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Liberato A, Aguinaco A, Clares MP, Delgado-Pinar E, Pitarch-Jarque J, Blasco S, Basallote MG, García-España E, Verdejo B. Pb2+ complexes of small-cavity azamacrocyclic ligands: thermodynamic and kinetic studies. Dalton Trans 2017; 46:6645-6653. [DOI: 10.1039/c7dt00680b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis and Pb2+ coordination of azamacrocyclic ligands have been described. This paper includes one of the few kinetic studies so far reported on the acid-promoted dissociation of Pb2+ macrocyclic complexes.
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Affiliation(s)
- A. Liberato
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica
- Facultad de Ciencias
- Universidad de Cádiz
- Puerto Real
- Spain
| | - A. Aguinaco
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica
- Facultad de Ciencias
- Universidad de Cádiz
- Puerto Real
- Spain
| | - M. P. Clares
- Instituto de Ciencia Molecular
- Departamento de Química Inorgánica
- Universidad de Valencia
- Edificio de Institutos de Paterna
- Paterna
| | - E. Delgado-Pinar
- Instituto de Ciencia Molecular
- Departamento de Química Inorgánica
- Universidad de Valencia
- Edificio de Institutos de Paterna
- Paterna
| | - J. Pitarch-Jarque
- Instituto de Ciencia Molecular
- Departamento de Química Inorgánica
- Universidad de Valencia
- Edificio de Institutos de Paterna
- Paterna
| | - S. Blasco
- Instituto de Ciencia Molecular
- Departamento de Química Inorgánica
- Universidad de Valencia
- Edificio de Institutos de Paterna
- Paterna
| | - M. G. Basallote
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica
- Facultad de Ciencias
- Universidad de Cádiz
- Puerto Real
- Spain
| | - E. García-España
- Instituto de Ciencia Molecular
- Departamento de Química Inorgánica
- Universidad de Valencia
- Edificio de Institutos de Paterna
- Paterna
| | - B. Verdejo
- Instituto de Ciencia Molecular
- Departamento de Química Inorgánica
- Universidad de Valencia
- Edificio de Institutos de Paterna
- Paterna
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Choy CJ, Fulton MD, Davis AL, Hopkins M, Choi JK, Anderson MO, Berkman CE. Rationally Designed Sulfamides as Glutamate Carboxypeptidase II Inhibitors. Chem Biol Drug Des 2013; 82:612-9. [DOI: 10.1111/cbdd.12174] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 05/07/2013] [Accepted: 05/28/2013] [Indexed: 11/29/2022]
Affiliation(s)
- Cindy J. Choy
- Department of Chemistry; Washington State University; Pullman; WA; 99164-4630; USA
| | - Melody D. Fulton
- Department of Chemistry; Washington State University; Pullman; WA; 99164-4630; USA
| | - Austen L. Davis
- Department of Chemistry; Washington State University; Pullman; WA; 99164-4630; USA
| | - Mark Hopkins
- Department of Chemistry; Washington State University; Pullman; WA; 99164-4630; USA
| | - Joseph K. Choi
- Department of Chemistry; Washington State University; Pullman; WA; 99164-4630; USA
| | - Marc O. Anderson
- Department of Chemistry and Biochemistry; San Francisco State University; San Francisco; CA; 94132; USA
| | - Clifford E. Berkman
- Department of Chemistry; Washington State University; Pullman; WA; 99164-4630; USA
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Abstract
This review is concerned specifically with the structures and biosynthesis of hemes in E. coli and serovar Typhimurium. However, inasmuch as all tetrapyrroles share a common biosynthetic pathway, much of the material covered here is applicable to tetrapyrrole biosynthesis in other organisms. Conversely, much of the available information about tetrapyrrole biosynthesis has been gained from studies of other organisms, such as plants, algae, cyanobacteria, and anoxygenic phototrophs, which synthesize large quantities of these compounds. This information is applicable to E. coli and serovar Typhimurium. Hemes play important roles as enzyme prosthetic groups in mineral nutrition, redox metabolism, and gas-and redox-modulated signal transduction. The biosynthetic steps from the earliest universal precursor, 5-aminolevulinic acid (ALA), to protoporphyrin IX-based hemes constitute the major, common portion of the pathway, and other steps leading to specific groups of products can be considered branches off the main axis. Porphobilinogen (PBG) synthase (PBGS; also known as ALA dehydratase) catalyzes the asymmetric condensation of two ALA molecules to form PBG, with the release of two molecules of H2O. Protoporphyrinogen IX oxidase (PPX) catalyzes the removal of six electrons from the tetrapyrrole macrocycle to form protoporphyrin IX in the last biosynthetic step that is common to hemes and chlorophylls. Several lines of evidence converge to support a regulatory model in which the cellular level of available or free protoheme controls the rate of heme synthesis at the level of the first step unique to heme synthesis, the formation of GSA by the action of GTR.
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4
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Puskar L, Barran PE, Duncombe BJ, Chapman D, Stace AJ. Gas-Phase Study of the Chemistry and Coordination of Lead(II) in the Presence of Oxygen-, Nitrogen-, Sulfur-, and Phosphorus-Donating Ligands. J Phys Chem A 2004; 109:273-82. [PMID: 16839117 DOI: 10.1021/jp047637f] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Using a pickup technique in association with high-energy electron impact ionization, complexes have been formed in the gas phase between Pb(2+) and a wide range of ligands. The coordinating atoms are oxygen, nitrogen, sulfur, and phosphorus, together with complexes consisting of benzene and argon in association with Pb(2+). Certain ligands are unable to stabilze the metal dication, the most obvious group being water and the lower alcohols, but CS(2) is also unable to form [Pb(CS(2))(N)](2+) complexes. Unlike many other metal dication complexes, those associated with lead appear to exhibit very little chemical reactivity following collisional activation. Such reactions are normally promoted via charge transfer and are initiated using the energy difference between M(2+) + e(-) --> M(+) and L --> L(+) + e(-), which is typically approximately 5 eV. In the case of Pb(2+), this energy difference usually leads to the appearance of L(+) and the loss of a significant fraction of the remaining ligands as neutral species. In many instances, Pb(+) appears as a charge-transfer product. The only group of ligands to consistently exhibit chemical reactivity are those containing sulfur, where a typical product might be PbS(+)(L)(M) or PbSCH(3)(+)(L)(M).
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Affiliation(s)
- Ljiljana Puskar
- Department of Chemistry, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom
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5
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Affiliation(s)
- Gerard Parkin
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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6
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7
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Jaffe EK, Volin M, Bronson-Mullins CR, Dunbrack RL, Kervinen J, Martins J, Quinlan JF, Sazinsky MH, Steinhouse EM, Yeung AT. An artificial gene for human porphobilinogen synthase allows comparison of an allelic variation implicated in susceptibility to lead poisoning. J Biol Chem 2000; 275:2619-26. [PMID: 10644722 DOI: 10.1074/jbc.275.4.2619] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Porphobilinogen synthase (PBGS) is an ancient enzyme essential to tetrapyrrole biosynthesis (e.g. heme, chlorophyll, and vitamin B(12)). Two common alleles encoding human PBGS, K59 and N59, have been correlated with differential susceptibility of humans to lead poisoning. However, a model for human PBGS based on homologous crystal structures shows the location of the allelic variation to be distant from the active site with its two Zn(II). Previous microbial expression systems for human PBGS have resulted in a poor yield. Here, an artificial gene encoding human PBGS was constructed by recursive polymerase chain reaction from synthetic oligonucleotides to rectify this problem. The artificial gene was made to resemble the highly expressed homologous Escherichia coli hemB gene and to remove rare codons that can confound heterologous protein expression in E. coli. We have expressed and purified recombinant human PBGS variants K59 and N59 in 100-mg quantities. Both human PBGS proteins purified with eight Zn(II)/octamer; Zn(II) binding was shown to be pH-dependent; and Pb(II) could displace some of the Zn(II). However, there was no differential displacement of Zn(II) by Pb(II) between K59 and N59, and simple Pb(II) inhibition studies revealed no allelic difference.
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Affiliation(s)
- E K Jaffe
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
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8
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Frankenberg N, Jahn D, Jaffe EK. Pseudomonas aeruginosa contains a novel type V porphobilinogen synthase with no required catalytic metal ions. Biochemistry 1999; 38:13976-82. [PMID: 10529244 DOI: 10.1021/bi9906470] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Porphobilinogen synthases (PBGS) are metalloenzymes that catalyze the first common step in tetrapyrrole biosynthesis. The PBGS enzymes have previously been categorized into four types (I-IV) by the number of Zn(2+) and/or Mg(2+) utilized at three different metal binding sites termed A, B, and C. In this study Pseudomonas aeruginosa PBGS is found to bind only four Mg(2+) per octamer as determined by atomic absorption spectroscopy, in the presence or absence of substrate/product. This is the lowest number of bound metal ions yet found for PBGS where other enzymes bind 8-16 divalent ions. These four Mg(2+) allosterically stimulate a metal ion independent catalytic activity, in a fashion dependent upon both pH and K(+). The allosteric Mg(2+) of PBGS is located in metal binding site C, which is outside the active site. No evidence is found for metal binding to the potential high-affinity active site metal binding sites A and/or B. P. aeruginosa PBGS was investigated using Mn(2+) as an EPR probe for Mg(2+), and the active site was investigated using [3,5-(13)C]porphobilinogen as an NMR probe. The magnetic resonance data exclude the direct involvement of Mg(2+) in substrate binding and product formation. The combined data suggest that P. aeruginosa PBGS represents a new type V enzyme. Type V PBGS has the remarkable ability to synthesize porphobilinogen in a metal ion independent fashion. The total metal ion stoichiometry of only 4 per octamer suggests half-sites reactivity.
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Affiliation(s)
- N Frankenberg
- Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Albertstrasse 21, 79104 Freiburg im Breisgau, Germany
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9
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D'Ordine RL, Klem TJ, Davisson VJ. N1-(5'-phosphoribosyl)adenosine-5'-monophosphate cyclohydrolase: purification and characterization of a unique metalloenzyme. Biochemistry 1999; 38:1537-46. [PMID: 9931020 DOI: 10.1021/bi982475x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
N1-(5'-Phosphoribosyl)adenosine-5'-monophosphate cyclohydrolase (HisI, PR-AMP cyclohydrolase) is a central enzyme in histidine biosynthesis catalyzing the hydrolysis of the N1-C6 bond of the purine substrate, a reaction unique to this pathway. A source of the recombinant monofunctional Methanococcus vannielii PR-AMP cyclohydrolase has been developed, and the first characterization of a purified form of the enzyme is reported. The enzyme has a native molecular weight of 31 200 as determined by analytical ultracentrifugation that agrees with the molecular mass determined by gel filtration (34 kDa) and a subunit molecular weight of 15 486 based on MALDI-MS. An unusual characteristic of the protein is the complexity observed on SDS-PAGE, and N-terminal amino acid sequence analysis of all the isolated constituents confirms their origin as PR-AMP cyclohydrolase. A highly conserved region of the amino acid sequence is implicated in the self-cleavage events of the protein and provides an explanation for the complexity of this protein. Bound to the enzyme is 1 equiv of Zn2+ that can be removed only by extended dialysis with 1,10-phenanthroline (Kd </= 10(-)9 M). Removal of the Zn2+ correlates with the loss of enzyme activity. The enzyme is reversibly inhibited by inclusion of EDTA in the assay mixture, demonstrating that free Mg2+ (Ks = 4.9 +/- 0.7 microM) is required for catalytic activity. Further evidence for a low-affinity binding site is indicated by the inhibitory effects of exogenous Zn2+ on enzyme activity. The pH dependence of the PR-AMP cyclohydrolase activity shows a single titration event in the kcat/Km profile with a pKa of 7.3 that is consistent with the functional role of a metal site in catalysis. These data are discussed in the context of the mechanism of other nucleotide hydrolases.
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Affiliation(s)
- R L D'Ordine
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907-1333, USA
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10
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Shimoni-Livny L, Glusker JP, Bock CW. Lone Pair Functionality in Divalent Lead Compounds. Inorg Chem 1998. [DOI: 10.1021/ic970909r] [Citation(s) in RCA: 773] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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11
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Petrovich RM, Jaffe EK. Magnetic resonance studies on the active site and metal centers of Bradyrhizobium japonicum porphobilinogen synthase. Biochemistry 1997; 36:13421-7. [PMID: 9341235 DOI: 10.1021/bi971642a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Porphobilinogen synthase (PBGS) is a metalloenzyme which catalyzes the asymmetric condensation of two molecules of 5-aminolevulinic acid (ALA) to form porphobilinogen. There are at least four types of PBGS, categorized according to metal ion usage. The PBGS from Bradyrhizobium japonicum requires Mg(II) in catalytic metal site A, has an allosteric Mg(II) in metal site C, and also contains an activating monovalent cation binding site [Petrovich et al. (1996) J. Biol. Chem. 271, 8692-8699]. 13C NMR and Mn(II) EPR have been used to probe the active site and Mg(II) binding sites of this 310 000 dalton protein. The 13C NMR chemical shifts of enzyme-bound product demonstrate that the chemical environment of porphobilinogen bound to B. japonicum PBGS is different from that of PBGS which contains Zn(II) rather than Mg(II) at the active site. Use of Mn(II) in place of Mg(II) broadens the NMR resonances of enzyme-bound porphobilinogen, providing evidence for a direct interaction between MnA and product at the active site. Prior characterization of the enzyme defined conditions in which the divalent cation occupies either the A or the C site. Mimicking these conditions allows Mn(II) EPR observation of either MnC or MnA. The EPR spectrum of MnC is significantly broader and less intense than "free" Mn(II), but relatively featureless. The EPR spectrum of MnA is broader still and more asymmetric than MnC. The EPR data indicate that the coordination spheres of the two metals are different.
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Affiliation(s)
- R M Petrovich
- Institute for Cancer Research, Fox Chase Cancer Center, 7701 Burholme Avenue, Philadelphia, Pennsylvania 19111, USA
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12
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Chapter 45 Vitamin B12. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s1569-2582(97)80106-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2023]
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13
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Petrovich RM, Litwin S, Jaffe EK. Bradyrhizobium japonicum porphobilinogen synthase uses two Mg(II) and monovalent cations. J Biol Chem 1996; 271:8692-9. [PMID: 8621501 DOI: 10.1074/jbc.271.15.8692] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Bradyrhizobium japonicum porphobilinogen synthase (B. japonicum PBGS) has been purified and characterized from an overexpression system in an Escherichia coli host (Chauhan, S., and O'Brian, M. R. (1995) J. Biol. Chem. 270, 19823-19827). B. japonicum PBGS defines a new class of PBGS protein, type IV (classified by metal ion content), which utilizes a catalytic MgA present at a stoichiometry of 4/octamer, an allosteric MgC present at a stoichiometry of 8/octamer, and a monovalent metal ion, K+. However, the divalent MgB or ZnB present in some other PBGS is not present in B. japonicum PBGS. Under optimal conditions, the Kd for MgA is <0.2 microM, and the Kd for MgC is about 40 microM. The response of B. japonicum PBGS activity to monovalent and divalent cations is mutually dependent and varies dramatically with pH. B. japonicum PBGS is also found to undergo a dynamic equilibrium between active multimeric species and inactive monomers under assay conditions, a kinetic characteristic not reported for other PBGSs. B. japonicum PBGS is the first PBGS that has been rigorously demonstrated to lack a catalytic ZnA. However, consistent with prior predictions, B. japonicum PBGS can bind Zn(II) (presumably as ZnA) at a stoichiometry of 4/octamer with a Kd of 200 microM; but this high concentration is outside a physiologically significant range.
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Affiliation(s)
- R M Petrovich
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA
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14
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Rhie G, Avissar YJ, Beale SI. Structure and expression of the Chlorobium vibrioforme hemB gene and characterization of its encoded enzyme, porphobilinogen synthase. J Biol Chem 1996; 271:8176-82. [PMID: 8626508 DOI: 10.1074/jbc.271.14.8176] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Plasmids containing DNA from the green photosynthetic bacterium Chlorobium vibrioforme complement a heme-requiring Escherichia coli hemB mutant that is deficient in porphobilinogen (PBG) synthase activity. PBG synthase activity was detected in extract of complemented cells but not in that of cells transformed with control plasmid. The sequence of the C. vibrioforme hemB gene predicts a HemB protein that contains 328 amino acids, has a molecular weight of 36,407, and is 53% identical to the homologous proteins of Synechocystis sp. PCC 6301 and Rhodobacter capsulatus. The response of C. vibrioforme PBG synthase to divalent metals is unlike that of any previously described PBG synthase; Mg2+ stimulates but is not required for activity, and Zn2+ neither stimulates nor is required. This response correlates with predicted sequences of two putative variable metal binding regions of C. vibrioforme HemB. The C. vibrioforme hemB open reading frame begins 1585 bases downstream from the end of the hemD open reading frame and is transcribed in the same direction as hemA, hemC, and hemD. However, hemB is not part of the same transcription unit as these genes, and the hemB transcript is approximately the same size as the hemB gene alone. Between hemD and hemB there is an intervening open reading frame that is oriented in the opposite direction and encodes a protein with a predicted amino acid sequence significantly similar to that of inositol monophosphatase, an enzyme that is not involved in tetrapyrrole biosynthesis. The gene order within hem gene clusters is highly conserved in phylogenetically diverse prokaryotic organisms. This conservation suggests that there are functional constraints on the relative order of the hem genes.
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Affiliation(s)
- G Rhie
- Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912, USA
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15
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Stolz M, Dörnemann D. Purification, metal cofactor, N-terminal sequence and subunit composition of a 5-aminolevulinic acid dehydratase from the unicellular green alga Scenedesmus obliquus, mutant C-2A'. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 236:600-8. [PMID: 8612634 DOI: 10.1111/j.1432-1033.1996.00600.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
5-Aminolevulinic acid dehydratase was purified to apparent homogeneity from Scenedesmus obliquus, mutant C-2A', starting with serial affinity chromatography according to Wang et al., followed by separation on DEAE-Cellulose DE 52, TSKgel Toyopearl HW-55 and FPLC on Mono Q. The enzyme was purified 117-fold compared with the initial crude soluble enzyme preparation and showed a final specific activity of 9.17 microkat/kg protein at pH 8.2 at a total recovery of 7%. Mg2+ was determined to be the metal cofactor of the enzyme. It can, to a certain extent, be substituted by other divalent cations. From the purified enzyme the first 15 amino acids of the N-terminus could be determined, showing a moderate similarity to 5-aminolevulinic acid dehydratases from spinach, pea, Escherichia coli and yeast. The molecular mass of the native protein was determined by gel filtration to be 282+/-5 kDa. 42+/-1 kDa were ascertained for the subunit size by SDS/PAGE. These investigations, supported by electron microscopy, revealed that the enzyme from Scenedesmus consists of six subunits arranged in a six-membered ring. Additionally, there is some evidence that two of the rings form a sandwich-like complex.
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Affiliation(s)
- M Stolz
- Fachbereich Biologie/Botanik, Philipps-Universität Marburg, Germany
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16
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Chemical synthesis of porphobilinogen and studies of its biosynthesis. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s1521-4478(06)80004-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Callahan SM, Cornell NW, Dunlap PV. Purification and properties of periplasmic 3':5'-cyclic nucleotide phosphodiesterase. A novel zinc-containing enzyme from the marine symbiotic bacterium Vibrio fischeri. J Biol Chem 1995; 270:17627-32. [PMID: 7615571 DOI: 10.1074/jbc.270.29.17627] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The 3':5'-cyclic nucleotide phosphodiesterase (CNP) of Vibrio fischeri, due to its unusual location in the periplasm, allows this symbiotic bacterium to utilize extracellular 3':5'-cyclic nucleotides (e.g. cAMP) as sole sources of carbon and energy, nitrogen, and phosphorus for growth. The enzyme was purified to apparent homogeneity by a four-step procedure: chloroform shock, ammonium sulfate precipitation, and chromotography on DEAE-Sephacel and Cibacron Blue 3GA-agarose. The active enzyme consists of a single polypeptide with a mass of 34 kDa. At 25 degrees C, it has a pH optimum of 8.25, a Km for cAMP of 73 microns, and a Vmax of 3700 mumol of cAMP hydrolyzed/min/mg protein (turnover number of 1.24 x 10(5)/min). The specific activity of the V. fischeri enzyme is approximately 20-fold greater than that of any previously characterized CNP when comparisons of activity are made at the same assay temperature. Activity increases with temperature up to 60 degrees C. The CNP contains 2 atoms of zinc/monomer, and zinc, copper, magnesium, and calcium can restore activity of the apoenzyme to varying degrees. The exceptional specific activity of the enzyme and its unusual location in the periplasm support proposals that the enzyme enables the bacterium to scavenge 3':5'-cyclic nucleotides in seawater and that the enzyme plays a role in cAMP-mediated host-symbiont interactions.
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Affiliation(s)
- S M Callahan
- Biology Department, Woods Hole Oceanographic Institution, Massachusetts 02543, USA
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18
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Avissar YJ, Moberg PA. The common origins of the pigments of life-early steps of chlorophyll biosynthesis. PHOTOSYNTHESIS RESEARCH 1995; 44:221-242. [PMID: 24307093 DOI: 10.1007/bf00048596] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/1994] [Accepted: 03/30/1995] [Indexed: 06/02/2023]
Abstract
The complex pathway of tetrapyrrole biosynthesis can be dissected into five sections: the pathways that produce 5-aminolevulinate (the C-4 and the C-5 pathways), the steps that transform ALA to uroporphyrinogen III, which are ubiquitous in the biosynthesis of all tetrapyrroles, and the three branches producing specialized end products. These end products include corrins and siroheme, chlorophylls and hemes and linear tetrapyrroles. These branches have been subjects of recent reviews. This review concentrates on the early steps leading up to uroporphyrinogen III formation which have been investigated intensively in recent years in animals, in plants, and in a wide range of bacteria.
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Affiliation(s)
- Y J Avissar
- Department of Biology, Rhode Island College, 02908, Providence, RI, USA
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19
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Abstract
Porphobilinogen is the monopyrrole precursor of all biological tetrapyrroles. The biosynthesis of porphobilinogen involves the asymmetric condensation of two molecules of 5-aminolevulinate and is carried out by the enzyme porphobilinogen synthase (PBGS), also known as 5-aminolevulinate dehydratase. This review documents what is known about the mechanism of the PBGS-catalyzed reaction. The metal ion constituents of PBGS are of particular interest because PBGS is a primary target for the environmental toxin lead. Mammalian PBGS contains two zinc ions at each active site. Bacterial and plant PBGS use a third metal ion, magnesium, as an allosteric activator. In addition, some bacterial and plant PBGS may use magnesium in place of one or both of the zinc ions of mammalian PBGS. These phylogenetic variations in metal ion usage are described along with a proposed rationale for the evolutionary divergence in metal ion usage. Finally, I describe what is known about the structure of PBGS, an enzyme which has as yet eluded crystal structure determination.
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Affiliation(s)
- E K Jaffe
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA
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20
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Matters GL, Beale SI. Structure and expression of the Chlamydomonas reinhardtii alad gene encoding the chlorophyll biosynthetic enzyme, delta-aminolevulinic acid dehydratase (porphobilinogen synthase). PLANT MOLECULAR BIOLOGY 1995; 27:607-617. [PMID: 7894023 DOI: 10.1007/bf00019326] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
cDNA clones for the alad gene encoding the chlorophyll biosynthetic enzyme ALA dehydratase (ALAD) from Chlamydomonas reinhardtii were isolated by complementation of an Escherichia coli ALAD mutant (hemB). The C. reinhardtii alad gene encodes a protein that has 50 to 60% sequence identity with higher plant ALADs, and includes a putative Mg(2+)-binding domain characteristic of plant ALADs. Multiple classes of ALAD cDNAs were identified which varied in the length of their 3'-untranslated region. Genomic Southern analysis, using an ALAD cDNA as a probe, indicates that it is a single-copy gene. This suggests that the differently sized ALAD cDNAS are not the products of separate genes, but that a primary ALAD transcript is polyadenylated at multiple sites. A time course determination of ALAD mRNA levels in 12-h light:12-h dark synchronized cultures shows a 7-fold increase in ALAD mRNA at 2 h into the light phase. The ALAD mRNA level gradually declines but continues to be detectable up to the beginning of the dark phase. ALAD enzyme activity increases 3-fold by 6 h into the light phase and remains high through 10 h. Thus, there is an increase in both ALAD mRNA level and ALAD enzyme activity during the light phase, corresponding to the previously observed increase in the rate of chlorophyll accumulation.
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Affiliation(s)
- G L Matters
- Division of Biology and Medicine, Brown University, Providence, Rhode Island
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Affiliation(s)
- J P Glusker
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111
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22
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Abstract
The haem biosynthesis pathway continues to provide surprises, from the first enzyme, 5-aminolaevulinic acid synthase, the mRNA of which contains an iron-responsive element, to the last, ferrochelatase, that contains an iron sulphur cluster. 5-Aminolaevulinate dehydratase from animals are zinc-dependent enzymes while those from plants require magnesium. The first X-ray structure of a haem synthesis enzyme, porphobilinogen deaminase, has not only yielded clues about the mechanism of tetrapyrrole assembly but has also provided insight into the molecular basis of the human disease acute intermittent porphyria. Evidence is growing to suggest that a previously unsuspected alternative haem pathway may exist.
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