1.3.2.3: L-galactonolactone dehydrogenase
This is an abbreviated version!
For detailed information about L-galactonolactone dehydrogenase, go to the full flat file.
Word Map on EC 1.3.2.3
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1.3.2.3
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asa
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l-galactose
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dehydroascorbate
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monodehydroascorbate
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l-galactose-1-phosphate
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l-gulono-1,4-lactone
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galdh
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gdp-d-mannose
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mdhar
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gdp-l-galactose
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aldonolactone
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d-galacturonate
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ascorbate-glutathione
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smirnoff-wheeler
- 1.3.2.3
- asa
- l-galactose
- dehydroascorbate
- monodehydroascorbate
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l-galactose-1-phosphate
- l-gulono-1,4-lactone
- galdh
- gdp-d-mannose
- mdhar
- gdp-l-galactose
- aldonolactone
- d-galacturonate
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ascorbate-glutathione
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smirnoff-wheeler
Reaction
+ = + 2 ferrocytochrome c + 2 H+
Synonyms
dehydrogenase, galactonolactone, ferricytochrome c oxidoreductase, galactono-1,4-lactone dehydrogenase, galactonolactone dehydrogenase, GALDH, GalL dehydrogenase, GalLDH, GLDase, GLDH, GLDH-A1, GLDH-B1, GLDH-D1, GLDH1, GLDHase, L-galactone-1,4-lactone dehydrogenase, L-galactono-1, 4-lactone dehydrogenase, L-galactono-1,4-lactone dehydrogenase, L-galactono-gamma-lactone dehydrogenase, L-GalLDH, L-GalLDH1, L-GalLDH2, LsL-GalLDH, RrGalLDH
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General Information
General Information on EC 1.3.2.3 - L-galactonolactone dehydrogenase
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malfunction
metabolism
physiological function
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a change in ascorbic acid content caused by silencing or overexpressing GLDH, respectively, in rice plants leads to a changed plant growth and seed set
malfunction
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GLDH-suppressed transgenic rices, GI-1 and GI-2, which have constitutively low (between 30% and 50%) leaf ascorbic acid content compared with the wild-type plants, exhibit a significantly reduced tiller number
malfunction
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overexpression of L-galactono-gamma-lactone dehydrogenase increases vitamin C, total phenolics and antioxidant activity in lettuce through bio-fortification
malfunction
transgenic tobacco plants overexpressing GalLDH show an enhanced GalLDH transcript levels, GalLDH activities, and L-ascorbic acid accumulation as compared to wild-type plants. Abiotic stress tolerance is enhanced in transgenic plants compared to wild-type plants
malfunction
analysis of the vtc2-1 mutant shows that complex I assembly is not affected in this mutant, while it is affected in the mutant ndufs4 of NADH dehydrogenase [ubiquinone] iron-sulfur protein 4 of Arabidopsis thaliana Col-0, in ndufs4, complex I is not assembled and GLDH is not present in any intermediate larger than 450 kDa. This suggests that the 450 kDa intermediate is a precursor of complex I. Very low amounts of complex I and other assembly intermediates in the gldh mutant, suggesting that the assembly of complex I is not completely arrested, but it is severely impaired in the absence of GLDH
malfunction
ascorbic acid deficiency in L-GalLDH-suppressed transgenic rice, GI-1 and GI-2, which have constitutively low (between 30% and 50%) leaf and grain ascorbic acid content compared with the wild-type, leads to increased grain chalkiness in the transgenic rice. Deficiency of ascorbic acid also results in a higher lipid peroxidation and H2O2 content, accompanied by a lower hydroxyl radical scavenging rate, total antioxidant capacity and photosynthetic ability. Changes of the enzyme activities and gene transcript abundances related to starch synthesis are also observed in GI-1 and GI-2 grains. Phenotypes, detailed overview
malfunction
decreasing TaGLDH expression in wheat significantly reduces GLDH activity and ascorbic acid content, but in the leaf tissues undergoing TaGLDH silencing, the reductions of total and reduced ascorbic acid contents are considerably below the decreases in TaGLDH expression and GLDH activity. Association of the mutant TaGLDH-A1b variant with enhanced tolerance to water deficiency stress, overview
malfunction
homozygous Arabidopsis thaliana mutant gldhRNAi3-11 plants show approximately 40% of the GLDH activity of wild-type controls and are viable under standard laboratory conditions. Mutant gldhRNAi3-11 plants show about 20% decrease in the contents of reduced ascorbic acid and total ascorbic acid. Partial suppression of GLDH activity confers significant reduction in leaf water loss through decreasing stomatal aperture size in Arabidopsis thaliana, phenotype, overview
malfunction
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homozygous Arabidopsis thaliana mutant gldhRNAi3-11 plants show approximately 40% of the GLDH activity of wild-type controls and are viable under standard laboratory conditions. Mutant gldhRNAi3-11 plants show about 20% decrease in the contents of reduced ascorbic acid and total ascorbic acid. Partial suppression of GLDH activity confers significant reduction in leaf water loss through decreasing stomatal aperture size in Arabidopsis thaliana, phenotype, overview
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malfunction
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analysis of the vtc2-1 mutant shows that complex I assembly is not affected in this mutant, while it is affected in the mutant ndufs4 of NADH dehydrogenase [ubiquinone] iron-sulfur protein 4 of Arabidopsis thaliana Col-0, in ndufs4, complex I is not assembled and GLDH is not present in any intermediate larger than 450 kDa. This suggests that the 450 kDa intermediate is a precursor of complex I. Very low amounts of complex I and other assembly intermediates in the gldh mutant, suggesting that the assembly of complex I is not completely arrested, but it is severely impaired in the absence of GLDH
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GLDH catalyzes the last step of L-ascorbate, AsA, biosynthesis in plants, but the upstream genes in the AsA biosynthetic pathway are responsible for enhancing the AsA content in plants, regulation, overview
metabolism
L-galactono-1,4-lactone dehydrogenase is one of the enzymes of the Smirnoff-Wheeler's branch of ascorbic acid biosynthetic pathway, overview
metabolism
the enzyme catalyzes the last step of ascorbate synthesis by oxidising L-galactone-1,4-lactone to ascorbate and transferring two electrons to cytochrome c
metabolism
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the enzyme catalyzes the last step of ascorbate synthesis by oxidising L-galactone-1,4-lactone to ascorbate and transferring two electrons to cytochrome c
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GalLDH is a key modulation point of the physiology of pepper plants. GalLDH might have a pivotal role which allows the interaction with several neighboring respiratory oxidases. GalLDH is an unstable protein, and this contributes to maintain and even increase the ascorbate levels, it has also an important role during development and fruit ripening. Respiration can control ascorbate synthesis in plants and for its optimum biosynthesis is necessary an electron flux through the complex I of the mitochondrial electron transport chain. In vitro experiments on GalLDH activity in the presence of GSH show, the ascorbate levels in pepper fruits also depend on the redox chemical surrounding of the GalLDH, since this enzyme activity is inhibited by GSH
physiological function
in higher plants, L-galactono-1,4-lactone dehydrogenase (GLDH) plays important roles in ascorbic acid biosynthesis and assembly of respiration complex I. GLDH is essential for the final steps of biosynthesis of ascorbic acid, a vital and abundant antioxidant, through the D-mannose/L-galactose pathway. GLDH activities are required for the normal growth and development of plant cells and organs and their efficient response to adverse environmental factors. The enzyme is important for regulation of water stress via the ascorbic acid level in guard cells, because H2O2 accumulation in the guard cells is vital for stomata closing, and ascorbic acid, being the most abundant water-soluble antioxidant in plant cells, plays a critical role in regulating cellular level of H2O2
physiological function
L-galactono-1,4-lactone dehydrogenase catalyzes the ultimate step of ascorbic acid biosynthesis in higher plants. L-GalLDH is attached to complex I of the mitochondrial electron transport chain, which uses L-galactono-1,4-lactone as an electron donor to reduce cytochrome c between complexes III and IV, while l-GalLis converted into ascorbic acid. Role of L-GalLDH in the control of cell, organ, and plant growth
physiological function
L-galactono-1,4-lactone dehydrogenase catalyzes the ultimate step of ascorbic acid biosynthesis in higher plants. L-GalLDH is attached to complex I of the mitochondrial electron transport chain,which uses L-galactono-1,4-lactone as an electron donor to reduce cytochrome c between complexes III and IV, while l-GalLis converted into ascorbic acid. Role of L-GalLDH in the control of cell, organ, and plant growth
physiological function
the enzyme can play two distinct roles during complex I assembly. First, it can play a structural or stabilizing role for specific assembly intermediates. Second, it can indirectly be essential through providing the ascorbate that might be required during the assembly process. Enzyme GLDH is not required for the early stages of complex I assembly, but it is important for at least one step of the assembly process (transition from the 200 kDa intermediate to the 400 kDa intermediate), it is associated with some assembly intermediates, but it is absent from the mature complex
physiological function
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the chlorophyll fluorescence parameters are significantly higher in enzyme-overexpressing mutants than that in wild type after 14 day high light. The degradation of photosynthetic pigment in wild type is more severe than that in the mutant. GLDH-236OE accumulates more ascorbate, anthocyanins, flavonoids, and phenolics, while wild type accumulates more reactive oxygen species during high light
physiological function
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the enzyme can play two distinct roles during complex I assembly. First, it can play a structural or stabilizing role for specific assembly intermediates. Second, it can indirectly be essential through providing the ascorbate that might be required during the assembly process. Enzyme GLDH is not required for the early stages of complex I assembly, but it is important for at least one step of the assembly process (transition from the 200 kDa intermediate to the 400 kDa intermediate), it is associated with some assembly intermediates, but it is absent from the mature complex
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