607-14-7Relevant academic research and scientific papers
Photoinitiated Electron Transfer between Cytochrome c and Cytochrome c Oxidase Using a Novel Uroporphyrin/NADH Reducing System
Larsen, Randy W.,Winkler, Jay R.,Chan, Sunney I.
, p. 8023 - 8027 (1992)
We have employed a novel photoreduction system to investigate the electron-transfer reaction between cytochrome c and cytochrome c oxidase.In this system, the photogenerated uroporphyrin triplet state is quenched through electron transfer to ferricytochrome c.The corresponding uroporphyrin ?-cation radical is rapidly reduced by nicotonamid adenine dinucleotide (NADH) resulting in the in situ generation of ferrocytochrome c.In the presence of cytochrome c oxidase, cytochrome c is reoxidized biphasically while the corresponding reduction of cytochrome a appears to be monophasic.In addition, the fast-phase rate constants are dependent upon the concentration of cytochrome c oxidase giving a first-order intracomplex electron-transfer rate constant, (ket), of 1829 +/-248 s-1.The ratio of electron transferred from ferrocytochrome c to cytochrome a is 1:1 indicating that cytochrome a is the ultimate acceptor of the electrons.
Abiotic formation of uroporphyrinogen and coproporphyrinogen from acyclic reactants
Lindsey, Jonathan S.,Chandrashaker, Vanampally,Taniguchi, Masahiko,Ptaszek, Marcin
supporting information; scheme or table, p. 65 - 75 (2011/04/14)
Tetrapyrrole macrocycles (e.g., porphyrins) have long been proposed as key ingredients in the emergence of life, yet plausible routes for forming their essential pyrrole precursor have previously not been identified. Here, the anaerobic reaction of δ-aminolevulinic acid (ALA, 5-240 mM) with 5-methoxy-3-(methoxyacetyl)levulinic acid (1-AcOH, 5-240 mM) in water (pH 5-7) at 25-85°C for a few hours to a few days affords uroporphyrinogen, which upon chemical oxidation gives uroporphyrin in overall yield of up to 10%. The key intermediate is the α-methoxymethyl-substituted analogue of the pyrrole porphobilinogen (PBG). Reaction of ALA and the decarboxy analogue of 1-AcOH (1-Me) gave coproporphyrinogen (without its biosynthetic precursor uroporphyrinogen as an intermediate); oxidation gave the corresponding coproporphyrin in yields comparable to those for uroporphyrin. In each case a mixture of porphyrin isomers was obtained, consistent with reversible oligopyrromethane formation. The route investigated here differs from the universal extant biosynthetic pathway to tetrapyrrole macrocycles, where uroporphyrinogen (isomer III) - nature's last common precursor to corrins, heme, and chlorophylls - is derived from eight molecules of ALA (via four molecules of PBG). The demonstration of the spontaneous self-organization of eight acyclic molecules to form the porphyrinogen under simple conditions may open the door to the development of a chemical model for the prebiogenesis of tetrapyrrole macrocycles. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.
Direct assay of enzymes in heme biosynthesis for the detection of porphyrias by tandem mass spectrometry. Uroporphyrinogen decarboxylase and coproporphyrinogen III oxidase
Wang, Yuesong,Gatti, Paula,Sadilek, Martin,Scott, C. Ronald,Turecek, Frantisek,Gelb, Michael H.
, p. 2599 - 2605 (2008/09/20)
We report new assays of enzymes uroporphyrinogen decarboxylase (UROD) and coproporphyrinogen III oxidase (CPO) in the heme biosynthetic pathway. The assays were developed for use in clinical diagnostics of inherited disorders porphyria cutanea tarda and hereditary coproporphyria, respectively. Electrospray ionization tandem mass spectrometry is used to monitor the decarboxylation of pentaporphyrinogen I or uroporphyrinogen III catalyzed by UROD and to determine the enzyme activity in human erythrocytes by measuring the production of coproporphyrinogen I or III. The Km value for pentaporphyrinogen I was measured as 0.17 ± 0.03 μM. A mass spectrometric assay was also developed for the two-step decarboxylative oxidation of coproporphyrinogen III to protoporphyrinogen IX catalyzed by CPO in mitochondria from human lymphocytes (Km = 0.066 ± 0.009 μM). The assays show good reproducibility, use simple workup by liquid-liquid extraction of enzymatic products, and employ commercially available substrates and internal standards.
Direct assay of enzymes in heme biosynthesis for the detection of porphyrias by tandem mass spectrometry. Porphobilinogen deaminase
Wang, Yuesong,Scott, C. Ronald,Gelb, Michael H.,Turecek, Frantisek
, p. 2606 - 2611 (2008/09/20)
We report a new assay of human porphobilinogen deaminase (PBGD). Deficiency in this enzyme activity causes acute intermittent porphyria, the most common disorder of heme biosynthesis. The assay involves incubation of blood erythrocyte lysate with porphobilinogen, the natural PBGD substrate. Two subsequent enzymes in the heme biosynthetic pathway, uroporphyrinogen III synthase and uroporphyrinogen decarboxylase, are deactivated by heating so that their activity does not interfere with the PBGD assay. Electrospray ionization tandem mass spectrometry (ESI-MS/MS) is used to monitor the production of uroporphyrinogen I and thus measure the PGBD activity. A simple and efficient workup using liquid-liquid extraction with >90% product recovery was employed to avoid separation by liquid chromatography. The assays show good reproducibility (±3.3%) and linear dependence of the uroporphyrinogen I formation on incubation time and protein amount. The Km of PGBD for porphobilinogen was measured as 11.2 ± 0.5 μM with Vmax of 0.0041 ± 0.0002 μM/min·mg of hemoglobin). The coefficient of variation of PBGD activity among several unaffected individuals (12%) is significantly lower than the decrease due to acute intermittent porphyria (50%).
Studies on the formation of porphyrinogens from monopyrroles in presence of the enzymes PBG deaminase and/or Uro'gen III synthase
Pichon-Santander, Clotilde,Ian Scott
, p. 8669 - 8672 (2007/10/03)
The substrate-specificities of two enzymes in the biosynthetic pathway to vitamin B12, PBG deaminase and Uro'gen III synthase, which are involved in the formation of Uro'gen III from the pyrrole PBG, are investigated for the preparation of Uroporphyrin analogs. Both enzymes display strong substrate-specificity. However, tetramerization of pyrroles with carboxylate β-substituents in mildly basic buffer represents the best and most rapid route to a family of Uro I analogs for enzymatic activity studies.
Non-enzymic tetramisation of ethyl 3-(4-ethoxycarbonylmethyl-1H-pyrrol-3-yl)propionate with formaldehyde follows a similar course to the non-enzymic tetramisation of porphobilinogen
Cheung, Kwai-Ming,Shoolingin-Jordan, Peter M.
, p. 5973 - 5976 (2007/10/03)
The octaethyl esters of uroporphyrins were formed directly from ethyl 3-(4-ethoxy-carbonylmethyl-1H-pyrrol-3-yl)propionate and formalin in a yield of ca. 30% with the isomers I, II, III and IV being formed in the ratio 1:1:4:2. Under anaerobic conditions, the colourless uroporphyrinogen esters were formed in a similar ratio. These observations parallel the non-enzymic formation of uroporphyrinogens from the naturally occurring tetrapyrrole precursor, porphobilinogen, highlighting the similarity in both tetramisation and isomerisation reactions.
Protease mediated drug delivery system
-
, (2008/06/13)
Lipophilic and amphiphilic therapeutic or diagnostic agents having water solubilizing groups attached thereto by bonds that can be cleaved readily by one or more of the various proteases that are active in the extracellular fluid or on the surfaces of cells in many types of malignant tissue may accumulate selectively in such malignant tissues. Protease mediated removal of the water solubilizing groups converts such drugs into lipophilic or amphiphilic forms which are more soluble in plasma membrane lipids and which therefore enter cells more readily. Since the extracellular fluid in most non-malignant tissues under normal circumstances has little such protease activity, removal of the water solubilizing groups takes place primarily within malignant tissues, with consequent preferential accumulation of the lipophilic or amphiphilic forms of the drug within malignant tissues. Certain lipophilic and amphiphilic porphyrins and chlorins may be modified by the addition of water solubilizing groups, such as alcohols, which are attached by short polypeptide chains, that are stable while in the circulation but are cleaved by proteases in malignant tissue to provide novel compounds useful for the photodynamic therapy of cancer.
Biosynthesis of corrinoids and porphyrinoids. VII. Uroporphyrins from Saccharopolyspora erythraea
Kajiwara,Hara,Mizutani,Kondo
, p. 3321 - 3323 (2007/10/02)
Cultured broth of Saccharopolyspora erythraea shows a strong red fluorescence. The main fluorescent component was identified as uroporphyrin I by FAB-MS and 1H-NMR. This was confirmed by a feeding experiment using [5-13C]aminolevulinic acid.
Driving force dependence of rate constant of electron transfer within cytochrome c uroporphyrin complexes
Zhou, Jian S.,Rodgers, Michael A. J.
, p. 7728 - 7734 (2007/10/02)
Long-range electron-transfer reactions within preformed electrostatically associated complexes between metallocytochrome c (Mn(III)cytc and Zncytc) and metallouroporphyrins (Up, ZnUp, Mn(III)Up, and Fe(III)Up(CN)2) have been studied by time-resolved absorption spectroscopy. Rate constants for photoinduced forward and thermal backward electron-transfer reactions are as follows: 8.2 × 105 s-1 (3ZnUp*/Mn(III)cytc); 9.1 × 105 s-1 (3Up*/Mn(III)cytc); 1.5 × 104 s-1 (3Zncytc*/Mn(III)Up); 2.1 × 105 s-1 (3ZnUp*/Mn(III)cytc); 1.9 × 106 s-1 (Up.+/Mn(II)cytc); 5.5 × 104 s-1 (Zncytc.+/Mn(II)Up); 9.1 × 104 s-1 (3Zncytc*/Fe(III)Up(CN)2); and 6.0 × 103 s-1 (Zncyte.+/Fe(II)Up(CN)2), These data, together with those reported previously from this laboratory, provide seven unimolecular electron-transfer reactions for each type of reaction spanning an 0.8-V driving force range. The variation of rate constants with driving force for the thermal reactions confirms the predictions of semiclassical theory of the electron-transfer reaction; i.e., a maximum rate constant and an inverted region are clearly observed. Fitting the data yields a reorganization energy (λ) of 0.70 eV. However, no inverted region was observed for the photoinduced electron-transfer reactions over the same range of driving force (0.30-1.29 V). The lack of the inverted region for photoinduced electron-transfer reactions is possibly explained by a contribution of the coordinate solvent mode to the total outer-sphere reorganization energy or by a two-step mechanism.
UV-Visible and Carbon NMR Studies of Chloroquine Binding to Urohemin I Chloride and Uroporphyrin I in Aqueous Solutions
Constantinidis, I.,Satterlee, James D.
, p. 4391 - 4395 (2007/10/02)
Interactions of the antimalaria drug chloroquine with urohemin I and uroporphyrin I have been studied in aqueous solutions at pH 6.0 and 22 +/- 1 deg C with UV-visible and natural abundance carbon NMR spectroscopies.Both tetrapyrroles are water soluble and were chosen because their aggregation properties are understood and can be regulated by concentration and ionic strength.Chloroquine binding to urohemin I monomer has a stoichiometry of two urohemin molecules to one chloroquine molecule with an apparent association equilibrium constant of (7.8 +/- 0.4) * 108 M-2 at pH 6.0 and a urohemin concentration of 10-6 M.This stoichiometry is identical with that recently reported for complexes of urohemin I with another antimalarial, quinine.In that case, the binding was found to be cooperative, whereas in this case drug binding is noncooperative.Uroporphyrin binds to chloroquine with 1:1 stoichiometry and an apparent equilibrium constant of (2.8 +/- 0.2) * 106 M-1 at a uroporphyrin concentration 10-6 M.Carbon NMR spectroscopy and optical methods best describe these complexes as cofacial ? - ? dimers with structures different from the quinine complexes of the same tetrapyrroles.
