- Biosynthesis of corrinoids and porphyrinoids. XI. Source of oxaloacetic acid for uroporphyrinogen III biosynthesis in Arthrobacter hyalinus
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The source of oxaloacetic acid, required for the synthesis of porphyrins in Arthrobacter hyalinus, was examined by means of a feeding experiment with [1,3-13C2]glycerol, which is transformed to pyruvic acid. A half of the carbon dioxide liberated from pyruvic acid in the formation of acetyl CoA was utilized for carboxylation of pyruvic acid to generate oxaloacetic acid.
- Iida, Katsumi,Aoki, Toshiko,Uegaki, Ryuichi,Kajiwara, Masahiro
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- Crystal structure of the heme d1 biosynthesis enzyme NirE in complex with its substrate reveals new insights into the catalytic mechanism of S-adenosyl-L-methionine-dependent uroporphyrinogen III methyltransferases
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During the biosynthesis of heme d1, the essential cofactor of cytochrome cd1 nitrite reductase, the NirE protein catalyzes the methylation of uroporphyrinogen III to precorrin-2 using S-adenosyl-L-methionine (SAM) as the methyl group donor. The crystal structure of Pseudomonas aeruginosa NirE in complex with its substrate uroporphyrinogen III and the reaction by-product S-adenosyl-L-homocysteine (SAH) was solved to 2.0 A resolution. This represents the first enzyme-substrate complex structure for a SAM-dependent uroporphyrinogen III methyltransferase. The large substrate binds on top of the SAH in a puckered conformation in which the two pyrrole rings facing each other point into the same direction either upward or downward. Three arginine residues, a histidine, and a methionine are involved in the coordination of uroporphyrinogen III. Through site-directed mutagenesis of the nirE gene and biochemical characterization of the corresponding NirE variants the amino acid residues Arg-111, Glu-114, and Arg-149 were identified to be involved in NirE catalysis. Based on our structural and biochemical findings, we propose a potential catalytic mechanism for NirE in which the methyl transfer reaction is initiated by an arginine catalyzed proton abstraction from the C-20 position of the substrate.
- Storbeck, Sonja,Saha, Sayantan,Krausze, Joern,Klink, Bjoern U.,Heinz, Dirk W.,Layer, Gunhild
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- Irgasan DP 300 (5-chloro-2-(2,4-dichlorophenoxy)-phenol) induces cytochrome P450s and inhibits haem biosynthesis in rat hepatocytes cultured on Matrigel.
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1. The effect of Irgasan DP 300 (5-chloro-2-(2,4-dichlorophenoxy)phenol) on cytochrome P450 (P450) induction and haem biosynthesis was studied in rat hepatocytes cultured on Matrigel. 2. Irgasan DP 300 significantly induced 7-benzyloxyresorufin O-debenzylase activity, followed by 7-pentoxyresorufin O-depentylase and 7-ethoxyresorufin O-deethylase activities. 4-Nitrophenol hydroxylase, testosterone 6 beta-hydroxylase and methoxyresorufin O-demethylase activities were also slightly increased. The maximum induction of these enzyme activities was obtained at the same concentration of 125 microM in the culture medium. 3. Immunochemical blots using anti-rat cytochrome P450 antibodies revealed that Irgasan DP 300 preferably induced CYP2B1/2 along with a slight increase in 3A. These results indicate that Irgasan DP 300 is a phenobarbital-type inducer. 4. In the absence of exogenous 5-aminolevulinic acid (ALA), slight increases in protoporphyrin IX (2.6-fold) and coproporphyrin III (1.3-fold) were observed in the Irgasan DP 300-treated cultures. In contrast, when 75 microM ALA was present, Irgasan DP 300 (250 microM) caused an extensive accumulation of uroporphyrin I (13-fold). 5. Irgasan DP 300 inhibited rat hepatic uroporphyrinogen III synthase in vitro. 6. These results indicate that Irgasan DP 300 produced accumulation of hydroxymethylbilane in rat hepatocytes by inhibiting uroporphyrinogen III synthase, and consequently an accumulation of uroporphyrin I.
- Jinno,Hanioka,Onodera,Nishimura,Ando
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- Handling heme: The mechanisms underlying the movement of heme within and between cells
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Heme is an essential cofactor and signaling molecule required for virtually all aerobic life. However, excess heme is cytotoxic. Therefore, heme must be safely transported and trafficked from the site of synthesis in the mitochondria or uptake at the cell surface, to hemoproteins in most subcellular compartments. While heme synthesis and degradation are relatively well characterized, little is known about how heme is trafficked and transported throughout the cell. Herein, we review eukaryotic heme transport, trafficking, and mobilization, with a focus on factors that regulate bioavailable heme. We also highlight the role of gasotransmitters and small molecules in heme mobilization and bioavailability, and heme trafficking at the host-pathogen interface.
- Donegan, Rebecca K.,Moore, Courtney M.,Hanna, David A.,Reddi, Amit R.
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- Synthesis of substrate analogs of methyltransferases in the vitamin B12 biosynthetic pathway and characterization of their enzymatic products
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The specificity toward substrate analogs of the first two methyltransferases in the vitamin B12 biosynthetic pathway was probed with 15 synthetic porphyrinogens. Several novel methylated chlorins and isobacteriochlorins were isolated and charac
- Pichon-Santander, Clotilde,Santander, Patricio J.,Scott, A. Ian
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p. 3904 - 3922
(2007/10/03)
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- BIOSYNTHESIS OF PORPHYRINS AND RELATED MACROCYCLES. PART 27. SYNTHESES OF MODIFIED HYDROXYMETHYLBILANES AND STUDIES OF THEIR CHEMICAL AND BIOLOGICAL PROPERTIES.
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The biosynthetic pathway to uroporphyrinogen-III, the parent macrocycle for all the pigments of life, involves the formation and ring-closure of an hydroxymethylbilane.The non-enzymic ring-closure of this bilane is studied under different pH conditions.Also octamethyl esters of related bilanes are synthesised which have either a cyano or a methyl group blocking position-19 which is free on the terminal ring-D of the natural bilane.Studies are made of the ring-closure of these substituted bilanes under acidic conditions.The conclusion is reached that there is a strong preference for non-enzymic ring-closure of an hydroxymethylbilane to occur at the terminal carbon atom (position-19).The octa-acids derived from the cyano and methyl substituted bilanes inhibit the action of cosynthetase on the natural hydroxymethylbilane.
- Anderson, Paul C.,Battersby, Alan R.,Broadbent, Hugo A.,Fookes, Christopher J. R.,Hart, Graham J.
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p. 3123 - 3136
(2007/10/02)
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- Biosynthesis of Porphyrins and Related Macrocycles. Part 17. Chemical and Enzymic Transformation of Isomeric Aminomethylbilanes into Uroporphyrinogens: Proof that Unrearranged Bilane is the Preferred Enzymic Substrate and Detection of a Transient Intermed
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Six isomeric aminomethylbilanes have been built by unambiguous synthesis.One bilane has the unrearranged structure corresponding to straightforward head-to-tail assembly of four units of porphobilinogen; the other five bilanes have one or more of the pyrr
- Battersby, Alan R.,Fookes, Christopher J. R.,Gustafson-Potter, Kerstin E.,McDonald, Edward,Matcham, George W. J.
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p. 2413 - 2426
(2007/10/02)
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- Biosynthesis of Porphyrins and Related Macrocycles. Part 18. Proof by Spectroscopy and Synthesis that Unrearranged Hydroxymethylbilane is the Product from Deaminase and the Substrate for Cosynthetase in the Biosynthesis of Uropophyrinogen-III
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When the enzyme deaminase acts alone on porphobilinogen, it releases a tarnsient intermediate into the medium which is unaffected by further treatment with a large excess of deaminase.The intermediate undergoes rapid ring-closure chemically (t1/2/su
- Battersby, Alan R.,Fookes, Christopher J. R.,Gustafson-Potter, Kerstin E.,McDonald, Edward,Matcham, George W. J.
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p. 2427 - 2444
(2007/10/02)
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- Synthesis of Bilanes of Biosynthetic Interest
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A series of bilanes of biosynthetic interest and formally derived from porphobilinogen were prepared by reduction of the corresponding b-bilenes.The latter were prepared by condensation of a -5-formyldipyrryl>methane with dipy
- Diaz, Luis,Valasinas, Aldonia,Frydman, Benjamin
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p. 864 - 867
(2007/10/02)
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- Biosynthesis of Porphyrins and Related Macrocycles. Part 15. Chemical and Enzymic Formation of Uroporphyrinogen Isomers from Unrearranged Aminomethylpyrromethane: Separation of Isomeric Coproporphyrin Esters
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The unrearranged pyrromethane (1) is transformed chemically mainly into uro'gen-I with a smaller amount of uro'gen-IV but only traces of uro'gen-III are formed.Uro'gen-I is produced via a tetrapyrrolic (bilane) intermediate and when the diaminase-cosynthetase enzyme system from Euglena gracilis is present, this intermediate is converted into uro'gen-III.The rearrangement step for this conversion has the same characteristics found earlier for the natural biosynthetic process from porphobilinogen.Pyrromethane (1) is not a direct biosynthetic precursor of uro'gen-III and reasons are advanced why this is understandable.Methods are developed based on high pressure liquid chromatography for the separation of all four isomeric coproporphyrin esters.
- Battersby, Alan R.,Buckley, Dennis G.,Johnson, Dawid W.,Mander, Lewis N.,McDonald, Edward,Williams, D. Clive
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p. 2779 - 2785
(2007/10/02)
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- Biosynthesis of Porphyrins and Related Macrocycles. Part 16. Proof that the Single Intramolecular Rearrangement leading to Natural Porphyrins (Type-III) occurs at the Tetrapyrrole Level
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The unrearranged aminomethylbilane (2) is synthesised by a rational route and is proved to be converted by the enzymes deaminase and cosynthetase, working co-operatively, into uro'gen-III (3).The single rearrangement step established earlier is thus proved to take place at the tetrapyrrole level.Synthesis of singly 13C-labelled bilane (2) followed by its enzymic conversion into uro'gen-III serves to register each of the pyrrole rings of the product relative to the initial bilane.Finally, methods for synthesis of the bilane are developed in two different doubly 13C-labelled forms to allow the following key points to be established largely by 13C n.m.r. spectroscopy: (a) as the bilane system is converted into uro'gen-III, intramolecular rearrangement of the terminal ring D occurs, and (b) the linear tetrapyrrole is converted intact into uro'gen-III.Syntheses of -, and -uroporphyrin octamethyl ester are described together with improved h.p.l.c. conditions for the separation of isomeric coproporphyrin tetramethyl esters.
- Battersby, Alan R.,Fookes, Christopher J. R.,Meegan, Mary J.,McDonald, Edward,Wurziger, Hanns K. W.
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p. 2786 - 2799
(2007/10/02)
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- The carbon-13 and nitrogen-15 nuclear magnetic resonance spectra of uroporphyrinogens I and III
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Due to their sensitivity to light and air, porphyrinogens are not normally isolated, but are routinely analyzed by oxidation to the corresponding porphyrin. We report herein the 13C- and 15N-NMR spectra of uroporphyrinogens I and III in their "native state", multiply labelled with 13C and 15N, and at natural abundance (13C only).
- Burton, Gerardo,Fagerness, Paul E.,Jordan, Peter M.,Scott
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p. 2721 - 2725
(2007/10/02)
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