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Literature summary extracted from

  • Linster, C.L.; Adler, L.N.; Webb, K.; Christensen, K.C.; Brenner, C.; Clarke, S.G.
    A second GDP-L-galactose phosphorylase in Arabidopsis en route to vitamin C. Covalent intermediate and substrate requirements for the conserved reaction (2008), J. Biol. Chem., 283, 18483-18492.
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

EC Number Cloned (Comment) Organism
2.7.7.69
-
 Arabidopsis thaliana

Protein Variants

EC Number Protein Variants Comment Organism
2.7.7.69 G224D less than 0.1% of wild-type activity Arabidopsis thaliana
2.7.7.69 H238N less than 0.1% of wild-type activity Arabidopsis thaliana
2.7.7.69 S290F less than 0.1% of wild-type activity Arabidopsis thaliana

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
2.7.7.69 0.0044
-
 GDP-alpha-D-glucose pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 0.0079
-
 GDP-alpha-L-galactose pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 0.0083
-
 GDP-alpha-L-galactose pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 0.012
-
 GDP-alpha-D-glucose pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 0.22
-
 phosphate presence of GDP-G-glucose, pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 0.52
-
 GDP-alpha-D-mannose pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 0.76
-
 phosphate presence of GDP-alpha-D-glucose, pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 1
-
 phosphate presence of GDP-L-galactose, pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 1.3
-
 GDP-alpha-D-mannose pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 2.4
-
 phosphate presence of GDP-alpha-L-galactose, pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 6
-
 alpha-L-galactose 1-phosphate pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 10
-
 alpha-D-glucose 1-phosphate pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 16
-
 alpha-D-galactose 1-phosphate pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 29
-
 alpha-D-glucose 1-phosphate pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 45
-
 alpha-D-galactose 1-phosphate pH 7.5, 26°C Arabidopsis thaliana

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
2.7.7.69 GDP-beta-L-galactose + phosphate Arabidopsis thaliana enzyme guanylylates a conserved active site His residue with GDP-L-galactose, forming L-galactose 1-phosphate for vitamin C synthesis, and regeneration of the enzyme with phosphate to form GDP GDP + beta-L-galactose 1-phosphate
-
 r

Organism

EC Number Organism UniProt Comment Textmining
2.7.7.69 Arabidopsis thaliana Q8RWE8 isoform Vtc2
-
2.7.7.69 Arabidopsis thaliana Q9FLP9 isoform Vtc5
-

Specific Activity [micromol/min/mg]

EC Number Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
2.7.7.69 14.2
-
 pH 7.5, 26°C, substrate GDP-alpha-D-glucose Arabidopsis thaliana
2.7.7.69 15.1
-
 pH 7.5, 26°C, substrate GDP-alpha-L-galactose Arabidopsis thaliana

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2.7.7.69 alpha-D-glucose 1-phosphate + GDP
-
 Arabidopsis thaliana GDP-alpha-D-glucose + phosphate
-
 r
2.7.7.69 alpha-D-mannose 1-phosphate + GDP
-
 Arabidopsis thaliana GDP-alpha-D-mannose + phosphate
-
 r
2.7.7.69 alpha-L-galactose 1-phosphate + GDP
-
 Arabidopsis thaliana GDP-alpha-L-galactose + phosphate
-
 r
2.7.7.69 GDP-alpha-D-galactose + phosphate
-
 Arabidopsis thaliana GDP + alpha-D-galactose 1-phosphate
-
 r
2.7.7.69 GDP-alpha-D-glucose + phosphate
-
 Arabidopsis thaliana alpha-D-glucose 1-phosphate + GDP
-
 r
2.7.7.69 GDP-alpha-D-mannose + phosphate
-
 Arabidopsis thaliana alpha-D-mannose 1-phosphate + GDP
-
 r
2.7.7.69 GDP-beta-L-galactose + phosphate enzyme guanylylates a conserved active site His residue with GDP-L-galactose, forming L-galactose 1-phosphate for vitamin C synthesis, and regeneration of the enzyme with phosphate to form GDP Arabidopsis thaliana GDP + beta-L-galactose 1-phosphate
-
 r
2.7.7.69 GDP-beta-L-galactose + phosphate reaction proceeds through a covalent guanylated histidine residue within the histidine triad motif Arabidopsis thaliana GDP + beta-L-galactose 1-phosphate
-
 r
2.7.7.69 additional information poor reactivity of hexose 1-phosphates as acceptors Arabidopsis thaliana ?
-
 ?

Synonyms

EC Number Synonyms Comment Organism
2.7.7.69 Vtc5
-
 Arabidopsis thaliana

Turnover Number [1/s]

EC Number Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
2.7.7.69 0.024
-
 GDP-alpha-D-mannose pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 0.093
-
 GDP-alpha-D-mannose pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 3.8
-
 alpha-D-galactose 1-phosphate pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 5.8
-
 alpha-D-glucose 1-phosphate pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 6
-
 alpha-D-galactose 1-phosphate pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 6
-
 alpha-L-galactose 1-phosphate pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 9.9
-
 GDP-alpha-D-glucose pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 12
-
 alpha-D-glucose 1-phosphate pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 13
-
 GDP-alpha-L-galactose pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 23
-
 GDP-alpha-D-glucose pH 7.5, 26°C Arabidopsis thaliana
2.7.7.69 27
-
 GDP-alpha-L-galactose pH 7.5, 26°C Arabidopsis thaliana