Haemoglobulin catabolism: the role of ferrihaems in studies of the degradation pathway (Short Communication)

Brown, Nigel A.; King, Rhodri; Shillcock, M. E.; Brown, Stanley B.

doi:10.1042/bj1370135

Cited by 16 publications

(12 citation statements)

References 11 publications

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“…in solution [58]. By virtue of being the main catalytic element in reactions involving monomeric and dimeric ferrihemes, the monomeric ferric heme is more easily broken down during the catabolism of hemoglobins [59] and so introduces more reactive elements that can propagate reactive oxygen species (ROS) production.…”

Section: Discussionmentioning

confidence: 99%

Cation Modulation of Hemoglobin Interaction with Sodium n-Dodecyl Sulfate (SDS). I: Calcium Modulation at pH 7.20

Chilaka

Nwamba

Moosavi-Movahedi

2010

Cell Biochem Biophys

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A comparative denaturation of HbA and HbS in the R states using sodium n-dodecyl sulfate (SDS) was carried out at pH 7.20 in the presence and absence of Calcium (0-40 μM) and monitored by UV-Vis spectrophotometry in the range of 250-650 nm. In the HbS spectra, the calcium alone caused little or no perturbation of the aromatic region but caused a decrease in oxygen affinity when compared to the HbA. The combinations of [SDS] and [Ca] perturbed the HbS the most, relative to the individual spectra of the [SDS] and [Ca]. However, the presence of Ca appeared to diminish the adverse effects of the SDS on HbA. The denaturation pathway of the HbA involved mainly the formation of heme dimers and some ferryl heme species. For the HbS, heme monomers and a large amount of ferryl species were formed. It is suggested that the greater monomer species formed by the HbS denaturation pathway would result in both Fenton and enhanced enzymatic reactions, compared to the dimer. This could lead ultimately to the formation of ferryl radicals. Thus, at physiological pH for the HbS, the Ca-SDS interaction increases the tendency for protein denaturation in comparison to the HbA.

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Section: Discussionmentioning

confidence: 99%

Cation Modulation of Hemoglobin Interaction with Sodium n-Dodecyl Sulfate (SDS). I: Calcium Modulation at pH 7.20

Chilaka

Nwamba

Moosavi-Movahedi

2010

Cell Biochem Biophys

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“…However, the binding of GSH to the Fe atom of heme is similar to that of Cys (Bayer et al, 1974), which does not enhance heme inhibition of ALA synthesis. To examine further a possible role for GSH in increasing the effective heme concentration by breaking heme dimers, two agents that have been reported to break heme dimers, imidazole (O'Carra, 1975) and BSA (Brown et al, 1974), were tested for the ability to influence heme inhibition of ALA synthesis. Imidazole (1 mM) had no effect on heme inhibition, nor did it affect ALA-synthesizing activ- ity in the absence of heme (Table I).…”

Section: Resultsmentioning

confidence: 99%

Heme Inhibition of [delta]-Aminolevulinic Acid Synthesis Is Enhanced by Glutathione in Cell-Free Extracts of Chlorella

et al. 1993

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In plants, algae, and many bacteria, the heme and chlorophyll precursor, 6-aminolevulinic acid (ALA), is synthesized from glutamate in a reaction involving a glutamyl-tRNA intermediate and requiring ATP and NADPH as cofactors. In particulate-free extracts of algae and chloroplasts, ALA synthesis is inhibited by heme. lnclusion of 1.0 mM glutathione (CSH) in an enzyme and tRNA extract, derived from the green alga Chlorella vulgaris, lowered the concentration of heme required for 50% inhibition approximately 10-fold. The effect of CSH could not be duplicated with other reduced sulfhydryl compounds, including mercaptoethanol, dithiothreitol, and cysteine, or with imidazole or bovine serum albumin, which bind to heme and dissociate heme dimers. Absorption spectroscopy indicated that heme was fully reduced in incubation medium containing dithiothreitol, and addition of CSH did not alter the heme reduction state. Oxidized CSH was as effective in enhancing heme inhibition as the reduced form. Co-protoporphyrin IX inhibited ALA synthesis nearly as effectively as heme, and 1.0 mM CSH lowered the concentration required for 50% inhibition approximately 10-fold. Because CSH did not influence the reduction state of heme in the incubation medium, and because CSH could not be replaced by other reduced sulfhydryl compounds or ascorbate, the effect of CSH cannot be explained by action as a sulfhydryl protectant or heme reductant. Preincubation of enzyme extract with CSH, followed by rapid gel filtration, could not substitute for inclusion of CSH with heme during the reaction. The results suggest that CSH must specifically interact with the enzyme extract in the presence of the inhibitor to enhance the inhibition.

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“…Moreover, the reactivities of the monomeric and dimeric ferrihaem molecules in any given system may differ markedly. This differential reactivity has in fact been observed in all the aqueous ferrihacm reactions investigated in detail, including the degadation of ferrihaem to bile pigment (Jones et al, 1973a;Brown et al, 1974) and the use of ferri- Vol. 153 haem in catalase model systems (Brown etal., 1970b;Jones etal., 1973b).…”

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confidence: 85%

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

Brown

Shillcock

Jones

1976

Biochemical Journal

226

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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Haemoglobulin catabolism: the role of ferrihaems in studies of the degradation pathway (Short Communication)

Cited by 16 publications

References 11 publications

Cation Modulation of Hemoglobin Interaction with Sodium n-Dodecyl Sulfate (SDS). I: Calcium Modulation at pH 7.20

Cation Modulation of Hemoglobin Interaction with Sodium n-Dodecyl Sulfate (SDS). I: Calcium Modulation at pH 7.20

Heme Inhibition of [delta]-Aminolevulinic Acid Synthesis Is Enhanced by Glutathione in Cell-Free Extracts of Chlorella

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

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