Literature summary for 1.11.1.11 extracted from

Turner, D.D.; Lad, L.; Kwon, H.; Basran, J.; Carr, K.H.; Moody, P.C.E.; Raven, E.L.
The role of Ala134 in controlling substrate binding and reactivity in ascorbate peroxidase (2018), J. Inorg. Biochem., 180, 230-234 .

Search for more literature for 1.11.1.11

Protein Variants

Protein Variants	Comment	Organism
A143P	site-directed mutagenesis of the delta-site of substrate oxidation, the electronic absorption spectra and dissociation constants for binding of cyanide and azide to the isolated heme are not significantly different for the mutant compared to wild-type, also the rate constants in the peroxidase reaction mechanism are not significantly affected by the replacement of A134 by proline. The insertion of a proline does not substantially alter the product distribution in APX	Pisum sativum
additional information	attempts to decrease heme accessibility through introduction of a Phe residue at position134 are unsuccessful because the A134F variant is isolated as the apoform from Escherichia coli and reconstitution protocols with exogenous heme do not generate catalytically active enzyme	Pisum sativum

Inhibitors

Inhibitors	Comment	Organism	Structure
phenylhydrazine	a suicide substrate	Pisum sativum

KM Value [mM]

KM Value [mM]	KM Value Maximum [mM]	Substrate	Comment	Organism	Structure
additional information	-	additional information	pre-steady state and steady-state kinetic analysis of wild-type and mutant enzymes, formation of high-valent Compound I and Compound II intermediates, detailed overview. The steady-state oxidation of ascorbate by APX does not obey simple Michaelis-Menten kinetics, and a sigmoidal dependence of rate on substrate concentration is observed. The mutant A134P variant behaves similarly. In contrast, oxidation of guaiacol by A134P exhibits conventional Michaelis-Menten type kinetics	Pisum sativum

Localization

Localization	Comment	Organism	GeneOntology No.	Textmining
cytosol	-	Pisum sativum	5829	-

Metals/Ions

Metals/Ions	Comment	Organism	Structure
Fe2+	in the heme group	Pisum sativum

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
2 L-ascorbate + H2O2 + 2 H+	Pisum sativum	-	L-ascorbate + L-dehydroascorbate + 2 H2O	-	?

Organism

Organism	UniProt	Comment	Textmining
Pisum sativum	P48534	-	-

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
2 L-ascorbate + H2O2 + 2 H+	-	Pisum sativum	L-ascorbate + L-dehydroascorbate + 2 H2O	-	?
guaiacol + H2O2	-	Pisum sativum	?	-	?
additional information	there are two main sites for substrate oxidation. The first, close to the gamma-heme edge, is used by ascorbate peroxidase and is presumed to be the main physiological binding site. The second site is close to the delta-heme edge. Role of Ala134 in controlling peroxidase reactivity at the delta-heme edge, overview. Assaying with L-ascorbate, guaiacol and 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonic acid	Pisum sativum	?	-	-

Synonyms

Synonyms	Comment	Organism
APX	-	Pisum sativum
APX1	-	Pisum sativum
ascorbate peroxidase	-	Pisum sativum

Temperature Optimum [°C]

Temperature Optimum [°C]	Temperature Optimum Maximum [°C]	Comment	Organism
25	-	assay at	Pisum sativum

pH Optimum

pH Optimum Minimum	pH Optimum Maximum	Comment	Organism
7	-	assay at	Pisum sativum

Cofactor

Cofactor	Comment	Organism	Structure
heme	ascorbate peroxidase binds some substrates at the gamma-heme edge	Pisum sativum

General Information

General Information	Comment	Organism
evolution	ascorbate peroxidase (APX) is a class I heme peroxidase. Heme peroxidases catalyse the H2O2-dependent oxidation of a wide variety of substrates. The family of heme peroxidases share a common mechanism of oxidation which involves the formation of high-valent Compound I and Compound II intermediates. Ascorbate peroxidase and manganese peroxidase bind some substrates at the gamma-heme edge, others at the delta-heme edge	Pisum sativum

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Release 2023.1 (January 2023)