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George Cooper - One of the best experts on this subject based on the ideXlab platform.
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enantiomer excesses of rare and common Sugar derivatives in carbonaceous meteorites
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: George Cooper, Andro C RiosAbstract:Abstract Biological polymers such as nucleic Acids and proteins are constructed of only one—the d or l—of the two possible nonsuperimposable mirror images (enantiomers) of selected organic compounds. However, before the advent of life, it is generally assumed that chemical reactions produced 50:50 (racemic) mixtures of enantiomers, as evidenced by common abiotic laboratory syntheses. Carbonaceous meteorites contain clues to prebiotic chemistry because they preserve a record of some of the Solar System’s earliest (∼4.5 Gy) chemical and physical processes. In multiple carbonaceous meteorites, we show that both rare and common Sugar monoAcids (aldonic Acids) contain significant excesses of the d enantiomer, whereas other (comparable) Sugar Acids and Sugar alcohols are racemic. Although the proposed origins of such excesses are still tentative, the findings imply that meteoritic compounds and/or the processes that operated on meteoritic precursors may have played an ancient role in the enantiomer composition of life’s carbohydrate-related biopolymers.
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Enantiomer Ratios of Meteoritic Sugar Derivatives
2012Co-Authors: George CooperAbstract:Carbonaceous meteorites contain a diverse suite of soluble organic compounds. Studies of these compounds reveal the Solar System's earliest organic chemistry. Among the classes of organic compounds found in meteorites are keto Acids (pyruvic acid, etc.), hydroxy tricarboxylic Acids (1), amino Acids, amides, purines and pyrimidines [2-3]. The Murchison and Murray meteorites are the most studied for soluble and insoluble organic compounds and organic carbon phases. The majority of (indigenous) meteoritic compounds are racemic, (i.e., their DjL enantiomer ratios are 50:50). However, some of the more unusual (non-protein) amino Acids contain slightly more of one enantiomer (usually the L) than the other [4, 5]. This presentation focuses on the enantiomer analyses of three to six-carbon (3C to 6C) meteoritic Sugar Acids. The molecular and enantiomer analysis of corresponding Sugar alcohols will also be discussed. Detailed analytical procedures for Sugar-acid enantiomers have been described [6].
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Enantiomer Ratios of Meteoritic Sugar Derivatives
2012Co-Authors: George CooperAbstract:Carbonaceous meteorites contain a diverse suite of soluble organic compounds. Studies of these compounds reveal the Solar System's earliest organic chemistry. Among the classes of organic compounds found in meteorites are keto Acids (pyruvic acid, etc.), hydroxy tricarboxylic Acids (1), amino Acids, amides, purines and pyrimidines. The Murchison and Murray meteorites are the most studied for soluble and insoluble organic compounds and organic carbon phases. The majority of (indigenous) meteoritic compounds are racemic, (i.e., their D/L enantiomer ratios are 50:50). However, some of the more unusual (non-protein) amino Acids contain slightly more of one enantiomer (usually the L) than the other. This presentation focuses on the enantiomer analyses of three to six-carbon (3C to 6C) meteoritic Sugar Acids. The molecular and enantiomer analysis of corresponding Sugar alcohols will also be discussed. Detailed analytical procedures for Sugar-acid enantiomers have been described. Results of several meteorite analyses show that glyceric acid is consistently racemic (or nearly so) as expected of non-biological mechanisms of synthesis. Also racemic are 4-C deoxy Sugar Acids: 2-methyl glyceric acid; 2,4-dihydroxybutyric acid; 2,3-dihydroxybutyric acid (two diastereomers); and 3,4-dihydroxybutyric acid. However, a 4C acid, threonic acid, has never been observed as racemic, i.e., it possesses a large D excess. In several samples of Murchison and one of GRA 95229 (possibly the most pristine carbonaceous meteorite yet analyzed) threonic acid has nearly the same D enrichment. In Murchison, preliminary isotopic measurements of individual threonic acid enantiomers point towards extraterrestrial sources of the D enrichment. Enantiomer analyses of the 5C mono-Sugar Acids, ribonic, arabinonic, xylonic, and lyxonic also show large D excesses. It is worth noting that all four of these Acids (all of the possible straight-chained 5C Sugar Acids) are present in meteorites, including the rare lyxonic acid, and their relative abundances are in equilibrium proportions. In addition (in contrast to the above D-only excesses), some of the above Acids are found in biology as the L enantiomer. Whether rare are common, all of the 6C Sugar Acids that are present in sufficient amounts to allow enantiomer analysis (Mannonic, gluconic, altronic, talonic, idonic, gulonic, and galactonic) also, apparently, possess significant D excesses.
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Gas chromatography–mass spectrometry resolution of Sugar acid enantiomers on a permethylated β-cyclodextrin stationary phase
Journal of Chromatography A, 2009Co-Authors: George Cooper, Minakshi Sant, Cynthia AsiyoAbstract:Analysis of compounds in meteorites revealed a need to simultaneously characterize multiple enantiomers of Sugar Acids (aldonic Acids) present in trace amounts. Analyses by gas chromatography-mass spectrometry demonstrated that all but two of the three-carbon through six-carbon straight-chained Sugar acid enantiomer pairs could be resolved using a single derivatization procedure and one set of GC parameters. Compounds were analyzed as their ethyl ester/O-triflouroacetyl, isopropyl ester/O-triflouroacetyl and isopropyl ester/O-pentafluoropropionyl derivatives on a capillary column containing permethylated β-cyclodextrin (Chirasil-Dex CB) as the stationary phase. Characteristic mass fragments are related to the ester groups while several ions are also common to derivatized monosaccharides.
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Gas chromatography–mass spectrometry resolution of Sugar acid enantiomers on a permethylated β-cyclodextrin stationary phase
Journal of chromatography. A, 2009Co-Authors: George Cooper, Minakshi Sant, Cynthia AsiyoAbstract:Analysis of compounds in meteorites revealed a need to simultaneously characterize multiple enantiomers of Sugar Acids (aldonic Acids) present in trace amounts. Analyses by gas chromatography-mass spectrometry demonstrated that all but two of the three-carbon through six-carbon straight-chained Sugar acid enantiomer pairs could be resolved using a single derivatization procedure and one set of GC parameters. Compounds were analyzed as their ethyl ester/O-triflouroacetyl, isopropyl ester/O-triflouroacetyl and isopropyl ester/O-pentafluoropropionyl derivatives on a capillary column containing permethylated beta-cyclodextrin (Chirasil-Dex CB) as the stationary phase. Characteristic mass fragments are related to the ester groups while several ions are also common to derivatized monosaccharides.
Anu Koivula - One of the best experts on this subject based on the ideXlab platform.
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Characterization and mutagenesis of two novel iron–sulphur cluster pentonate dehydratases
Applied Microbiology and Biotechnology, 2016Co-Authors: Martina Andberg, Mervi Toivari, Merja Penttilä, Niina Aro-karkkainen, Paul Carlson, Merja Oja, Sophie Bozonnet, Nina Hakulinen, Michael O’donohue, Anu KoivulaAbstract:We describe here the identification and characterization of two novel enzymes belonging to the IlvD/EDD protein family, the D-xylonate dehydratase from Caulobacter crescentus , Cc XyDHT, (EC 4.2.1.82), and the L-arabonate dehydratase from Rhizobium leguminosarum bv . trifolii , Rl ArDHT (EC 4.2.1.25), that produce the corresponding 2-keto-3-deoxy-Sugar Acids. There is only a very limited amount of characterization data available on pentonate dehydratases, even though the enzymes from these oxidative pathways have potential applications with plant biomass pentose Sugars. The two bacterial enzymes share 41 % amino acid sequence identity and were expressed and purified from Escherichia coli as homotetrameric proteins. Both dehydratases were shown to accept pentonate and hexonate Sugar Acids as their substrates and require Mg^2+ for their activity. Cc XyDHT displayed the highest activity on D-xylonate and D-gluconate, while Rl ArDHT functioned best on D-fuconate, L-arabonate and D-galactonate. The configuration of the OH groups at C2 and C3 position of the Sugar acid were shown to be critical, and the C4 configuration also contributed substantially to the substrate recognition. The two enzymes were also shown to contain an iron–sulphur [Fe–S] cluster. Our phylogenetic analysis and mutagenesis studies demonstrated that the three conserved cysteine residues in the aldonic acid dehydratase group of IlvD/EDD family members, those of C60, C128 and C201 in Cc XyDHT, and of C59, C127 and C200 in Rl ArDHT, are needed for coordination of the [Fe–S] cluster. The iron–sulphur cluster was shown to be crucial for the catalytic activity (k_cat) but not for the substrate binding (K_m) of the two pentonate dehydratases.
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Characterization and mutagenesis of two novel iron-sulphur cluster pentonate dehydratases
Applied Microbiology and Biotechnology, 2016Co-Authors: Martina Andberg, Mervi Toivari, Merja Penttilä, Niina Aro-karkkainen, Paul Carlson, Merja Oja, Sophie Bozonnet, Nina Hakulinen, Michael O'donohue, Anu KoivulaAbstract:We describe here the identification and characterization of two novel enzymes belonging to the IlvD/EDD protein family, the D-xylonate dehydratase from Caulobacter crescentus, Cc XyDHT, (EC 4.2.1.82), and the L-arabonate dehydratase from Rhizobium leguminosarum bv. trifolii, Rl ArDHT (EC 4.2.1.25), that produce the corresponding 2-keto-3-deoxy-Sugar Acids. There is only a very limited amount of characterization data available on pentonate dehydratases, even though the enzymes from these oxidative pathways have potential applications with plant biomass pentose Sugars. The two bacterial enzymes share 41 % amino acid sequence identity and were expressed and purified from Escherichia coli as homotetrameric proteins. Both dehydratases were shown to accept pentonate and hexonate Sugar Acids as their substrates and require Mg2+ for their activity. Cc XyDHT displayed the highest activity on D-xylonate and D-gluconate, while Rl ArDHT functioned best on D-fuconate, L-arabonate and D-galactonate. The configuration of the OH groups at C2 and C3 position of the Sugar acid were shown to be critical, and the C4 configuration also contributed substantially to the substrate recognition. The two enzymes were also shown to contain an iron-sulphur [Fe-S] cluster. Our phylogenetic analysis and mutagenesis studies demonstrated that the three conserved cysteine residues in the aldonic acid dehydratase group of IlvD/EDD family members, those of C60, C128 and C201 in Cc XyDHT, and of C59, C127 and C200 in Rl ArDHT, are needed for coordination of the [Fe-S] cluster. The iron-sulphur cluster was shown to be crucial for the catalytic activity (k(cat)) but not for the substrate binding (K-m) of the two pentonate dehydratases.
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Production and applications of carbohydrate-derived Sugar Acids as generic biobased chemicals.
Critical Reviews in Biotechnology, 2015Co-Authors: Tuomas Mehtiö, Mervi Toivari, Merja Penttilä, Marilyn G. Wiebe, Ali Harlin, Anu KoivulaAbstract:AbstractThis review considers the chemical and biotechnological synthesis of Acids that are obtained by direct oxidation of mono- or oligosaccharide, referred to as Sugar Acids. It focuses on Sugar Acids which can be readily derived from plant biomass sources and their current and future applications. The three main classes of Sugar Acids are aldonic, aldaric and uronic Acids. Interest in organic Acids derived from Sugars has recently increased, as part of the interest to develop biorefineries which produce not only biofuels, but also chemicals to replace those currently derived from petroleum. More than half of the most desirable biologically produced platform chemicals are organic Acids. Currently, the only Sugar acid with high commercial production is d-gluconic acid. However, other Sugar Acids such as d-glucaric and meso-galactaric Acids are being produced at a lower scale. The Sugar Acids have application as sequestering agents and binders, corrosion inhibitors, biodegradable chelators for pharmaceut...
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Production and applications of carbohydrate-derived Sugar Acids as generic biobased chemicals.
Critical reviews in biotechnology, 2015Co-Authors: Tuomas Mehtiö, Mervi Toivari, Merja Penttilä, Marilyn G. Wiebe, Ali Harlin, Anu KoivulaAbstract:This review considers the chemical and biotechnological synthesis of Acids that are obtained by direct oxidation of mono- or oligosaccharide, referred to as Sugar Acids. It focuses on Sugar Acids w...
Cynthia Asiyo - One of the best experts on this subject based on the ideXlab platform.
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Gas chromatography–mass spectrometry resolution of Sugar acid enantiomers on a permethylated β-cyclodextrin stationary phase
Journal of Chromatography A, 2009Co-Authors: George Cooper, Minakshi Sant, Cynthia AsiyoAbstract:Analysis of compounds in meteorites revealed a need to simultaneously characterize multiple enantiomers of Sugar Acids (aldonic Acids) present in trace amounts. Analyses by gas chromatography-mass spectrometry demonstrated that all but two of the three-carbon through six-carbon straight-chained Sugar acid enantiomer pairs could be resolved using a single derivatization procedure and one set of GC parameters. Compounds were analyzed as their ethyl ester/O-triflouroacetyl, isopropyl ester/O-triflouroacetyl and isopropyl ester/O-pentafluoropropionyl derivatives on a capillary column containing permethylated β-cyclodextrin (Chirasil-Dex CB) as the stationary phase. Characteristic mass fragments are related to the ester groups while several ions are also common to derivatized monosaccharides.
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Gas chromatography–mass spectrometry resolution of Sugar acid enantiomers on a permethylated β-cyclodextrin stationary phase
Journal of chromatography. A, 2009Co-Authors: George Cooper, Minakshi Sant, Cynthia AsiyoAbstract:Analysis of compounds in meteorites revealed a need to simultaneously characterize multiple enantiomers of Sugar Acids (aldonic Acids) present in trace amounts. Analyses by gas chromatography-mass spectrometry demonstrated that all but two of the three-carbon through six-carbon straight-chained Sugar acid enantiomer pairs could be resolved using a single derivatization procedure and one set of GC parameters. Compounds were analyzed as their ethyl ester/O-triflouroacetyl, isopropyl ester/O-triflouroacetyl and isopropyl ester/O-pentafluoropropionyl derivatives on a capillary column containing permethylated beta-cyclodextrin (Chirasil-Dex CB) as the stationary phase. Characteristic mass fragments are related to the ester groups while several ions are also common to derivatized monosaccharides.
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Enantiomeric and Isotopic Analysis of Sugar Derivatives in Carbonaceous Meteorites
2002Co-Authors: George Cooper, Cynthia Asiyo, Kendra Turk, Donald L. DevincenziAbstract:Several classes of organic compounds are found in carbonaceous meteorites including amino Acids, carboxylic Acids, hydroxy Acids, purines, and pyrimidines. Such compounds are thought to have been delivered to the early Earth in asteroids and comets and may have played a role in the origin of life. Likewise, Sugar derivatives are critical to all known lifeforms. Recent analyses of the Murchison and Murray carbonaceous meteorites revealed a diverse suite of such derivatives, i.e., Sugar alcohols, and Sugar Acids. This presentation will focus primarily on the analysis of individual Sugar Acids - their enantiomeric and isotopic composition. Analysis of these compounds may reveal the nature of past (or present) meteoritic Sugars themselves. For example, if parent Sugars decomposed (by well-known mechanisms) to give the present Acids, were their enantiomeric ratios preserved? Combined with other evidence, the enantiomeric composition of such compounds as glyceric acid and (especially) rare Acids may help to answer such questions. C-13 and D isotope analysis of meteoritic Sugar alcohols (glycerol, threitol, ribitol, etc.) as a group revealed that they were indigenous to the meteorite. Preliminary C-13 analysis of glyceric acid shows that it is also extraterrestrial.
Innocenzo G. Casella - One of the best experts on this subject based on the ideXlab platform.
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Oxidation of Sugar Acids on polycrystalline platinum and gold electrodes modified with adsorbed bismuth oxide adlayers
Journal of Electroanalytical Chemistry, 2003Co-Authors: Innocenzo G. Casella, Maria Gatta, Michela ContursiAbstract:Abstract Cyclic voltammetry and chronoamperometry have been employed for the preparation and characterization of noble metal electrode substrates modified with bismuth adlayers. The influence of bismuth ad-atoms on the electrocatalytic activity of the resulting platinum and gold modified electrode was investigated toward the electrooxidation of several Sugar acid molecules in moderately alkaline medium. A direct comparative study regarding the catalytic activity between platinum and gold electrodes has been carried out in order to obtain useful information on the electrooxidation mechanism of Sugar Acids. It is found that different pre-adsorption processes of analyte on the platinum and gold electrodes were involved giving rise to different adsorption states in the oxide region and double region of potentials, respectively. The bismuth adsorbed species acts as a true catalyst on the direct electrooxidation pathway, providing the oxygen necessary for the oxidation of organic molecules adsorbed on the PtO x or Au sites in the oxide and double region, respectively.
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Study of Sugar Acids separation by high-performance anion-exchange chromatography–pulsed amperometric detection using alkaline eluents spiked with Ba2+, Sr2+, or Ca2+ as acetate or nitrate salts
Journal of Chromatography A, 1999Co-Authors: Tommaso R.i Cataldi, Cristiana Campa, Innocenzo G. CasellaAbstract:The influence of Ba2+, Ca2+ and Sr2+ ions on the anion-exchange chromatographic separation of some carboxylated Sugar Acids such as D-gluconic acid, N-acetylneuraminic acid, muramic acid and D-galacturonic, D-mannuronic and D-glucuronic Acids was investigated. The chromatographic technique was coupled with pulsed amperometric detection using gold ar a working electrode. Since acidic carbohydrates are strongly retained on the anion-exchange column, acetate and nitrate as counterions were used to regulate retention within 30 min. The addition of alkaline-earth metal ions at a millimolar concentration to the alkaline eluents does impart a noticeable decrease in the retention, especially for N-acetylneuraminic and uronic Acids. Complexation of these compounds with free divalent metal ions presumably occurs in the alkaline eluent. The extent of decreased retention is related to each divalent metal ion, and a good correlation was found between the retention modulus (eta = k'/k(o)') and the stability constant of each Sugar-metal ion complex. As expected, calcium ion induced a slightly greater retention compared to strontium and barium ions, and this is consistent with the fact that alduronate-calcium complexes are relatively more stable (eta < 1.00). We demonstrate also that upon the addition of Ba2+ and Sr2+ ions in the alkaline eluent, but the same cannot be claimed for calcium-containing eluents, there is a gain in sensitivity for all compounds investigated. The increment on the peak height when the column was eluted with NaOH spiked with Ba(NO3)(2) was generally higher (5-75%) than that with Ba(OAc)(2)
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Study of Sugar Acids separation by high-performance anion-exchange chromatography–pulsed amperometric detection using alkaline eluents spiked with Ba2+, Sr2+, or Ca2+ as acetate or nitrate salts
Journal of Chromatography A, 1999Co-Authors: Tommaso R.i Cataldi, Cristiana Campa, Innocenzo G. CasellaAbstract:Abstract The influence of Ba2+, Ca2+ and Sr2+ ions on the anion-exchange chromatographic separation of some carboxylated Sugar Acids such as d -gluconic acid, N-acetylneuraminic acid, muramic acid and d -galacturonic, d -mannuronic and d -glucuronic Acids was investigated. The chromatographic technique was coupled with pulsed amperometric detection using gold as a working electrode. Since acidic carbohydrates are strongly retained on the anion-exchange column, acetate and nitrate as counterions were used to regulate retention within 30 min. The addition of alkaline-earth metal ions at a millimolar concentration to the alkaline eluents does impart a noticeable decrease in the retention, especially for N-acetylneuraminic and uronic Acids. Complexation of these compounds with free divalent metal ions presumably occurs in the alkaline eluent. The extent of decreased retention is related to each divalent metal ion, and a good correlation was found between the retention modulus (η=k′/ko′) and the stability constant of each Sugar–metal ion complex. As expected, calcium ion induced a slightly greater retention compared to strontium and barium ions, and this is consistent with the fact that alduronate–calcium complexes are relatively more stable (η
Merja Penttilä - One of the best experts on this subject based on the ideXlab platform.
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Yeast as a tool to express Sugar acid transporters with biotechnological interest
Fems Yeast Research, 2017Co-Authors: David Ribas, Joana Sá-pessoa, Isabel Soares-silva, Sandra Paiva, Yvonne Nygård, Merja Penttilä, Laura Ruohonen, Margarida CasalAbstract:Sugar Acids can be used as platform chemicals to generate primary building blocks of industrially relevant products. Microbial production of these organic compounds at high yields requires the engineering of the enzymatic machinery and the presence of plasma membrane transporters able to export them outside the cells. In this study, several yeast carboxylic acid transporters belonging to the Jen family were screened for the transport of biotechnologically relevant Sugar Acids, namely gluconic, saccharic, mucic, xylaric and xylonic acid, and functionally characterised in Saccharomyces cerevisiae. We show that Jen permeases are capable of transporting most of these Sugar Acids, although with different specificities. Saccharate is a substrate of the transporters ScJen1-S271Q and KlJen2, gluconate of CaJen2 and KlJen2, and xylarate and mucate of CaJen2. A molecular docking approach of these transporters identified the residues that play a major role in the substrate binding of these Sugar Acids, namely R188 (ScJen1), R122 (CaJen2) and R127 (KlJen2), all equivalent residues (TMS II). The identification of Jen members as Sugar acid transporters can contribute to engineering efficient microbial cell factories with increased Sugar acid production, as the ScJen1 is able to promote substrate efflux.
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Characterization and mutagenesis of two novel iron–sulphur cluster pentonate dehydratases
Applied Microbiology and Biotechnology, 2016Co-Authors: Martina Andberg, Mervi Toivari, Merja Penttilä, Niina Aro-karkkainen, Paul Carlson, Merja Oja, Sophie Bozonnet, Nina Hakulinen, Michael O’donohue, Anu KoivulaAbstract:We describe here the identification and characterization of two novel enzymes belonging to the IlvD/EDD protein family, the D-xylonate dehydratase from Caulobacter crescentus , Cc XyDHT, (EC 4.2.1.82), and the L-arabonate dehydratase from Rhizobium leguminosarum bv . trifolii , Rl ArDHT (EC 4.2.1.25), that produce the corresponding 2-keto-3-deoxy-Sugar Acids. There is only a very limited amount of characterization data available on pentonate dehydratases, even though the enzymes from these oxidative pathways have potential applications with plant biomass pentose Sugars. The two bacterial enzymes share 41 % amino acid sequence identity and were expressed and purified from Escherichia coli as homotetrameric proteins. Both dehydratases were shown to accept pentonate and hexonate Sugar Acids as their substrates and require Mg^2+ for their activity. Cc XyDHT displayed the highest activity on D-xylonate and D-gluconate, while Rl ArDHT functioned best on D-fuconate, L-arabonate and D-galactonate. The configuration of the OH groups at C2 and C3 position of the Sugar acid were shown to be critical, and the C4 configuration also contributed substantially to the substrate recognition. The two enzymes were also shown to contain an iron–sulphur [Fe–S] cluster. Our phylogenetic analysis and mutagenesis studies demonstrated that the three conserved cysteine residues in the aldonic acid dehydratase group of IlvD/EDD family members, those of C60, C128 and C201 in Cc XyDHT, and of C59, C127 and C200 in Rl ArDHT, are needed for coordination of the [Fe–S] cluster. The iron–sulphur cluster was shown to be crucial for the catalytic activity (k_cat) but not for the substrate binding (K_m) of the two pentonate dehydratases.
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Characterization and mutagenesis of two novel iron-sulphur cluster pentonate dehydratases
Applied Microbiology and Biotechnology, 2016Co-Authors: Martina Andberg, Mervi Toivari, Merja Penttilä, Niina Aro-karkkainen, Paul Carlson, Merja Oja, Sophie Bozonnet, Nina Hakulinen, Michael O'donohue, Anu KoivulaAbstract:We describe here the identification and characterization of two novel enzymes belonging to the IlvD/EDD protein family, the D-xylonate dehydratase from Caulobacter crescentus, Cc XyDHT, (EC 4.2.1.82), and the L-arabonate dehydratase from Rhizobium leguminosarum bv. trifolii, Rl ArDHT (EC 4.2.1.25), that produce the corresponding 2-keto-3-deoxy-Sugar Acids. There is only a very limited amount of characterization data available on pentonate dehydratases, even though the enzymes from these oxidative pathways have potential applications with plant biomass pentose Sugars. The two bacterial enzymes share 41 % amino acid sequence identity and were expressed and purified from Escherichia coli as homotetrameric proteins. Both dehydratases were shown to accept pentonate and hexonate Sugar Acids as their substrates and require Mg2+ for their activity. Cc XyDHT displayed the highest activity on D-xylonate and D-gluconate, while Rl ArDHT functioned best on D-fuconate, L-arabonate and D-galactonate. The configuration of the OH groups at C2 and C3 position of the Sugar acid were shown to be critical, and the C4 configuration also contributed substantially to the substrate recognition. The two enzymes were also shown to contain an iron-sulphur [Fe-S] cluster. Our phylogenetic analysis and mutagenesis studies demonstrated that the three conserved cysteine residues in the aldonic acid dehydratase group of IlvD/EDD family members, those of C60, C128 and C201 in Cc XyDHT, and of C59, C127 and C200 in Rl ArDHT, are needed for coordination of the [Fe-S] cluster. The iron-sulphur cluster was shown to be crucial for the catalytic activity (k(cat)) but not for the substrate binding (K-m) of the two pentonate dehydratases.
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Production and applications of carbohydrate-derived Sugar Acids as generic biobased chemicals.
Critical Reviews in Biotechnology, 2015Co-Authors: Tuomas Mehtiö, Mervi Toivari, Merja Penttilä, Marilyn G. Wiebe, Ali Harlin, Anu KoivulaAbstract:AbstractThis review considers the chemical and biotechnological synthesis of Acids that are obtained by direct oxidation of mono- or oligosaccharide, referred to as Sugar Acids. It focuses on Sugar Acids which can be readily derived from plant biomass sources and their current and future applications. The three main classes of Sugar Acids are aldonic, aldaric and uronic Acids. Interest in organic Acids derived from Sugars has recently increased, as part of the interest to develop biorefineries which produce not only biofuels, but also chemicals to replace those currently derived from petroleum. More than half of the most desirable biologically produced platform chemicals are organic Acids. Currently, the only Sugar acid with high commercial production is d-gluconic acid. However, other Sugar Acids such as d-glucaric and meso-galactaric Acids are being produced at a lower scale. The Sugar Acids have application as sequestering agents and binders, corrosion inhibitors, biodegradable chelators for pharmaceut...
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Production and applications of carbohydrate-derived Sugar Acids as generic biobased chemicals.
Critical reviews in biotechnology, 2015Co-Authors: Tuomas Mehtiö, Mervi Toivari, Merja Penttilä, Marilyn G. Wiebe, Ali Harlin, Anu KoivulaAbstract:This review considers the chemical and biotechnological synthesis of Acids that are obtained by direct oxidation of mono- or oligosaccharide, referred to as Sugar Acids. It focuses on Sugar Acids w...
