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Literature summary for 1.6.5.4 extracted from

  • Li, F.; Wu, Q.Y.; Sun, Y.L.; Ma, N.N.; Wang, X.Y.; Meng, Q.W.
    Evidence that the amino acid residue Cys117 of chloroplastic monodehydroascorbate reductase is involved in its activity and structural stability (2010), Int. J. Biol. Macromol., 46, 350-355.
    View publication on PubMed
Search for more literature for 1.6.5.4

Cloned(Commentary)

Cloned (Comment) Organism
expressed as GST-tagged enzyme in Escherichia coli BL21 cells Solanum lycopersicum

Protein Variants

Protein Variants Comment Organism
C117A the binding affinity of NADH in the mutant MDAR is lower than that of wild type MDAR as indicated by about 1.5-3fold increase of the Km value for NADH, the mutant is less thermo-stable than the wild type enzyme Solanum lycopersicum
C117S the binding affinity of NADH in the mutant MDAR is lower than that of wild type MDAR as indicated by about 1.5-3fold increase of the Km value for NADH, the mutant is less thermo-stable than the wild type enzyme Solanum lycopersicum

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.00144
-
 monodehydroascorbate native wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
0.0015
-
 monodehydroascorbate recombinant wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
0.00151
-
 monodehydroascorbate mutant enzyme C117S, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
0.00155
-
 monodehydroascorbate mutant enzyme C117A, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
0.00621
-
 NADH recombinant wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
0.0063
-
 NADH native wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
0.00962
-
 NADH mutant enzyme C117S, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
0.01461
-
 NADH mutant enzyme C117A, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum

Localization

Localization Comment Organism GeneOntology No. Textmining
chloroplast
-
 Solanum lycopersicum 9507
-

Organism

Organism UniProt Comment Textmining
Solanum lycopersicum
-
-
-

Purification (Commentary)

Purification (Comment) Organism
glutathione Sepharose column chromatography Solanum lycopersicum

Renatured (Commentary)

Renatured (Comment) Organism
using 0.8 M guanidine-HCl at 25°C for 24 h Solanum lycopersicum

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
NADH + monodehydroascorbate
-
 Solanum lycopersicum NAD+ + ascorbate
-
 ?

Synonyms

Synonyms Comment Organism
MDAR
-
 Solanum lycopersicum

Temperature Stability [°C]

Temperature Stability Minimum [°C] Temperature Stability Maximum [°C] Comment Organism
35 62 the activity of wild type MDAR has no much change after heat treatment at temperatures below 35°C, steep decrease of activity is observed between 35 and 55°C, and a complete loss in activity occurs above 62°C. The midpoint of thermal inactivation of wild type MDAR is about 52.1°C Solanum lycopersicum

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
62.67
-
 NADH mutant enzyme C117A, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
89.89
-
 NADH mutant enzyme C117S, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
121.4
-
 NADH recombinant wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
126.6
-
 NADH native wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum

Cofactor

Cofactor Comment Organism Structure
NADH
-
 Solanum lycopersicum

General Information

General Information Comment Organism
physiological function MDARis a key enzyme in the ascorbate-glutathione cycle, MDAR is crucial for ascorbate regeneration and essential for maintaining the reduced pool of ascorbate Solanum lycopersicum

kcat/KM [mM/s]

kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
4290
-
 NADH mutant enzyme C117A, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
9360
-
 NADH mutant enzyme C117S, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
19270
-
 NADH recombinant wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum
20420
-
 NADH native wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C Solanum lycopersicum