Any feedback?
Please rate this page
(literature.php)
(0/150)

BRENDA support

Literature summary for 1.11.1.11 extracted from

  • Mandelman, D.; Jamal, J.; Poulos, T.L.
    Identification of two electron-transfer sites in ascorbate peroxidase using chemical modification, enzyme kinetics, and crystallography (1998), Biochemistry, 37, 17610-17617.
    View publication on PubMed

Crystallization (Commentary)

Crystallization (Comment) Organism
crystals of Cys32Ser-mutant and DTNB-modified enzyme grown using the hanging drop, vapor diffusion method. The 2.0 A X-ray crystal structure of DTNB-modified enzyme shows clear electron density for the TNB group covalently attached to Cys32 in all four molecules of the asymmetric unit, indicating complete and specific modification Pisum sativum

Protein Variants

Protein Variants Comment Organism
C32S the mutation leads to approximately 70% drop in ascorbate peroxidase activity with no effect on guaiacol peroxidase activity, these results indicate that uncharged aromatic substrates and the anionic ascorbate molecule interact with different sites on the enzyme Pisum sativum

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
4.2
-
guaiacol will-type enzyme Pisum sativum
6.1
-
guaiacol Cys32Ser mutant Pisum sativum
9.7
-
guaiacol DTNB-modified enzyme Pisum sativum

Organism

Organism UniProt Comment Textmining
Pisum sativum
-
pea
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
ferrocyanide + H2O2 the Cys32Ser mutation has little effect on the kinetics of ferrocyanide turnover, but the DTNB modification decreases activity by approximately 90% at 300 mM ferrocyanide Pisum sativum ferricyanide + H2O
-
?
guaiacol + H2O2 the DTNB-modified enzyme exhibits full activity Pisum sativum ?
-
?
L-ascorbate + H2O2 the DTNB-modified enzyme exhibits only 1.3% wild-type activity when ascorbate is used as substrate, the DTNB-modified enzyme reacts normally with peroxide to give compound I but the rates of reduction of both compounds I and II by ascorbate are dramatically slowed. The Cys32Ser mutant has one-third wild-type activity. The ascorbate interactions with the enzyme are partly mediated through electrostatic interactions Pisum sativum dehydroascorbate + H2O
-
?
pyrogallol + H2O2 the DTNB-modified enzyme exhibits full activity Pisum sativum 3-hydroxybenzo-1,2-quinone + H2O
-
?

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
additional information
-
additional information substrate: guaiacol, effects of Cys32Ser mutagenesis and DTNB-modification Pisum sativum
160
-
pyrogallol wild-type, Cys32Ser mutant and DTNB-modified enzyme Pisum sativum