Showing papers on "Protoporphyrin IX published in 1983"
Journal Article•
TL;DR: These data provide a potential mechanism of action, i.e., inhibition of respiration, for porphyrin-induced photosensitivity, and they offer a useful assay to investigate this family of therapeutic agents.
Abstract: Mitochondrial cytochrome c oxidase activity was inhibited by exposure to hematoporphyrin derivative followed by photoirradiation. Inhibition of enzyme activity in vitro was a dose- and time-related event, the log of percentage inhibition being linear with time. Exposure of mitochondria to hematoporphyrin or hydroxyethylvinyldeuteroporphyrin sensitized mitochondria to photoirradiation, whereas protoporphyrin IX was only weakly active as a photosensitizer for inhibition of cytochrome c oxidase. Mitochondria from mammary glands of pregnant rats showed hematoporphyrin-induced photosensitivity similar to those from R3230AC mammary adenocarcinomas. Mitochondria prepared from tumors of animals given injections of hematoporphyrin derivative in vivo and then photoirradiated in vitro demonstrated considerable sensitivity to light as reflected by significant inhibition of cytochrome c oxidase activity. A side by side comparison of hematoporphyrin derivative with hematoporphyrin, using this in vivo-in vitro experimental protocol, indicated that photosensitivity was retained for a longer time after treatment with hematoporphyrin derivative. Taken together, these data provide a potential mechanism of action, i.e., inhibition of respiration, for porphyrin-induced photosensitivity, and they offer a useful assay to investigate this family of therapeutic agents.
131 citations
TL;DR: Mossbauer spectroscopic studies on frozen solutions of protoporphyrin IX iron(II) in the pH range 7-14 reveal evidence for three different species.
96 citations
TL;DR: The direction of this effect, fluorescence quenching, suggests that these salts promote an increase in aggregation, and the magnitudes of the effect, among different salt species sharing a common anion, at constant ionic strength, imply that the effect is cation-specific.
Abstract: The aggregations of protoporphyrin IX and haematoporphyrin IX in aqueous solutions were studied by fluorimetric techniques. Porphyrin concentrations were limited to 0.001-0.1 microM and 0.01-1 microM for protoporphyrin and haematoporphyrin respectively, where dimerization is the dominant aggregation process. The dimerization equilibrium constants (at 25 degrees C, neutral pH, 50 mM-Tris/HCl buffer) were determined to be 3 X 10(7) M and 4 X 10(5) M for the proto and the haemato derivatives respectively. The fluorescence intensity of a given protoporphyrin solution (within the range indicated above) was markedly decreased by salts in the system, over the salt concentration range 0.1-7 mM at constant ionic strength, in the sequence CaCl2 greater than MgCl2 greater than KCl greater than NaCl. The direction of this effect, fluorescence quenching, suggests that these salts promote an increase in aggregation. The differences in the magnitudes of the effect, among different salt species sharing a common anion, at constant ionic strength, imply that the effect is cation-specific. In contrast, the fluorescence intensity of a given solution of haematoporphyrin (within the range indicated above) was unaffected by these salts, under similar concentrations, nor was it sensitive to the total buffer concentration, or to the type of buffer in the system.
95 citations
59 citations
TL;DR: The ability of NMMP to cause intracellular accumulation of protoporphyrin and to block PC synthesis specifically while allowing normal Chl formation is consistent with its action as a specific inhibitor of enzymic iron chelation, and supports the role of heme as a precursor to the phycobilins.
Abstract: The ability of N -methyl mesoporphyrin IX (NMMP) to block heme synthesis by specifically inhibiting enzymic iron insertion into protoporphyrin IX was exploited to test whether heme is a precursor of the bilin chromophore of phycocyanin (PC). A strain of the unicellular rhodophyte Cyanidium caldarium which forms normal amounts of both chlorophyll (Chl) and PC in the dark was employed to avoid phototoxic effects of exogenous porphyrins. Relative Chl and PC content were assayed spectrophotometrically on whole cell suspensions. When cells were grown in the dark on a glucose-based heterotrophic medium at 42°C, neither division rate nor Chl synthesis was affected by NMMP up to 3.0 micromolar and for as long as 72 hours. NMMP had a dose-dependent inhibitory effect on PC synthesis. PC to Chl absorbance ratios, relative to control cell values, were 100%, 89%, 86%, and 50% in cells grown for 48 hours with 0.3, 1.0, 3.0, and 10.0 micromolar NMMP, respectively. NMMP also caused the accumulation of intracellular protoporphyrin. The ability of NMMP to cause intracellular accumulation of protoporphyrin and to block PC synthesis specifically while allowing normal Chl formation is consistent with its action as a specific inhibitor of enzymic iron chelation, and supports the role of heme as a precursor to the phycobilins.
41 citations
TL;DR: It appears that this enzyme purified from rat liver lacks haem (and perhaps other components) required for activation by NO, and it should be particularly useful for elucidating the mechanism of action of NO, protoporphyrin IX and other activators.
Abstract: Guanylate cyclase was purified from rat liver supernatant. Electrophoresis under denaturing conditions revealed one major peptide of Mr approx. 69 000. On the basis of the Stokes radius (4.7 nm) and S20,w (6.4S), the calculated Mr value of the native enzyme was 133 000, i.e. it is apparently a homodimer. Kinetics of inactivation by diamide (which was reversible with dithiothreitol) suggested that oxidation of a single class of thiol sites was involved. In the absence of other additions, cyclase activity assayed with Mn2+ was over 7 times that assayed with Mg2+; maximal effects were observed with approx. 5 mM of each (with 1 mM-GTP). The purified enzyme was markedly activated by nitrosylhaemoglobin. Relative activation was much greater in assays with Mg2+ than with Mn2+, although maximal activities were similar. When assayed with Mg2+, the enzyme exhibited a single Km (0.35 mM) for GTP; with Mn2+, plots of 1/v versus 1/[S] were non-linear. Activator or nitrosylhaemoglobin increased Vmax, but did not alter Km in the presence of either Mg2+ or Mn2+. The enzyme was inhibited by Na3VO4, Na2WO4 and Na2B4O7. Reduction from VV to VIV abolished the inhibitory effect of vanadate. Na2B4O7 (2 mM) inhibited activity with Mn2+, but not with Mg2+. In assays with Mg2+, but not with Mn2+, FMN, NAD+ and NADH (each 0.5 mM) inhibited activation by protoporphyrin IX and nitrosylhaemoglobin. Rotenone (0.6 mM) inhibited activity with protoporphyrin IX to a greater extent than with nitrosylhaemoglobin. Methylene Blue (1 mM) inhibited activation by nitrosylhaemoglobin, protoporphyrin IX and activator. It appears that this enzyme purified from rat liver lacks haem (and perhaps other components) required for activation by NO, and it should be particularly useful for elucidating the mechanism of action of NO, protoporphyrin IX and other activators.
19 citations
TL;DR: Results indicate that heme synthesis is required for erythropoietin‐mediated induction of globin synthesis in cultured bone marrow cells.
Abstract: The effects of 4,6-dioxoheptanoic acid (succinylacetone, SA), an inhibitor of delta-aminolevulinic acid dehydratase, on total iron uptake, heme synthesis, and globin synthesis were studied in rat marrow cells in culture in order to examine the coordination of heme and globin synthesis. SA inhibited heme synthesis in both control and erythropoietin-stimulated cells in a dose-dependent fashion; at 10(-3) M, inhibition was complete, whereas at 10(-7) M, there was no significant effect. Inhibition of total iron uptake was also dose-dependent although, at 10(-3) M, it was not complete. The inhibition of heme synthesis by SA was partially overcome by addition of 10(-4) M porphobilinogen or protoporphyrin IX. SA caused an almost complete suppression of globin formation in both erythropoietin-stimulated and unstimulated cells as early as five hours after the addition of the inhibitor. When inhibition of heme synthesis was incomplete, globin synthesis was partially inhibited. These results indicate that heme synthesis is required for erythropoietin-mediated induction of globin synthesis in cultured bone marrow cells.
18 citations
TL;DR: In this paper, the interactions of monomer forms of coproporphyrin with cyclodextrin in 0.002 mol·dm−3 NaOH aqueous solution are indicated by change of electronic spectrum and induction of circular dichroism.
Abstract: Interactions of monomer forms of protoporphyrin IX, deuteroporphyrin IX, hematoporphyrin IX, and coproporphyrin III, respectively, with α- and γ-cyclodextrin in 0.002 mol·dm−3 NaOH aqueous solution are indicated by change of electronic spectrum and induction of circular dichroism. Dimerization constant of porphyrin and complex formation constant of porphyrin with cyclodextrin are also determined from the electronic spectra.
18 citations
TL;DR: The reaction of protoporphyrin IX, the mono- and diformyl oxidation products, and the “green” hydroxyaldehydes formed from protoporalin IX are discussed and preliminary results of quenching and sensitization studies in the organized media are discussed.
Abstract: We have studied the photooxidation of protoporphyrin IX and the related intermediates and products of its oxidation in homogeneous solution (mostly organic solvents) and in aqueous surfactant media, in particular, various micellar and vesicular media. Our contribution first discusses the reaction of protoporphyrin IX, the mono- and diformyl oxidation products, and the “green” hydroxyaldehydes formed from protoporphyrin IX. In solution, all of these compounds are good sensitizers for singlet oxygen; a small amount of the interaction of porphyrin excited states with molecular oxygen may result in electron transfer to give oxidized porphyrin (cation radicals) and superoxide anion. However, in most cases the singlet oxygen path is predominant. We have also measured the reactivity of the various porphyrin ground states with singlet oxygen. Our studies in organized assemblies show that reactivity may be quite different; studies still in progress are attempting to elucidate whether singlet oxygen remains the primary reactant in these processes. Preliminary results of quenching and sensitization studies in the organized media are discussed.
12 citations
TL;DR: It was concluded that N-hydroxyethylprotoporphyrin IX is the primary reaction product between an active metabolite of diethylnitrosamine and hepatic haem.
Abstract: The administration of di[1-14C]ethylnitrosamine to phenobarbital-pretreated mice resulted in the formation of a radiolabelled green pigment in their livers. Green-pigment concentrations were time- and dose-dependent, maximum levels being reached 1-2 h after dosing. There was only a slight decrease in cytochrome P-450 levels and accumulation of porphyrins in the liver at this time. Dimethyl- or dipropyl-nitrosamine also caused an accumulation of similar, though not identical, compounds in the liver. The formation of green pigment was induced by pretreatment of mice with phenobarbital or 3-methylcholanthrene and was inhibited by the acute administration of pyrazole or ethanol. From the absorption spectra, the green pigment methyl esters appeared to be N-alkylporphyrins. Analysis of the diethylnitrosamine-induced green pigment by high-pressure liquid chromatography showed it to be more polar than the expected N-ethylprotoporphyrin IX, having a retention time similar to that of N-hydroxyethylprotoporphyrin IX. Desorption chemical-ionization mass spectrometry gave a protonated molecular ion, m/z 635, compatible with N-hydroxyethylprotoporphyrin IX. The presence of a free hydroxy group was demonstrated by acetylation with [1-14C]acetic anhydride. No conversion of N-ethylprotoporphyrin IX into N-hydroxyethylprotoporphyrin IX could be demonstrated in vivo or in vitro. Little or no N-ethylprotoporphyrin IX accumulated in the livers of mice given diethylnitrosamine. It was concluded that N-hydroxyethylprotoporphyrin IX is the primary reaction product between an active metabolite of diethylnitrosamine and hepatic haem.
12 citations
TL;DR: The kinetics of the reaction of hydrated electron with ferric, ferrous, metal-free protoporphyrin IX-and apo-myoglobin have been studied by pulse radiolysis so that a direct kinetic measure of the relative reactivities of the heme and the protein part of myoglobin can be made.
TL;DR: In this paper, magnetic resonance and phosphorescence decay measurements for protoporphyrin IX in n -ocatane at 5 K were carried out, and the results were interpreted taking into account spin-orbit and vibronic coupling terms.
TL;DR: Data indicate that, in the presence of Mg2+, a heme-like structure can interact with the membrane-bound guanylate cyclase and regulate its activity.
TL;DR: The dose response, time course, enzyme subcellular distribution and chelation antagonism studies all suggest that heme itself, and not iron, regulates the rate limiting enzymatic steps of rat hepatic heme synthesis and degradation.
Patent•
20 Jan 1983
TL;DR: In this paper, an enzyme system consisting of NADP, D-glucose-6-phosphoric acid, glucose-6phosphor acid dehydrogenase, ferredoxin, and Ferredoxin-NADP reductase is made to reduce the iron to divalent state in the titled porphyrin complex.
Abstract: PURPOSE:An enzyme system consisting of NADP, D-glucose-6-phosphoric acid, glucose-6-phosphoric acid dehydrogenase, ferredoxin, and ferredoxin-NADP reductase is made to act to reduce the iron to divalent state in the titled complex CONSTITUTION:In an aqueous medium such as water or a phosphate buffer solution, a reducing agent is made to act on an iron (III) porphyrin complex such as protoporphyrin IX, duteroprophyrin IX, mesoporphyrin IX or hematoporphyrin IX This reducing agent is composed of an enzyme system containing NADP, D-glucose-6-phosphoric acid, glucose-6-phosphoric acid dehydrogenase, ferredoxin and ferredoxin-NADP reductase and may contain catalase additionally The amount of D-glucose-6-phosphoric acid is more than 1mol per mol of the iron (III) porphyrin complex and the aqueous medium is adjusted to 5-9 in pH
TL;DR: The sensitivity of human erythrocytes to photohemolysis sensitized by addition of protoporphyrin IX can be selectively affected by their enrichment with substances carried by cationic liposomes by enrichment with small amounts of β-carotene.
Abstract: The sensitivity of human erythrocytes to photohemolysis sensitized by addition of protoporphyrin IX can be selectively affected by their enrichment with substances carried by cationic liposomes. In particular the enrichment wich superoxide dismutase is accompanied by a copper-related greater sensitivity toward photohemolysis, as observed in the Down's syndrome (mongolism). Instead it is possible to protect the erythrocytes against the phototoxic effect of protoporphyrin by enrichment with small amounts of β-carotene.
TL;DR: This report investigated the responsiveness of mouse liver GC to MNNG or porphyrins and found that guanylate cyclase from various tissues is stimulated by nitric oxide, nitroso compounds and protoporphyrin IX(PTP IX).