroferrihaem. A model is suggested involving formation of a ferrihaem monomerperoxide complex, which may either dissociate with the formation of a peroxidatic intermediate or be involved in an intramolecular oxidation of the ferrihaem. Haem catabolism may occur via the same or a similar intermediate.

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“…1 Studies of these derivatives are complicated by pH-dependent dimer formation whose equilibria and kinetics are, however, well characterized. 2, 3 The rate-limiting step for the reaction of deuteroferrihaem and other derivatives with hydrogen peroxide, peroxy acids, and other oxygen-transfer agents is dependent on the concentration of ferrihaem monomer and that of the peroxide. 4, 5 We have recently described a detailed mechanism for the reaction of deuteroferrihaem and peroxy acids that is consistent with the kinetics, the spectrum of the long-lived intermediate species formed after the rate-limiting step, and the overall stoichiometry.…”

mentioning

confidence: 99%

Reaction of deuteroferrihaem and m-chloroperoxybenzoic acid in surfactant micelles

Davies¹,

Gillitt²

1997

J. Chem. Soc., Dalton Trans.

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Equilibrium and kinetic studies of deuteroferrihaem {chloro[dihydrogen-3,7,12,17- tetramethyl-2,18-porphinedipropionato(2–)]iron(III)} dimerization

Cited by 17 publications

References 0 publications

Equilibrium and kinetic studies of the aggregation of porphyrins in aqueous solution

Equilibrium and kinetic studies of the aggregation of porphyrins in aqueous solution

The role of peroxide in haem degradation. A study of the oxidation of ferrihaems by hydrogen peroxide

Reaction of deuteroferrihaem and m-chloroperoxybenzoic acid in surfactant micelles

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