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Literature summary for 1.6.5.4 extracted from

  • Drew, D.P.; Lunde, C.; Lahnstein, J.; Fincher, G.B.
    Heterologous expression of cDNAs encoding monodehydroascorbate reductases from the moss, Physcomitrella patens and characterization of the expressed enzymes (2007), Planta, 225, 945-954.
    View publication on PubMed
Search for more literature for 1.6.5.4

Activating Compound

Activating Compound Comment Organism Structure
NADH NADH is the preferred electron donor Physcomitrium patens
NADPH NADH is the preferred electron donor Physcomitrium patens

Cloned(Commentary)

Cloned (Comment) Organism
expression in Escherichia coli Physcomitrium patens

Protein Variants

Protein Variants Comment Organism
C69A mutation has a negligible effect on enzyme activity under standard reaction conditions. The C69A mutant is more resistant to the inhibitory effects of beta-chloromercuribenzoate than the wild type PpMDHAR2 protein Physcomitrium patens

Inhibitors

Inhibitors Comment Organism Structure
beta-chloromercuribenzoate PpMDHAR1 is almost completely inactivated after a 20 min preincubation with 0.25 mM beta-chloromercuribenzoate. At 0.05 mM the enzyme retains 11% of the initial activity. Physcomitrium patens
chloromercuribenzoate at 0.05 mM PpMDHAR3 retains 80% of the initial activity; PpMDHAR2 is almost completely inactivated after a 20 min preincubation with 0.25 mM chloromercuribenzoate. At 0.05 mM the enzyme retains 14% of the initial activity. The C69A mutant is more resistant to the inhibitory effects of chloromercuribenzoate than the wild type PpMDHAR2 protein Physcomitrium patens

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.0078
-
 NADH
-
 Physcomitrium patens
0.0096
-
 NADH
-
 Physcomitrium patens
0.0178
-
 NADH
-
 Physcomitrium patens
0.088
-
 NADPH
-
 Physcomitrium patens
0.223
-
 NADPH
-
 Physcomitrium patens
0.99
-
 NADPH
-
 Physcomitrium patens

Organism

Organism UniProt Comment Textmining
Physcomitrium patens Q2I826
-
-
Physcomitrium patens Q2I827
-
-
Physcomitrium patens Q2I828
-
-

Reaction

Reaction Comment Organism Reaction ID
NADH + H+ + 2 monodehydroascorbate = NAD+ + 2 ascorbate PpMDHARs follow a ping-pong kinetic mechanism Physcomitrium patens
a

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
152
-
-
 Physcomitrium patens
164
-
-
 Physcomitrium patens

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
NADH + monodehydroascorbate
-
 Physcomitrium patens NAD+ + ascorbate
-
 ?
NADPH + monodehydroascorbate NADH is the preferred electron donor Physcomitrium patens NADP+ + ascorbate
-
 ?

Synonyms

Synonyms Comment Organism
MDHAR1
-
 Physcomitrium patens
MDHAR2
-
 Physcomitrium patens
MDHAR3
-
 Physcomitrium patens
monodehydroascorbate reductase
-
 Physcomitrium patens
PpMDHAR1
-
 Physcomitrium patens
PpMDHAR2
-
 Physcomitrium patens
PpMDHAR3
-
 Physcomitrium patens

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
119
-
 NADH
-
 Physcomitrium patens
128
-
 NADH
-
 Physcomitrium patens
170
-
 NADH
-
 Physcomitrium patens

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
8.1
-
-
 Physcomitrium patens

pH Range

pH Minimum pH Maximum Comment Organism
7.6 8.7 85% or greater activity between pH 7.6 and pH 8.7 Physcomitrium patens

Cofactor

Cofactor Comment Organism Structure
FAD contains a single non-covalently bound FAD coenzyme molecule Physcomitrium patens
NADH NADH is the preferred electron donor Physcomitrium patens
NADPH NADH is the preferred electron donor Physcomitrium patens