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Thanh Ta D, Chiang CJ, Xuan Huang Z, Luu NL, Chao YP. High production of poly(3-hydroxybutyrate) in Escherichia coli using crude glycerol. BIORESOURCE TECHNOLOGY 2023:129315. [PMID: 37321309 DOI: 10.1016/j.biortech.2023.129315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/07/2023] [Accepted: 06/08/2023] [Indexed: 06/17/2023]
Abstract
Poly(3-hydroxybutyrate) (PHB) is a prominent bio-plastic and recognized as the potential replacement of petroleum-derived plastics. To make PHB cost-effective, the production scheme based on crude glycerol was developed using Escherichia coli. The heterogeneous synthesis pathway of PHB was introduced into the E. coli strain capable of efficiently utilizing glycerol. The central metabolism that links to the synthesis of acetyl-CoA and NADPH was further reprogrammed to improve the PHB production. Key genes were targeted for manipulation, involving those in glycolysis, the pentose phosphate pathway, and the tricarboxylic cycle. As a result, the engineered strain gained a 22-fold increase in the PHB titer. Finally, the fed-batch fermentation was conducted with the producer strain to give the PHB titer, content, and productivity reaching 36.3±3.0 g/L, 66.5±2.8%, and 1.2±0.1 g/L/h, respectively. The PHB yield on crude glycerol accounts for 0.3 g/g. The result indicates that the technology platform as developed is promising for the production of bio-plastics.
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Affiliation(s)
- Doan Thanh Ta
- Department of Chemical Engineering, Feng Chia University, 100 Wenhwa Road, Taichung 40724, Taiwan
| | - Chung-Jen Chiang
- Department of Medical Laboratory Science and Biotechnology, China Medical University, No. 91, Hsueh-Shih Road, Taichung 40402, Taiwan
| | - Zhu Xuan Huang
- Department of Chemical Engineering, Feng Chia University, 100 Wenhwa Road, Taichung 40724, Taiwan
| | - Nguyen Luan Luu
- Department of Chemical Engineering, Feng Chia University, 100 Wenhwa Road, Taichung 40724, Taiwan
| | - Yun-Peng Chao
- Department of Chemical Engineering, Feng Chia University, 100 Wenhwa Road, Taichung 40724, Taiwan; Department of Medical Research, China Medical University Hospital, Taichung 40447, Taiwan.
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Schubert C, Unden G. Fumarate, a central electron acceptor for Enterobacteriaceae beyond fumarate respiration and energy conservation. Adv Microb Physiol 2023; 82:267-299. [PMID: 36948656 DOI: 10.1016/bs.ampbs.2022.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
C4-dicarboxylates (C4-DCs) such as fumarate, l-malate and l-aspartate are key substrates for Enterobacteria such as Escherichia coli or Salmonella typhimurium during anaerobic growth. In general, C4-DCs are oxidants during biosynthesis, e.g., of pyrimidine or heme, acceptors for redox balancing, a high-quality nitrogen source (l-aspartate) and electron acceptor for fumarate respiration. Fumarate reduction is required for efficient colonization of the murine intestine, even though the colon contains only small amounts of C4-DCs. However, fumarate can be produced endogenously by central metabolism, allowing autonomous production of an electron acceptor for biosynthesis and redox balancing. Bacteria possess a complex set of transporters for the uptake (DctA), antiport (DcuA, DcuB, TtdT) and excretion (DcuC) of C4-DCs. DctA and DcuB exert regulatory functions and link transport to metabolic control through interaction with regulatory proteins. The sensor kinase DcuS of the C4-DC two-component system DcuS-DcuR forms complexes with DctA (aerobic) or DcuB (anaerobic), representing the functional state of the sensor. Moreover, EIIAGlc from the glucose phospho-transferase system binds to DctA and presumably inhibits C4-DC uptake. Overall, the function of fumarate as an oxidant in biosynthesis and redox balancing explains the pivotal role of fumarate reductase for intestinal colonization, while the role of fumarate in energy conservation (fumarate respiration) is of minor importance.
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Affiliation(s)
- Christopher Schubert
- Institute for Molecular Physiology (IMP), Microbiology and Biotechnology; Johannes Gutenberg-University, Mainz, Germany; Institute of Microbiology, ETH Zurich, Zurich, Switzerland.
| | - Gottfried Unden
- Institute for Molecular Physiology (IMP), Microbiology and Biotechnology; Johannes Gutenberg-University, Mainz, Germany.
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3
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Dharmarajan L, Kraszewski JL, Mukhopadhyay B, Dunten PW. Structure of an archaeal-type phosphoenolpyruvate carboxylase sensitive to inhibition by aspartate. Proteins 2011; 79:1820-9. [PMID: 21491491 DOI: 10.1002/prot.23006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 01/06/2011] [Accepted: 01/21/2011] [Indexed: 11/06/2022]
Abstract
The crystal structure of an archaeal-type phosphoenolpyruvate carboxylase from Clostridium perfringens has been determined based on X-ray data extending to 3 Å. The asymmetric unit of the structure includes two tetramers (each a dimer-of-dimers) of the enzyme. The precipitant, malonate, employed for the crystallization is itself a weak inhibitor of phosphoenolpyruvate carboxylase and a malonate molecule is seen in the active-site in the crystal structure. The allosteric binding sites for aspartate (an inhibitor) and glucose-6-phosphate (an activator) observed in the Escherichia coli and Zea mays phosphoenolpyruvate carboxylase structures, respectively, are not conserved in the C. perfringens structure. Aspartate inhibits the C. perfringens enzyme competitively with respect to the substrate, Mg(++.) phosphoenolpyruvate. A mechanism for inhibition is proposed based on the structure and sequence comparisons with other archaeal-type phosphoenolpyruvate carboxylases with differing sensitivity to inhibition by aspartate.
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Affiliation(s)
- Lakshmi Dharmarajan
- Virginia Bioinformatics Institute, Bioinformatics and Computational Biology Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
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4
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pH and base counterion affect succinate production in dual-phase Escherichia coli fermentations. J Ind Microbiol Biotechnol 2009; 36:1101-9. [PMID: 19484279 DOI: 10.1007/s10295-009-0594-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 05/11/2009] [Indexed: 10/20/2022]
Abstract
Succinate production was studied in Escherichia coli AFP111, which contains mutations in pyruvate formate lyase (pfl), lactate dehydrogenase (ldhA) and the phosphotransferase system glucosephosphotransferase enzyme II (ptsG). Two-phase fermentations using a defined medium at several controlled levels of pH were conducted in which an aerobic cell growth phase was followed by an anaerobic succinate production phase using 100% (v/v) CO(2). A pH of 6.4 yielded the highest specific succinate productivity. A metabolic flux analysis at a pH of 6.4 using (13)C-labeled glucose showed that 61% of the PEP partitioned to oxaloacetate and 39% partitioned to pyruvate, while 93% of the succinate was formed via the reductive arm of the TCA cycle. The flux distribution at a pH of 6.8 was also analyzed and was not significantly different compared to that at a pH of 6.4. Ca(OH)(2) was superior to NaOH or KOH as the base for controlling the pH. By maintaining the pH at 6.4 using 25% (w/v) Ca(OH)(2), the process achieved an average succinate productivity of 1.42 g/l h with a yield of 0.61 g/g.
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Ettema TJG, Ahmed H, Geerling ACM, van der Oost J, Siebers B. The non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase (GAPN) of Sulfolobus solfataricus: a key-enzyme of the semi-phosphorylative branch of the Entner-Doudoroff pathway. Extremophiles 2007; 12:75-88. [PMID: 17549431 DOI: 10.1007/s00792-007-0082-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Accepted: 03/28/2007] [Indexed: 11/25/2022]
Abstract
Archaea utilize a branched modification of the classical Entner-Doudoroff (ED) pathway for sugar degradation. The semi-phosphorylative branch merges at the level of glyceraldehyde 3-phosphate (GAP) with the lower common shunt of the Emden-Meyerhof-Parnas pathway. In Sulfolobus solfataricus two different GAP converting enzymes-classical phosphorylating GAP dehydrogenase (GAPDH) and the non-phosphorylating GAPDH (GAPN)-were identified. In Sulfolobales the GAPN encoding gene is found adjacent to the ED gene cluster suggesting a function in the regulation of the semi-phosphorylative ED branch. The biochemical characterization of the recombinant GAPN of S. solfataricus revealed that-like the well-characterized GAPN from Thermoproteus tenax-the enzyme of S. solfataricus exhibits allosteric properties. However, both enzymes show some unexpected differences in co-substrate specificity as well as regulatory fine-tuning, which seem to reflect an adaptation to the different lifestyles of both organisms. Phylogenetic analyses and database searches in Archaea indicated a preferred distribution of GAPN (and/or GAP oxidoreductase) in hyperthermophilic Archaea supporting the previously suggested role of GAPN in metabolic thermoadaptation. This work suggests an important role of GAPN in the regulation of carbon degradation via modifications of the EMP and the branched ED pathway in hyperthermophilic Archaea.
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Affiliation(s)
- Thijs J G Ettema
- Department of Molecular Evolution, Evolutionary Biology Center, Uppsala University, Norbyvägen 18C, 752 36 Uppsala, Sweden
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Lorentzen E, Hensel R, Knura T, Ahmed H, Pohl E. Structural Basis of allosteric regulation and substrate specificity of the non-phosphorylating glyceraldehyde 3-Phosphate dehydrogenase from Thermoproteus tenax. J Mol Biol 2004; 341:815-28. [PMID: 15288789 DOI: 10.1016/j.jmb.2004.05.032] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Revised: 05/19/2004] [Accepted: 05/21/2004] [Indexed: 11/28/2022]
Abstract
The non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase (GAPN) of the hyperthermophilic Archaeum Thermoproteus tenax is a member of the superfamily of aldehyde dehydrogenases (ALDH). GAPN catalyses the irreversible oxidation of glyceraldehyde 3-phosphate (GAP) to 3-phosphoglycerate in the modified glycolytic pathway of this organism. In contrast to other members of the ALDH superfamily, GAPN from T.tenax (Tt-GAPN) is regulated by a number of intermediates and metabolites. In the NAD-dependent oxidation of GAP, glucose 1-phosphate, fructose 6-phosphate, AMP and ADP increase the affinity for the cosubstrate, whereas ATP, NADP, NADPH and NADH decrease it leaving, however, the catalytic rate virtually unaltered. As we show here, the enzyme also uses NADP as a cosubstrate, displaying, however, unusual discontinuous saturation kinetics indicating different cosubstrate affinities and/or reactivities of the four active sites of the protein tetramer caused by cooperative effects. Furthermore, in the NADP-dependent reaction the presence of activators decreases the overall S0.5 and increases Vmax by a factor of 3. To explore the structural basis for the different effects of both pyridine nucleotides we solved the crystal structure of Tt-GAPN in complex with NAD at 2.2 A resolution and compared it to the binary Tt-GAPN-NADPH structure. Although both pyridine nucleotides show a similar binding mode, NADPH appears to be more tightly bound to the protein via the 2' phosphate moiety. Moreover, we present four co-crystal structures with the activating molecules glucose 1-phosphate, fructose 6-phosphate, AMP and ADP determined at resolutions ranging from 2.3 A to 2.6 A. These crystal structures reveal a common regulatory site able to accommodate the different activators. A phosphate-binding pocket serves as an anchor point ensuring similar binding geometry. The observed conformational changes upon activator binding are discussed in terms of allosteric regulation. Furthermore, we present a crystal structure of Tt-GAPN in complex with the substrate D-GAP at 2.3 A resolution, which allows us to analyse the structural basis for substrate binding, the mechanism of catalysis as well as the stereoselectivity of the enzymatic reaction.
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Affiliation(s)
- Esben Lorentzen
- European Molecular Biology Laboratory, Hamburg Outstation, Notkestr. 85, D-22603 Hamburg, Germany
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7
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Choi WE, Brader ML, Aguilar V, Kaarsholm NC, Dunn MF. The allosteric transition of the insulin hexamer is modulated by homotropic and heterotropic interactions. Biochemistry 1993; 32:11638-45. [PMID: 8218231 DOI: 10.1021/bi00094a021] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The allosteric behavior of the Co(II)-substituted insulin hexamer has been investigated using electronic spectroscopy to study the binding of different phenolic analogues and singly charged anions to effector sites on the protein. This work presents the first detailed, quantitative analysis of the ligand-induced T- to R-state allosteric transition of the insulin hexamer. Recent studies have established that there are two ligand binding processes which stabilize the R-state conformation of the Co(II)-substituted hexamer: the binding of cyclic organic molecules to the six protein pockets present in the Zn(II)-R6 insulin hexamer [Derewenda, U., Derewenda, Z., Dodson, E. J., Dodson, G. G., Reynolds, C. D., Smith, G. D., Sparks, C., & Swensen, D. (1989) Nature 338, 594-596] and the coordination of singly charged anions to the His(B10) metal sites [Brader, M.L., Kaarsholm, N.C., Lee, W.K., & Dunn, M.F. (1991) Biochemistry 30, 6636-6645]. The R6 insulin hexamer is stabilized by heterotropic interactions between the hydrophobic protein pockets and the coordination sites of the His(B10)-bound metal ions. The binding studies with 4-hydroxybenzamide, m-cresol, resorcinol, and phenol presented herein show that, in the absence of inorganic anions, the 4-hydroxybenzamide-induced transition, with a Hill number of 2.8, is the most cooperative, followed by m-cresol, phenol, and resorcinol with Hill numbers of 1.8, 1.4, and 1.2, respectively. The relative effectiveness of these ligands in shifting the allosteric equilibrium in favor of the Co(II)-R6 hexamer was found to be resorcinol > phenol > 4-hydroxybenzamide > m-cresol.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- W E Choi
- Department of Biochemistry-015, University of California, Riverside 92521-0129
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8
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Aguilar Z, Urbina JA. The phosphofructokinase of Trypanosoma (Schizotrypanum) cruzi: purification and kinetic mechanism. Mol Biochem Parasitol 1986; 21:103-11. [PMID: 2946951 DOI: 10.1016/0166-6851(86)90013-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The phosphofructokinase (ATP:D-fructose-6-phosphate 1-phosphotransferase, E.C.2.7.1.11) of Trypanosoma (Schizotrypanum) cruzi epimastigotes has been purified 180-fold, to apparent electrophoretic homogeneity, by differential centrifugation, gel filtration chromatography and anionic exchange chromatography. The minimum catalytic unit of the purified enzyme is a polypeptide of 17,000 +/- 1300 molecular weight, as shown by gel filtration chromatography and SDS-gel electrophoresis. Hanes-Woolf plots of initial rates and Mg-ATP or D-fructose-6-phosphate concentrations for varying values of the co-substrate concentration gave intersecting lines which indicate a sequential mechanism. No inhibition is observed at high Mg-ATP concentrations, confirming the result of a previous study using a partially purified enzyme. The pure enzyme displays both negative and positive cooperative kinetics at low (less than 0.8 mM) concentrations of D-fructose-6-phosphate, suggesting aggregation and/or activation phenomena induced by this substrate. Product inhibition studies at saturating and non-saturating concentrations of D-fructose-6-phosphate gave as the only compatible mechanism an iso-ordered bi-bi process with a probable order of entry to and exit from the active site being: D-fructose-6-phosphate followed by Mg-ATP and D-fructose-1,6-bisphosphate followed by Mg-ADP, respectively. The very important differences in both the structural and mechanistic aspects between this enzyme and its vertebrate and bacterial counterparts supports the notion of a highly unusual carbohydrate catabolism in this parasite.
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Coomes MW, Mitchell BK, Beezley A, Smith TE. Properties of an Escherichia coli mutant deficient in phosphoenolpyruvate carboxylase catalytic activity. J Bacteriol 1985; 164:646-52. [PMID: 3902793 PMCID: PMC214301 DOI: 10.1128/jb.164.2.646-652.1985] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A mutant Escherichia coli (Ppcc-) which was unable to grow on glucose as a sole carbon source was isolated. This mutant had very low levels of phosphoenolpyruvate carboxylase activity (approximately 5% of the wild type). Goat immunoglobulin G prepared against wild-type phosphoenolypyruvate carboxylase cross-reacted with the Ppcc- enzyme. The amount of enzyme protein in the mutant cells was similar to that found in wild-type cells, but it had greatly diminished specific activity. The catalytically less active mutant enzyme retained the ability to interact with fructose 1,6-bisphosphate, but did not exhibit stabilization of the tetrameric form by aspartate. The pI of the mutant protein was lower (4.9) than that of the wild-type protein (5.1). After electrophoresis and immunoblotting of the partially purified protein, several immunostaining bands were seen in addition to the main enzyme band. A novel method for showing that these bands represented proteolytic fragments of phosphoenolpyruvate carboxylase was developed.
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Ascencio J, Bowes G. Phosphoenolpyruvate carboxylase in Hydrilla plants with varying CO2 compensation points. PHOTOSYNTHESIS RESEARCH 1983; 4:151-170. [PMID: 24458452 DOI: 10.1007/bf00052377] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/1982] [Indexed: 06/03/2023]
Abstract
Incubation of the submersed aquatic macrophyte, Hydrilla verticillata Royle, for up to 4 weeks in growth chambers under winter-like or summer-like conditions produced high (130 to 150 μl CO2/1) and low (6 to 8 μl CO2/l) CO2 compensation points (Γ), respectively. The activities of both ribulose bisphosphate (RuBP) and phosphoenolpyruvate (PEP) carboxylases increased upon incubation but the major increase was in the activity of PEP carboxylase under the summer-like conditions. This reduced the ratio of RuBP/PEP carboxylases from 2.6 in high Γ plants to 0.2 in low Γ plants. These ratios resemble the values in terrestrial C3 and C4 species, respectively.Kinetic measurements of the PEP carboxylase activity in high and low Γ plants indicated the Vmax was up to 3-fold greater in the low Γ plants. The Km (HCO3 (-)) values were 0.33 and 0.22 mM for the high and low Γ plants, respectively. The Km (PEP) values for the high and low Γ plants were 0.23 and 0.40 mM, respectively; and PEP exhibited cooperative effects. Estimated Km (Mg(2+)) values were 0.10 and 0.22 mM for the high and low Γ plants, respectively.Malate inhibited both PEP carboxylase types similarly. The enzyme from low Γ plants was protected by malate from heat inactivation to a greater extent than the enzyme from high Γ plants. The results indicated that C4 acid inhibition and protection were not reliable methods to distinguish C3 and C4 PEP carboxylases. The PEP carboxylase from low Γ plants was inhibited more by NaCl than that from hight Γ plants. These analyses indicated that Hydrilla PEP carboxylases had intermediate characteristics between those of terrestrial C3 and C4 species with the low Γ enzyme being different from the high Γ enzyme, and closer to a C4 type.
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Affiliation(s)
- J Ascencio
- Department of Botany, University of Florida, Gainesville, FA, USA
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Ascencio J, Bowes G. Phosphoenolpyruvate carboxylase in Hydrilla plants with varying CO2 compensation points. PHOTOSYNTHESIS RESEARCH 1983; 4:151-170. [PMID: 24458395 DOI: 10.1007/bf00041811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/1983] [Indexed: 06/03/2023]
Abstract
Incubation of the submersed aquatic macrophyte, Hydrilla vertieillata Royle, for up to 4 weeks in growth chambers under winter-like or summer-like conditions produced high (130 to 150 μl CO2/l) and low (6 to 8 μl CO2/l) CO2 compensation points (Γ), respectively. The activities of both ribulose bisphosphate (RuBP) and phosphoenolpyruvate (PEP) carboxylases increased upon incubation but the major increase was in the activity of PEP carboxylase under the summer-like conditions. This reduced the ratio of RuBP/PEP carboxylases from 2.6 in high Γ plants to 0.2 in low Γ plants. These ratios resemble the values in terrestrial C3 and C4 species, respectively.Kinetic measurements of the PEP carboxylase activity in high and low Γ plants indicated the Vmax was up to 3-fold greater in the low Γ plants. The Km (HCO3 (-)) values were 0.33 and 0.22 mM for the high and low Γ plants, respectively. The Km (PEP) values for the high and low Γ plants were 0.23 and 0.40 mM, respectively; and PEP exhibited cooperative effects. Estimated Km (Mg(2+)) values were 0.10 and 0.22 mM for the high and low Γ plants, respectively.Malate inhibited both PEP carboxylase types similarly. The enzyme from low Γ plants was protected by malate from heat inactivation to a greater extent than the enzyme from high Γ plants. The results indicated that C4 acid inhibition and protection were not reliable methods to distinguish C3 and C4 PEP carboxylases. The PEP carboxylase from low Γ plants was inhibited more by NaCl than that from high Γ plants. These analyses indicated that Hydrilla PEP carboxylases had intermediate characteristics between those of terrestrial C3 and C4 species with the low Γ enzyme being different from the high Γ enzyme, and closer to a C4 type.
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Affiliation(s)
- J Ascencio
- Department of Botany, University of Florida, Gainesville, FA, USA
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Hedlund B, Grynfarb M, Bartfai T. Two ligands may bind simultaneously to the muscarine receptor. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1982; 320:3-13. [PMID: 6896905 DOI: 10.1007/bf00499064] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Competition between 3H-3-quinuclidinyl benzilate (2 and 18 nM) and varying concentrations of antagonists (4-N-methyl piperidinyl benzilate (4-NMPB), atropine, scopolamine and pirenzepine (0-1000 nM) and agonists (acetylcholine, carbamylcholine, oxotremorine and pilocarpine (0.10(-10) to 10(-2) M)) was studied. Inhibition of specific 3H-3-quinuclidinyl benzilate binding was evaluated by Dixon plots which for both competing agonists and antagonists showed deviations from linearity. The best nonlinear least square fit to the Dixon plots was offered by a hyperbola, parabola or a straight line, depending on the ligand used. The data support a model of equilibrium binding which assumes that 3H-3-quinuclidinyl benzilate and one competing ligand molecule may simultaneously bind to the receptor at high concentrations of the competing ligand.
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Takahashi K, Weiner H. Nicotinamide adenine dinucleotide activation of the esterase reaction of horse liver aldehyde dehydrogenase. Biochemistry 1981; 20:2720-6. [PMID: 7248246 DOI: 10.1021/bi00513a003] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The esterase reaction catalyzed by horse liver aldehyde dehydrogenase is activated with NAD(H) by factors of 2 under a Vmax assay and of 6.8 at low ester concentrations (Feldman, R. I., & Weiner, H. (1972) J. Biol. Chem. 247, 267-272). Stopped-flow experiments suggested that an initial burst of 0.4 mol followed by a second burst of 1 mol of nitrophenol per mol of tetrameric enzyme occurred in the absence of NAD, while the magnitudes increased to 2 and 4 mol/mol of enzyme in its presence. If the enzyme was incubated for 1 min with NAD, the burst phase was 4 mol/mol of enzyme. Nonlinear Lineweaver--Burk plots were found in the absence and presence of NAD, but incubation with NAD for 1 min abolished the biphasic response. Mg2+ ions activate the dehydrogenase reaction of horse liver aldehyde dehydrogenase (Takahashi, K., & Weiner, H. (1980) J. Biol. Chem. 255, 8206-8209). The metal neither increased the esterase reaction nor affected the NAD activation. The rate-limiting step for the esterase reaction was thought to be the formation of an acyl intermediate, while that for the dehydrogenase reaction was deacylation (Weiner, H., Hu, J. H. J., & Sanny, C. G. (1976) J. Biol. Chem. 251, 3853-3855). Finding that a full burst exists for the esterase reaction in the presence of NAD shows that the deacylation step or product dissociation can become rate limiting. The major kinetic alteration produced by NAD is to increase the rate of acylation while not affecting deacylation. The presence of NAD appears to activate the attack of the active-site nucleophile on the carbonyl group of the substrate.
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14
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Infante JP, Houghton GE, Kinsella JE. A novel kinetic mechanism explaining the non-hyperbolic behavior of metal activated enzymes. Case of choline kinase from rat liver. J Theor Biol 1980; 86:177-201. [PMID: 6257986 DOI: 10.1016/0022-5193(80)90074-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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15
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16
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Hansen EJ, Juni E. Properties of mutants of Escherichia coli lacking malic dehydrogenase and their revertants. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(18)50799-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Abstract
Gonorrhea has been known since antiquity. Today, this disease is the most commonly reported infectious disease in the U.S. The natural environment of the etiological agent, Neisseria gonorrhoeae, is man. In this host, the organism usually parasitizes mucosal surfaces populated by columnar epithelial cells. Under certain conditions, the gonococcus may disseminate or spread to adjacent organs. The gonococcus is well adapted to its environment and is a successful parasite. Until recently, gonococci were uniformly sensitive to penicilin. However, a plasmid encoding beta-lactamase has been identified in some isolates. Most strains exhibit specific requirements for various amino acids, vitamins, purines, and pyrimidines. Only glucose, pyruvate, and lactate are utilized as sources of energy. Glucose is dissimilated by a combination of the Entner-Doudoroff and pentose phosphate pathways. A tricarboxylic acid cycle is also present and active under certain conditions. Structurally, the cell envelope of the gonococcus resembles that of a typical Gram-negative bacterium. Gonococci are highly autolytic, especially in older cultures or after depletion of the energy source. Autolysis is not due solely to peptidoglycan hydrolysis, but appears to involve a destabilization of the outer membrane as well. Cell surface components such as pili, lipopolysaccharide, outer membrane proteins, and a capsule are associated with the virulence and pathogenicity of this organism.
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18
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Christopherson RI, Finch LR. Response of the pyrimidine pathway of Escherichia coli K 12 to exogenous adenine and uracil. EUROPEAN JOURNAL OF BIOCHEMISTRY 1978; 90:347-58. [PMID: 361403 DOI: 10.1111/j.1432-1033.1978.tb12611.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The effect of exogenous adenine or uracil upon the de novo pathway for synthesis of pyrimidine nucleotides in Escherichia coli K12 was investigated. Parameters studied were levels of the enzymes carbamoyl phosphate synthase (EC 2.7.2.9), aspartate carbamoyltransferase (EC 2.1.3.2) and orotate phosphoribosyltransferase (EC 2.4.2.10) and the intermediates carbamoyl phosphate, aspartate and orotate, together with the contributions of exogenous uracil and aspartate to intracellular pyrimidine nucleotide. Taken with earlier data [Bagnara, A.S. & Finch, L. R. (1974) Eur. J. Biochem- 41, 421--430] on contents of UTP, CTP and 5-phosphoribosyl 1-diphosphate in cultures of this strain after the addition of adenine or uracil, the results obtained provide new insights into the regulatory mechanisms operating on the pathway in vivo. These insights enable evaluation of the contributions of such factors as limitation for a substrate, feed-back allosteric control by end products and enzyme repression/depression mechanisms. The evidence presented indicates that depressed levels of orotate phosphoribosyltransferase in E. coli K12 result in the wasteful ultilization of asparatate for excess synthesis of pyrimidine nucleotide precursors during balanced growth of the strain in minimal medium. Exogenous adenine increases the excessive accumulation of these precursors by lowering the intracellular content of 5-phosphoribosyl 1-diphosphate (Bagnara and Finch, 1974). This causes a decrease in the conversion of orotate to orotidine 5'-monophosphate, thus lowering the utilization or orotate and its precursors for synthesis of pyrimidine nucleotides. Further, since the contents of these nucleotide end products are thereby decreased (Bagnara nad Finch, 1974), theri feed-back on the early steps in the pathway is diminished and the production of the precursors is increased. It is postulated that growth of E. coli K12 under these conditions is limited by a compound that is metabolically related to precursors to aspartate.
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Abstract
The kinetic properties of purified smooth muscle myosin, free of actin, have been examined. Analysis of the steady-state kinetic data revealed an intermediary plateau region on the substrate saturation curves. In addition, these data, when analyzed by Hill and Lineweaver and Burk plots, indicate both positive and negative cooperativity, suggesting at least four substrate binding sites. The plateau region was abolished when the kinetic measurements were made at pH 5.5 and 9.0. Both positive and negative cooperative effects were absent at pH 9.0 and hyperbolic kinetics was observed. In contrast, at pH 5.5, although the plateau region was abolished, the enzyme exhibited positive cooperativity of substrate binding. When either heated or urea treated enzyme was used for kinetic measurements: (i) the plateau region shifted toward higher substrate concentration range; (ii) the cooperativity of binding sites was lost at low substrate concentrations but was instead seen at higher concentrations; and (iii) the Vmax was doubled. These data have been interpreted as due to ligand-induced conformational changes in the enzyme according to J. Teipel and D. E. Koshland, Jr. (1969).
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Hill CM, Waight RD, Bardsley WG. Dose any enzyme follow the Michaelis-Menten equation? Mol Cell Biochem 1977; 15:173-8. [PMID: 887080 DOI: 10.1007/bf01734107] [Citation(s) in RCA: 79] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A literature search has been conducted to see to what extent steady-state kinetics studies in the period 1965-1976 have revealed deviations from Michaelis-Menten kinetics. It was found that over 800 enzymes have been reported as giving complex curves for a variety of reasons and a group by group classification of all these enzymes has been carried out listing all the types of variations reported and the authors' explanations. In addition, for highly complex curves, we have determined the minimum degree of the rate equation. There were very few determined attempts to demonstrate adherence to the Michaelis-Menten equation over a wide variety of experimental conditions and substrate concentration and almost invariably detailed experimental work revealed unsuspected complexities. For these reasons, it is concluded that the assumption that most enzymes follow the Michaelis-Menten equation can not be supported by an appeal to the literature.
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Abstract
The enzymatic carboxylation of phosphoenolpyruvate by cell-free extracts of Neisseria gonorrhoeae was examined and determined to be similar to the reaction catalyzed by phosphoenolpyruvate carboxylase (PEPC). This was shown by the irreversibility of the reaction and nucleotide independency. The enzyme was found to have some characteristics different from the other bacterial PEPCs reported. The enzyme showed catalytic activity in the presence of cobalt ions as well as magnesium and manganese ions, was not inhibited by succinate in fresh extracts, and displayed a low Michaelis constant for bicarbonate (0.27 mM), as compared with other PEPCs. The significance of this low Michaelis constant is discussed with respect to the growth of the organism and the importance of this enzyme to protein and nucleic acid synthesis.
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22
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Regulation of glutaminase B in Escherichia coli. I. Purification, properties, and cold lability. J Biol Chem 1976. [DOI: 10.1016/s0021-9258(17)33459-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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23
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Roehl RA, Vinopal RT. Lack of glucose phosphotransferase function in phosphofructokinase mutants of Escherichia coli. J Bacteriol 1976; 126:852-60. [PMID: 177406 PMCID: PMC233222 DOI: 10.1128/jb.126.2.852-860.1976] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phosphofructokinase (pfkA) mutants of Escherichia coli are impaired in growth on all carbon sources entering glycolysis at or above the level of fructose 6-phosphate (nonpermissive carbon sources), but growth is particularly slow on sugars, such as glucose, which are normally transported and phosphorylated by the phosphoenolpyruvate, (PEP)-dependent phosphotransferase system (PTS).
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Levitzki A, Koshland DE. The role of negative cooperativity and half-of-the-sites reactivity in enzyme regulation. CURRENT TOPICS IN CELLULAR REGULATION 1976; 10:1-40. [PMID: 1253620 DOI: 10.1016/b978-0-12-152810-2.50008-5] [Citation(s) in RCA: 123] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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25
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Hollander PM, Bartfai T, Gatt S. Studies on the reaction mechanism of DT diaphorase. Intermediary plateau and trough regions in the initial velocity vs substrate concentration curves. Arch Biochem Biophys 1975; 169:568-76. [PMID: 170867 DOI: 10.1016/0003-9861(75)90201-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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26
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Hollander PM, Ernster L. Studies on the reaction mechanism of DT diaphorase. Action of dead-end inhibitors and effects of phospholipids. Arch Biochem Biophys 1975; 169:560-7. [PMID: 52345 DOI: 10.1016/0003-9861(75)90200-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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27
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Saski R, Pizer LI. Regulatory properties of purified 3-phosphoglycerate dehydrogenase from Bacillus subtilis. EUROPEAN JOURNAL OF BIOCHEMISTRY 1975; 51:415-27. [PMID: 168067 DOI: 10.1111/j.1432-1033.1975.tb03941.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
3-Phosphoglycerate dehydrogenase (3-phosphoglycerate:NAD oxidoreductase, EC. 1.1.1.95) was purified from Bacillus subtilis by conventional methods. The final preparation was homogeneous by electrophoretic analysis and had a sedimentation constant of 6.3 S. On the basis of gel filtration data the enzyme had a molecular weight of about 166000. The plot of velocity versus phosphoglycerate concentration was biphasic while similar plots for hydroxypyruvate phosphate and NADH were the conventional hyperbolic type. The enzyme was specifically inhibited by serine. The inhibition was time dependent, requiring several minutes incubation before a constant level of inhibition was achieved. Serine inhibition was of the "mixed type" with respect to 3-phosphoglycerate and Hill plots of these data had slopes that approached 2. Desensitization of the enzyme to serine inhibition was achieved by incubation in the absence of dithiothreitol. The desensitized enzyme was different from the native enzyme in fluoresence properties, sedimentation characteristics and in the absence of the biphasic phosphoglycerate saturation curve. Evidence was obtained for the participation of sulphydryl groups in the changes in protein structure responsible for serine inhibition as well as the dehydrogenase activity of the enzyme.
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Gold EW, Smith TE. Escherichia coli phosphoenolpyruvate carboxylase: effect of allosteric inhibitors on the kinetic parameters and sedimentation behavior. Arch Biochem Biophys 1974; 164:447-55. [PMID: 4618077 DOI: 10.1016/0003-9861(74)90054-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Kurganov BI, Kagan ZS, Dorozhko AI, Yakovlev VA. Kinetic manifestations of allosteric interactions in models of regulatory enzymes with "indirect" co-operativity. J Theor Biol 1974; 47:1-41. [PMID: 4459575 DOI: 10.1016/0022-5193(74)90096-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Vetterlein D, Cassman M. Different expressions of cooperativity in the kinetics of two forms of cytoplasmic malic dehydrogenase. Biochemistry 1974; 13:3243-50. [PMID: 4366944 DOI: 10.1021/bi00713a009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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31
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Stroinski A, Pawelkiewicz J, Johnson BC. Allosteric interactions in glycerol dehydratase. Purification of enzyme and effects of positive and negative cooperativity for glycerol. Arch Biochem Biophys 1974; 162:321-30. [PMID: 4407304 DOI: 10.1016/0003-9861(74)90189-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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32
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Gelb WG, Brandts JF, Nordin JH. Changes in sulfhydryl groups of honeybee glyceraldehyde phosphate dehydrogenase associated with generation of the intermediate plateau in its saturation kinetics. Biochemistry 1974; 13:280-7. [PMID: 4358941 DOI: 10.1021/bi00699a008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Cooperative Interactions in the Binding of Allosteric Effectors to Phosphoenolpyruvate Carboxylase. J Biol Chem 1974. [DOI: 10.1016/s0021-9258(19)43109-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Silverstein R, Willis MS. Concerted Regulation in Vitro of Phosphoenolpyruvate Carboxylase from Escherichia coli. J Biol Chem 1973. [DOI: 10.1016/s0021-9258(19)43147-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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35
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Shematek EM, Arfin SM, Diven WF. A kinetic study of -acetohydroxy acid isomeroreductase from Salmonella typhimurium. Arch Biochem Biophys 1973; 158:132-8. [PMID: 4147080 DOI: 10.1016/0003-9861(73)90605-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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36
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Coombs J, Baldry CW, Bucke C. The C-4 pathway in Pennisetum purpureum : I. The allosteric nature of PEP carboxylase. PLANTA 1973; 110:95-107. [PMID: 24474337 DOI: 10.1007/bf00384832] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/1972] [Indexed: 06/03/2023]
Abstract
Phosphoenol pyruvate (PEP) carboxylase has been partially purified from leaves of the C-4 tropical grass Pennisetum purpureum and shown to have allosteric properties. When initial velocities of incorporation of (14)C from NaH(14)CO3 into oxaloacetate were determined as a function of concentration of either HCO3-or Mg(2+) typical Michaelis-Menten kinetics were observed. Both Lineweaver-Burk and Hill plots were linear with values of n (interaction coefficients) of about one. Sigmoid Michaelis-Menten plots were obtained with PEP as the variable substrate. Following (NH4)2SO4 fractionation and DEAE-cellulose chromatography Lineweaver-Burk plots were concave upwards and Hill plots gave n values of two. With enzyme purified further by Sephadex G-200 chromatography Lineweaver-Burk plots were concave downwards and Hill plots gave values of n of 0.5 at low concentrations of PEP increasing to about 4 at high concentrations of PEP. Enzyme activity was modified by inclusion of glucose-6-phosphate (G6P) in the assay mixtures. When the eoncentration of G6P exceeded that of PEP, the initial velocity tended towards zero. When the concentration of G6P equalled that of PEP activity was increased. When the concentration of PEP exceeded that of G6P, the velocity approached that recorded in control samples at saturating concentrations of PEP. The rate of reaction was also increased on addition of NADH, and decreased by oxaloacetate and malate.
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Affiliation(s)
- J Coombs
- Group Research and Development, Philip Lyle Memorial Research Laboratory, Tate and Lyle Ltd., P.O. Box 68, RG6 2BX, Reading, Berks, UK
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Thorner JW, Paulus H. Catalytic and Allosteric Properties of Glycerol Kinase from Escherichia coli. J Biol Chem 1973. [DOI: 10.1016/s0021-9258(19)43821-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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38
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Ting IP, Osmond C. Activation of plant p-enolpyruvate carboxylases by glucose-6-phosphate: A particular role in crassulacean acid metabolism. ACTA ACUST UNITED AC 1973. [DOI: 10.1016/0304-4211(73)90064-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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39
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Kagan ZS, Dorozhko AI. pH-dependent intermediate plateaux in the kinetics of the reaction catalyzed by "biosynthetic" L-threonine dehydratase of Escherichia coli K-12. BIOCHIMICA ET BIOPHYSICA ACTA 1973; 302:110-28. [PMID: 4571178 DOI: 10.1016/0005-2744(73)90014-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Silverstein R. Kinetic studies of acetyl coenzyme A activated phosphoenolpyruvate carboxylase: reverse effects with a fatty acid. BIOCHIMICA ET BIOPHYSICA ACTA 1972; 258:626-36. [PMID: 4551567 DOI: 10.1016/0005-2744(72)90254-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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42
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McDaniel HG, Siu PM. Purification and characterization of phosphoenolpyruvate carboxylase from Plasmodium berghei. J Bacteriol 1972; 109:385-90. [PMID: 4621631 PMCID: PMC247289 DOI: 10.1128/jb.109.1.385-390.1972] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Phosphoenolpyruvate (PEP) carboxylase was purified over 400-fold from Plasmodium berghei. The purified enzyme was stable in 0.4 m potassium phosphate buffer (pH 7.4) containing 0.5 m glucose, 1 mm ethylenediaminetetraacetic acid (EDTA), and 1 mm MgCl(2). It had a molecular weight of 280,000 determined by sucrose density gradient centrifugation in this buffer, but it aggregated and was unstable in the presence of different salts or a more dilute solution of potassium phosphate. The K(m) for PEP was 2.6 mm and that for Mg(2+) was 1.3 mm. The K(m) for bicarbonate was 2 mm. Citrate, nucleotides, and EDTA inhibited the PEP carboxylase of P. berghei by decreasing the concentration of free magnesium ions, but acetyl-coenzyme A, fructose-1,6-diphosphate, and aspartate did not influence its activity. A chloroquine concentration of 1.8 x 10(-4)m inhibited the enzyme 50%.
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Kelly GJ, Turner JF. Cooperativity in pea-seed phosphofructokinase. BIOCHIMICA ET BIOPHYSICA ACTA 1971; 242:559-65. [PMID: 4258631 DOI: 10.1016/0005-2744(71)90149-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Nakae T, Nikaido H. Multiple Molecular Forms of Uridine Diphosphate Glucose Pyrophosphorylase from Salmonella typhimurium. J Biol Chem 1971. [DOI: 10.1016/s0021-9258(18)62024-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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47
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Liao CL, Atkinson DE. Regulation at the phosphoenolpyruvate branchpoint in Azotobacter vinelandii: phosphoenolpyruvate carboxylase. J Bacteriol 1971; 106:31-6. [PMID: 5551640 PMCID: PMC248640 DOI: 10.1128/jb.106.1.31-36.1971] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Phosphoenolpyruvate carboxylase (EC 4.1.1.31) from Azotobacter vinelandii, like the corresponding enzyme from other organisms, is activated by acetyl coenzyme A and inhibited by l-aspartate. Both modifiers affect primarily the affinity of the enzyme for phosphoenolpyruvate. This is the first enzyme with a strictly anaplerotic (intermediate-replacing) function to be tested for response to the adenylate energy charge; it is entirely insensitive to variation in charge. The results suggest that carboxylation of phosphoenolpyruvate in this organism is controlled by negative feedback from aspartate and by the stimulatory effect of acetyl coenzyme A. The adenylate energy charge may be expected to affect the rate of this reaction indirectly through its effects on the concentrations of acetyl coenzyme A and l-aspartate.
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Mukerji SK, Ting IP. Phosphoenolpyruvate carboxylase isoenzymes: separation and properties of three forms from cotton leaf tissue. Arch Biochem Biophys 1971; 143:297-317. [PMID: 4327242 DOI: 10.1016/0003-9861(71)90212-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Forrester LJ, Siu PM. P-enolpyruvate carboxylase from Plasmodium berghei. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1971; 38:73-85. [PMID: 4322552 DOI: 10.1016/0305-0491(71)90286-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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50
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