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Showing papers on "Protoporphyrin IX published in 1985"


Journal ArticleDOI
TL;DR: Congo red binding was structurally specific; it was not influenced by a wide variety of compounds including amino acids and nucleotides and only weakly inhibited by structurally similar dyes, however, protoporphyrin IX and hemin were strong competitive inhibitors of Congo red binding.
Abstract: Congo red binding by virulent A-layer-containing (A+) and avirulent A-layer-deficient (A-) strains of Aeromonas salmonicida was examined. Congo red binding to A+ cells was enhanced by salt and thus hydrophobically driven, but at low Congo red concentrations binding was salt independent. Congo red was bound by A+ cells by a kinetically distinct mechanism (Kd, 0.25 microM) which was absent in A- isogenic strains. Purified A-layer protein ("A protein") protein A also bound Congo red with similar affinity (Kd, 0.40 microM). Congo red binding was structurally specific; it was not influenced by a wide variety of compounds including amino acids and nucleotides and only weakly inhibited by structurally similar dyes. However, protoporphyrin IX and hemin were strong competitive inhibitors of Congo red binding. Protoporphyrin and hemin were bound only by A+ strains (KdS of 0.41 and 0.63 microM, respectively). Furthermore, binding of these porphyrins was strongly inhibited by Congo red but weakly inhibited by hematoporphyrin. Purified A protein also bound protoporphyrin IX and hemin with affinities similar to those of A+ cells (KdS of 0.94 and 0.41 microM, respectively.

105 citations


Journal ArticleDOI
TL;DR: Reduction of binding following preincubation with trypsin, in conjunction with the above data, suggests that this cell type may display a receptor for heme which is comprised, as least in part, of protein.

70 citations


Journal ArticleDOI
TL;DR: F fluorometric assays for two enzymes of the heme pathway, coproporphyrinogen oxidase and protoporphyrins oxidase are described, based on measurement of protoprophyrin IX fluorescence generated from coproprophyr inogen III by the two consecutive reactions catalyzed by copropoiryrinogens oxidase & oxidase.

53 citations


Journal Article
TL;DR: Observed patterns of porphyrin accumulation produced in response to two DDC analogues that did not inhibit ferrochelatase are consistent with the inability of these analogues to inhibit fer rochelatases.
Abstract: The ferrochelatase-reducing activity and cytochrome P-450- and heme-destructive effects of a variety of analogues of 3,5-diethoxycarbonyl-1,4-dihydro-2,4,6-trimethylpyridine (DDC) were studied in chick embryo liver cells. A group of DDC analogues was found in which an inability to reduce ferrochelatase activity corresponded with an inability to cause cytochrome P-450 and heme destruction. In a second group of DDC analogues, the ability to reduce ferrochelatase activity corresponded with the ability to cause cytochrome P-450 and heme destruction. These observations support the idea that the protoporphyrin IX moiety of N-alkylprotoporphyrin IX originates from the heme moiety of cytochrome P-450. A third group of DDC analogues caused cytochrome P-450 and heme destruction despite an inability to reduce ferrochelatase activity. With this third group of DDC analogues, the heme moiety of cytochrome P-450 is likely degraded to products other than N-alkylporphyrins. The inability of several lipophilic DDC analogues [4-benzyl, 4-isopropyl, 4-cyclohexyl, 4-(3-cyclohexenyl)] to reduce hepatic ferrochelatase activity may explain their low porphyrinogenicity. The pattern of porphyrin accumulation produced in response to two DDC analogues that did not inhibit ferrochelatase was investigated using high performance liquid chromatography. Coproporphyrin was the major porphyrin to accumulate in response to the 4-isopropyl analogue and uro- and heptacarboxylic acid porphyrins in response to the 4-benzyl analogue. These patterns of porphyrin accumulation are consistent with the inability of these analogues to inhibit ferrochelatase.

28 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that if carbon monoxide is passed into a solution of protoporphyrin IX iron(III) containing pyridine and glutathione (in excess) for twenty minutes evidence for a characteristic absorption band at 445 nm like that typical for cytochrome P450 is confirmed.

14 citations


Journal ArticleDOI
TL;DR: Results indicate that one means whereby porphyrins accumulate in tissues is the occupation of intracellular binding sites, such as the transferases, as shown by the relative inhibitory effectiveness.
Abstract: Several naturally occurring porphyrins and porphyrins used in photodynamic therapy inhibit glutathione S-transferase isoenzymes either purified from rat liver or lung or in cytosol from normal and from cancerous (Morris 7288C hepatoma) liver. Although differences occur in the type and amount of transferases in normal and cancerous liver and in the liver of rats bearing an extrahepatic tumour, these enzymes are potential binding sites for porphyrins. Porphyrin structure is an important factor in determining the affinity of binding, as shown by the relative inhibitory effectiveness. Of the dicarboxylic porphyrins in the mixture used clinically, OO'-diacetylhaematoporphyrin and monohydroxyethylmonovinyldeuteroporphyrin are more effective inhibitors than haematoporphyrin and protoporphyrin IX. Of the naturally occurring porphyrins the order of effectiveness is protoporphyrin IX (dicarboxylic) greater than coproporphyrin (tetracarboxylic) greater than uroporphyrin (octacarboxylic) and type I greater than type III isomers of both uroporphyrin and coproporphyrin, and the synthetic tetra-meso-phenylporphinetetrasulphonate is a better inhibitor (apparent Ki = 250 nM) than coproporphyrin, which contains a comparable number of negative charges. In addition, iron-porphyrin chelates are more effective inhibitors of the transferases, with 25-fold decrease in Ki value, than the free porphyrins. These results indicate that one means whereby porphyrins accumulate in tissues is the occupation of intracellular binding sites, such as the transferases. Since porphyrins inhibit the activity of these important detoxifying enzymes, there will be metabolic consequences to the cell.

12 citations


Journal ArticleDOI
TL;DR: Mossbauer parameters of frozen solutions of protoporphyrin IX iron(II) (containing either 2-methyl-piperidine or mercaptoethanol as the fifth iron ligand) that were exposed to oxygen before freezing are similar to those of oxyhaemoglobin this article.

9 citations


Journal ArticleDOI
TL;DR: In this paper, the superoxide formation during the irradiation of FeIII protoporphyrin IX in oxygenated alkaline aqueous ethanol and the very short reoxidation time of the photoredox FeII porphrin product are consistent with a photoinduced electron transfer from ethanol to oxygen occurring with the assistance of an FeIII porphryin ethanolate complex.
Abstract: The evidence of superoxide formation during the irradiation of FeIII protoporphyrin IX in oxygenated alkaline aqueous ethanol and the very short re-oxidation time of the photoredox FeII porphyrin product are consistent with a photoinduced electron transfer from ethanol to oxygen occurring with the assistance of an FeIII porphyrin ethanolate complex.

7 citations


Journal ArticleDOI
TL;DR: Upon photoirradiation under aerobic conditions, the porphyrin prosthetic group in Mg-substituted horseradish peroxidase was oxidized to a mixture of its pi-cation radical and an oxidized product with an absorption band at 448 nm.

5 citations


Journal ArticleDOI
TL;DR: Gemas Formelschema werden ausgehend von Protoporphyrin-IX-dimethylester (I) die Benzoporphyrine (V) bzw. (XI) dargestellt as mentioned in this paper.
Abstract: Gemas Formelschema werden ausgehend von Protoporphyrin-IX-dimethylester (I) die Benzoporphyrine (V) bzw. (XI) dargestellt.

1 citations