A Novel Enzymatic Approach to the Massproduction of L-Galactose from L-Sorbose

LEANG, KHIM; Maekawa, Kanako; Menavuvu, Buetusiwa Thomas; Morimoto, Kenji; Granström, Tom; Takada, Goro; Izumori, Ken

doi:10.1263/jbb.97.383

Cited by 8 publications

(9 citation statements)

References 31 publications

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“…4, conversion of D-Glc to L-ascorbic acid through the Smirnoff-Wheeler pathway takes a remarkable 10 steps, 8 of which are required simply to convert D-Glc to L-Gal. L-Gal, representing the epimerization product of D-Gal at four carbon atoms, is rarely found in nature (29), emphasizing the importance of this portion of the pathway. Because two of the interconverted substrates and products of GME, namely GDP-D-Man and GDP-L-Gal, are utilized in biosynthesis of cell wall polysaccharides (30, 31) and/or protein glycosylation (32), the values were obtained by fitting the experimental data to the MichaelisMenten equation using the K m calculator of the BioMechanic program.…”

Section: Discussionmentioning

confidence: 99%

Arabidopsis VTC2 Encodes a GDP-l-Galactose Phosphorylase, the Last Unknown Enzyme in the Smirnoff-Wheeler Pathway to Ascorbic Acid in Plants

Linster¹,

Gomez²,

Christensen³

et al. 2007

Journal of Biological Chemistry

171

176

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The first committed step in the biosynthesis of L-ascorbate from D-glucose in plants requires conversion of GDP-L-galactose to L-galactose 1-phosphate by a previously unidentified enzyme. Here we show that the protein encoded by VTC2, a gene mutated in vitamin C-deficient Arabidopsis thaliana strains, is a member of the GalT/Apa1 branch of the histidine triad protein superfamily that catalyzes the conversion of GDP-L-galactose to L-galactose 1-phosphate in a reaction that consumes inorganic phosphate and produces GDP. In characterizing recombinant VTC2 from A. thaliana as a specific GDP-L-galactose/GDP-Dglucose phosphorylase, we conclude that enzymes catalyzing each of the ten steps of the Smirnoff-Wheeler pathway from glucose to ascorbate have been identified. Finally, we identify VTC2 homologs in plants, invertebrates, and vertebrates, suggesting that a similar reaction is used widely in nature.Vitamin C (L-ascorbic acid) is well known as an important antioxidant and enzyme cofactor in animals (1, 2) and in plants (3). Apparently, all plants are able to produce vitamin C and mutants completely deficient in synthesis have not been described, suggesting an essential role of ascorbate biosynthesis in these organisms (4). Although vertebrate vitamin C synthesis is restricted to one organ (liver in mammals and kidney in fish, amphibians, and reptiles) (5, 6), virtually all cells in plants can form ascorbate (4). In the few vertebrate species, such as humans, which lack ascorbate biosynthesis, loss of the pathway is compensated by dietary intake, particularly from plants.Different pathways of ascorbate synthesis have evolved in animals and plants. In animals, ascorbate is formed from UDP-D-glucuronate in a pathway involving D-glucuronate formation, reduction and lactonization of D-glucuronate to L-gulonolactone and oxidation of the latter to L-ascorbate (reviewed in Ref. 7). Deficiency of the enzyme catalyzing this last step (L-gulonolactone oxidase) is responsible for the loss of ascorbate synthesis in the vitamin C-requiring vertebrates (8). In plants, the ascorbate synthesis pathway has remained elusive until recently and alternative pathways may exist (9). The Smirnoff-Wheeler pathway (10) has garnered strong biochemical and genetic support (11-16) and appears to represent the major route to ascorbate biosynthesis. In this pathway, GDP-D-mannose, formed from D-mannose 1-phosphate, is successively converted to GDP-L-galactose, L-galactose 1-phosphate, L-galactose, L-galactono-1,4-lactone, and finally to L-ascorbate.Screens for ozone-sensitive (17) or ascorbate-deficient (18) mutants in Arabidopsis thaliana led to the identification of four loci (VTC1, VTC2, VTC3, and VTC4) involved in the maintenance of the vitamin C pool. Characterization of the vtc1 (19) and vtc4 (15) mutants, as well as biochemical studies (14), have allowed the identification of two of the enzymes required for L-ascorbic acid synthesis through the Smirnoff-Wheeler pathway. VTC1 and VTC4 encode GDP-mannose pyrophosphorylase (19) and L-Gal-1-P ...

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Section: Discussionmentioning

confidence: 99%

Arabidopsis VTC2 Encodes a GDP-l-Galactose Phosphorylase, the Last Unknown Enzyme in the Smirnoff-Wheeler Pathway to Ascorbic Acid in Plants

Linster¹,

Gomez²,

Christensen³

et al. 2007

Journal of Biological Chemistry

171

176

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“…The CF-PcDTE supernatant was then collected by centrifugation at 10,000 × g over 10 min at 4°C and then partially purified by the addition of polyethylene glycol #6000 (PEG#6000, final concentration 30% w/v). The resulting precipitate was dissolved in the same buffer and immobilized on Chitopearl beads BCW 2510 (Fuji Spinning, Tokyo) at 4°C by a modified version of a previously reported method, 34) providing IE-PcDTE.…”

Section: Methodsmentioning

confidence: 99%

Enzymatic production of three 6-deoxy-aldohexoses from l-rhamnose

Shompoosang

Yoshihara

Uechi

et al. 2014

Bioscience, Biotechnology, and Biochemistry

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6-Deoxy-l-glucose, 6-deoxy-l-altrose, and 6-deoxy-l-allose were produced from l-rhamnose with an immobilized enzyme that was partially purified (IE) and an immobilized Escherichia coli recombinant treated with toluene (TT). 6-Deoxy-l-psicose was produced from l-rhamnose by a combination of l-rhamnose isomerase (TT-PsLRhI) and d-tagatose 3-epimerase (TT-PcDTE). The purified 6-deoxy-l-psicose was isomerized to 6-deoxy-l-altrose and 6-deoxy-l-allose with l-arabinose isomerase (TT-EaLAI) and l-ribose isomerase (TT-AcLRI), respectively, and then was epimerized to l-rhamnulose with immobilized d-tagatose 3-epimerase (IE-PcDTE). Following purification, l-rhamnulose was converted to 6-deoxy-l-glucose with d-arabinose isomerase (TT-BpDAI). The equilibrium ratios of 6-deoxy-l-psicose:6-deoxy-l-altrose, 6-deoxy-l-psicose:6-deoxy-l-allose, and l-rhamnulose:6-deoxy-l-glucose were 60:40, 40:60, and 27:73, respectively. The production yields of 6-deoxy-l-glucose, 6-deoxy-l-altrose, and 6-deoxy-l-allose from l-rhamnose were 5.4, 14.6, and 25.1%, respectively. These results indicate that the aldose isomerases used in this study acted on 6-deoxy aldohexoses.

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“…Unfortunately, none of the reported isomerases shows a high activity toward L-hexoses. Still, some aldose isomerases have been used for Laldohexose production, including L-rhamnose isomerase (EC 5.3.1.14) (Bhuiyan et al 1997;Leang et al 2004a;Takata et al 2011), L-ribose isomerase (EC 5.3.1.B3) (Terami et al 2015), and D-arabinose isomerase (EC 5.3.1.3) (Leang et al 2003). Some aldose phosphate isomerases have also shown potential for the application of L-aldohexose production, including D-ribose-5-phosphate isomerase (EC 5.3.1.6) (Park et al 2010), D-glucose-6-phosphate isomerase (EC 5.3.1.9) ), D-mannose-6-phosphate isomerase (EC 5.3.1.8) , and D-galactose-6-phosphate isomerase (EC 5.3.1.26) (Park et al 2007).…”

Section: C-3 Epimerization Between L-ketohexosesmentioning

confidence: 99%

“…The enzyme immobilized on BCW 2510 beads produced approximately 7.5 g L −1 of L-galactose from 25 g L −1 of L-tagatose, with L-talose production as a minor byproduct during the reactions (Leang et al 2004a). …”

Section: Production Of L-galactose From L-tagatosementioning

confidence: 99%

Advances in the enzymatic production of l-hexoses

Chen

Zhang

et al. 2016

Appl Microbiol Biotechnol

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Rare sugars have recently drawn attention because of their potential applications and huge market demands in the food and pharmaceutical industries. All L-hexoses are considered rare sugars, as they rarely occur in nature and are thus very expensive. L-Hexoses are important components of biologically relevant compounds as well as being used as precursors for certain pharmaceutical drugs and thus play an important role in the pharmaceutical industry. Many general strategies have been established for the synthesis of L-hexoses; however, the only one used in the biotechnology industry is the Izumoring strategy. In hexose Izumoring, four entrances link the D- to L-enantiomers, ketose 3-epimerases catalyze the C-3 epimerization of L-ketohexoses, and aldose isomerases catalyze the specific bioconversion of L-ketohexoses and the corresponding L-aldohexoses. In this article, recent studies on the enzymatic production of various L-hexoses are reviewed based on the Izumoring strategy.

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A Novel Enzymatic Approach to the Massproduction of L-Galactose from L-Sorbose

Cited by 8 publications

References 31 publications

Arabidopsis VTC2 Encodes a GDP-l-Galactose Phosphorylase, the Last Unknown Enzyme in the Smirnoff-Wheeler Pathway to Ascorbic Acid in Plants

Arabidopsis VTC2 Encodes a GDP-l-Galactose Phosphorylase, the Last Unknown Enzyme in the Smirnoff-Wheeler Pathway to Ascorbic Acid in Plants

Enzymatic production of three 6-deoxy-aldohexoses from l-rhamnose

Advances in the enzymatic production of l-hexoses

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