Information on EC 5.4.4.5 - 9,12-octadecadienoate 8-hydroperoxide 8R-isomerase

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
5.4.4.5
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RECOMMENDED NAME
GeneOntology No.
9,12-octadecadienoate 8-hydroperoxide 8R-isomerase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
(8R,9Z,12Z)-8-hydroperoxyoctadeca-9,12-dienoate = (5S,8R,9Z,12Z)-5,8-dihydroxyoctadeca-9,12-dienoate
show the reaction diagram
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
Linoleic acid metabolism
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SYSTEMATIC NAME
IUBMB Comments
(8R,9Z,12Z)-8-hydroperoxyoctadeca-9,12-dienoate hydroxymutase [(5S,8R,9Z,12Z)-5,8-dihydroxyoctadeca-9,12-dienoate-forming]
The enzyme contains heme [3]. The bifunctional enzyme from Aspergillus nidulans uses different heme domains to catalyse two separate reactions. Linoleic acid is oxidized within the N-terminal heme peroxidase domain to (8R,9Z,12Z)-8-hydroperoxyoctadeca-9,12-dienoate (cf. EC 1.13.11.60, linoleate 8R-lipoxygenase), which is subsequently isomerized to (5S,8R,9Z,12Z)-5,8-dihydroxyoctadeca-9,12-dienoate within the C-terminal P-450 heme thiolate domain [3].
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
(8R,9Z,12Z)-8-hydroperoxy-10,12-octadecadienoate
(7S,8S,9Z,12Z)-7,8-dihydroxyoctadeca-9,12-dienoate
show the reaction diagram
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?
(8R,9Z,12Z)-8-hydroperoxy-9,12-octadecadienoate
(5S,8R,9Z,12Z)-5,8-dihydroxy-9,12-octadecadienoate
show the reaction diagram
(8R,9Z,12Z)-9-hydroperoxy-10,12-octadecadienoate
(5S,8R,9Z,12Z)-5,8-dihydroxyoctadeca-9,12-dienoate
show the reaction diagram
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?
NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
(8R,9Z,12Z)-8-hydroperoxy-10,12-octadecadienoate
(7S,8S,9Z,12Z)-7,8-dihydroxyoctadeca-9,12-dienoate
show the reaction diagram
C1KH66
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?
(8R,9Z,12Z)-8-hydroperoxy-9,12-octadecadienoate
(5S,8R,9Z,12Z)-5,8-dihydroxy-9,12-octadecadienoate
show the reaction diagram
COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
heme
PpoA contains a high spin ferriheme. PpoA uses different heme domains to catalyze two separate reactions. Within the heme peroxidase domain, linoleic acid is oxidized to (8R,9Z,12Z)-8-hydroperoxy-9,12-octadecadienoate by abstracting a H-atom from C-8 of the fatty acid, yielding a carbon-centered radical that reacts with molecular dioxygen. In the second reaction step, (8R,9Z,12Z)-8-hydroperoxy-9,12-octadecadienoate is isomerized within the P450 heme thiolate domain to (5S,8R,9Z,12Z)-5,8-dihydroxy-9,12-octadecadienoate
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
additional information
suicide inactivation, activity falls to zero within a few min although substrates are available in sufficient amounts
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
additional information
additional information
kinetic data of truncated enzymes
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
3.2
pH 7.2, 24°C
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
110000
4 * 110000, SDS-PAGE
440000
gel filtration
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
tetramer
4 * 110000, SDS-PAGE
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expression in Escherichia coli
expression in Escherichia coli and in insect cells
ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
C1006S
the hydroperoxide isomerase activity of 5,8-LDS mutant is abolished
Y374F
mutation in the conserved sequence YRWH results in loss of linoleate 8R-lipoxygenase activity, whereas the hydroperoxide isomerase activity is retained
H1004A
mutant enzyme with abolished 8-hydroperoxide isomerase activity, whereas dioxygenase activity is still present
Y374
the mutant enzyme shows no detectable activity when incubated with (8R,9Z,12Z)-8-hydroperoxy-9,12-octadecadienoate as a substrate. When incubated with the intermediate product (8R,9Z,12Z)-8-hydroperoxy-9,12-octadecadienoateit it is able to catalyze isomerization to (5S,8R,9Z,12Z)-5,8-dihydroperoxy-9,12-octadecadienoate
additional information
replacements of Tyr and Cys in the conserved YRWH and FXXGPHXCLG sequences abolishes 8R-dioxygenase (8-DOX) and hydroperoxide isomerase activities, respectively. Val328 of 5,8-LDS does not influence the position of oxygenation