Information on EC 1.14.19.22 - acyl-lipid omega-6 desaturase (cytochrome b5)

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The expected taxonomic range for this enzyme is: Eukaryota, Bacteria

EC NUMBER
COMMENTARY hide
1.14.19.22
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RECOMMENDED NAME
GeneOntology No.
acyl-lipid omega-6 desaturase (cytochrome b5)
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
an oleoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = a linoleoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H2O
show the reaction diagram
; also desaturates phosphatidylcholines containing the oleoyl group on O-2 of the glycerol residue
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REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
oxidation
redox reaction
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reduction
PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
linoleate biosynthesis I (plants)
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phospholipid desaturation
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SYSTEMATIC NAME
IUBMB Comments
1-acyl-2-oleoyl-sn-glycero-3-phosphocholine,ferrocytochrome-b5:oxygen oxidoreductase (12,13 cis-dehydrogenating)
This microsomal enzyme introduces a cis double bond in fatty acids attached to lipid molecules at a location 6 carbons away from the methyl end of the fatty acid. The distance from the carboxylic acid end of the molecule does not affect the location of the new double bond. The most common substrates are oleoyl groups attached to either the sn-1 or sn-2 position of the glycerol backbone in phosphatidylcholine. cf. EC 1.14.19.23, acyl-lipid omega-6 desaturase (ferredoxin).
CAS REGISTRY NUMBER
COMMENTARY hide
59929-36-1
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ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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Manually annotated by BRENDA team
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Manually annotated by BRENDA team
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Manually annotated by BRENDA team
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Manually annotated by BRENDA team
cultivar Acala SJ2
UniProt
Manually annotated by BRENDA team
lupin
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Manually annotated by BRENDA team
cultivar Wisconsin 38
UniProt
Manually annotated by BRENDA team
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Manually annotated by BRENDA team
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Manually annotated by BRENDA team
isoform FAD2, intron-mediated regulatory mechanism controls both the seed-specific expression of enzyme gene and the expression of plant FAD2 gene
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Manually annotated by BRENDA team
potato
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Manually annotated by BRENDA team
NT-1
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Manually annotated by BRENDA team
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SwissProt
Manually annotated by BRENDA team
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Manually annotated by BRENDA team
maize
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Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
malfunction
metabolism
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the enzyme is involved in providing polyunsaturated phosphatidylcholine to the chloroplast envelope
physiological function
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
1,2-di-oleoyl-sn-glycero-3-phosphorylcholine + 2 ferrocytochrome b5 + O2 + 2 H+
1,2-di-linoleoyl-sn-glycero-3-phosphorylcholine + 2 ferricytochrome b5 + 2 H2O
show the reaction diagram
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desaturation takes place at both position-1 and position-2. The distearoyl or dielaidoyl phosphatidylcholines are not desaturated
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?
1,2-di-oleoyl-sn-glycero-3-phosphorylcholine + O2 + ?
?
show the reaction diagram
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?
1,2-dioleoylphosphatidylcholine + 2 ferrocytochrome b5 + O2 + 2 H+
1,2-linoleoylphosphatidylcholine + 2 ferricytochrome b5 + 2 H2O
show the reaction diagram
1-acyl-2-oleoyl-sn-glycero-3-phosphocholine + ferrocytochrome b5 + O2 + H+
1-acyl-2-linoleoyl-sn-glycero-3-phosphocholine + ferricytochrome b5 + H2O
show the reaction diagram
1-acyl-2-oleoyl-sn-glycero-3-phosphorylcholine + 2 ferrocytochrome b5 + O2 + 2 H+
1-acyl-2-linoleoyl-sn-glycero-3-phosphorylcholine + 2 ferricytochrome b5 + 2 H2O
show the reaction diagram
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-
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?
1-palmitoyl-2-oleoyl phosphatidylcholine + NAD+
1-palmitoyl-2-linoleoyl phosphatidylcholine + NADH
show the reaction diagram
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?
1-stearoyl-2-oleoyl phosphatidylcholine + NAD+
1-stearoyl-2-linoleoyl phosphatidylcholine + NADH
show the reaction diagram
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-
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-
?
oleoyl-phosphatidylcholine + 2 ferrocytochrome b5 + O2 + 2 H+
linoleoyl-phosphatidylcholine + 2 ferricytochrome b5 + 2 H2O
show the reaction diagram
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?
oleoyl-[CoA] + ferrocytochrome b5 + O2 + H+
linoleoyl-[CoA] + ferricytochrome b5 + H2O
show the reaction diagram
oleoyl-[CoA] + phosphatidylcholine + O2 + H+
?
show the reaction diagram
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?
oleoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+
linoleoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H2O
show the reaction diagram
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the IgG fraction from ascites fluid inhibits 62% of NADH-dependent cytochrome c reduction in safflower (Carthamus tinctorius L.) microsomes. These antibodies also block desaturation of oleic acid to linoleic acid in lipids of Carthamus tinctorius microsomes by 93%, suggesting that cytochrome b5 is the electron donor for the DELTA12 desaturase
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?
oleoyl-[glycerolipid] + ferrocytochrome b5 + O2 + H+
linoleoyl-[glycerolipid] + ferricytochrome b5 + H2O
show the reaction diagram
oleoyl-[glycerolipid] + reduced ferredoxin [iron-sulfur] cluster + O2 + H+
linoleoyl-[glycerolipid] + oxidized ferredoxin [iron-sulfur] cluster + H2O
show the reaction diagram
the enzyme inserts a double bond between the carbons 12 and 13 of monounsaturated oleic acid to generate polyunsaturated linoleic acid
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?
palmitoyl-[glycerolipid] + ferrocytochrome b5 + O2 + H+
hexadecadienoyl-[glycerolipid] + ferricytochrome b5 + H2O
show the reaction diagram
additional information
?
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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
1-acyl-2-oleoyl-sn-glycero-3-phosphocholine + ferrocytochrome b5 + O2 + H+
1-acyl-2-linoleoyl-sn-glycero-3-phosphocholine + ferricytochrome b5 + H2O
show the reaction diagram
oleoyl-[CoA] + ferrocytochrome b5 + O2 + H+
linoleoyl-[CoA] + ferricytochrome b5 + H2O
show the reaction diagram
oleoyl-[CoA] + phosphatidylcholine + O2 + H+
?
show the reaction diagram
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?
oleoyl-[glycerolipid] + ferrocytochrome b5 + O2 + H+
linoleoyl-[glycerolipid] + ferricytochrome b5 + H2O
show the reaction diagram
oleoyl-[glycerolipid] + reduced ferredoxin [iron-sulfur] cluster + O2 + H+
linoleoyl-[glycerolipid] + oxidized ferredoxin [iron-sulfur] cluster + H2O
show the reaction diagram
Q6DMQ8
the enzyme inserts a double bond between the carbons 12 and 13 of monounsaturated oleic acid to generate polyunsaturated linoleic acid
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?
palmitoyl-[glycerolipid] + ferrocytochrome b5 + O2 + H+
hexadecadienoyl-[glycerolipid] + ferricytochrome b5 + H2O
show the reaction diagram
additional information
?
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a desaturase mutant that is unable to convert oleic acid to linoleic acid is impaired in polyunsaturated fatty acid biosynthesis, shows delayed spore germination, a twofold reduction in growth, a reduced level of conidiation and complete loss of eclerotial development, compared to the wild-type
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
cytochrome b5
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NADH-cytochrome b5 reductase
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required for activity
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Mg2+
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required
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
8-hydroxyquinoline
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76% residual activity at 1 mM
CN-
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15% residual activity at 1 mM
cyanide
mycobactin
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81% residual activity at 1 mM
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o-phenanthroline
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83% residual activity at 1 mM
oleate desaturase siRNA
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p-chloromercuribenzoate
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28% residual activity at 2 mM
sn-glycero-3-phosphocholine
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Thenoyltrifluoroacetone
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additional information
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
abscisic acid
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increase in enzyme gene expression
O2
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elevation of external O2 supply produces a dramatic increase of the FAD2 enzyme activity
Triton X-100
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at an optimal concentration of 0.1% Triton X-100, the detergent increases the rate of desaturation about three fold
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.95
1,2-di-oleoyl-sn-glycero-3-phosphorylcholine
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; pH 7.4, 37C
0.25
1-acyl-2-oleoyl-sn-glycero-3-phosphocholine
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0.25
1-acyl-2-oleoyl-sn-glycero-3-phosphorylcholine
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pH 7.4, 37C
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
TEMPERATURE RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
10 - 40
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10C: about 50% of maximal activity, 40C: about 40% of maximal activity
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
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detached, fast and dramatic increase or decrease in the level of enzyme activity in response to a temperature change from 30C to 10C, or from 10C to 30C
Manually annotated by BRENDA team
young drupe; young drupe; young drupe
Manually annotated by BRENDA team
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accumulates in leaf mesophyll cells when exposed to 15C for 4 days in dark conditions
Manually annotated by BRENDA team
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Manually annotated by BRENDA team
additional information
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
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omega-6 fatty acid desaturase fad2
Manually annotated by BRENDA team
additional information
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extra-plastidial
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Manually annotated by BRENDA team
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
43600
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calculated from cDNA
43900
x * 43900, calculated
44300
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calculated from cDNA
44340
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calculated from cDNA
52000
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x * 52000, calculated from amino acid sequence
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
POSTTRANSLATIONAL MODIFICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
10 - 30
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temperature changes from 10C to 30C or vice versa bring about a fast and dramatic decrease or increase in the level of FAD2 activity, respectively
20 - 32
no difference in FAD2 expression is found in plants grown between 20C and 32C, isozymes FAD2-3 and FAD2-4 are induced under cold stress, FAD2-4 induction is significantly higher than FAD2-3, in contrast isozyme FAD2-2 is not affected by cold
30
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30 min, maximal activity until
34
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30 min, 50% loss of activity
45
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30 min, complete loss of activity
additional information
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low thermal stability
GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
removal of hulls followed by incubation in air does not change the activity level of the enzyme, whereas incubation under nitrogen causes strong decrease
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when peeled seeds are incubated at 10C for 14 h, the enzyme activity remains constant
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OXIDATION STABILITY
ORGANISM
UNIPROT
LITERATURE
low internal oxygen levels (0.001 mM) limit FAD2 activity, the internal oxygen level acts as a key regulator for the activity of the FAD2 enzyme
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688081
O2 concentration less than 3% produces inactivation of the enzyme
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655775
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
CeFAT-2 is expressed under the control of an inducible Gal1 promoter in Saccharomyces cerevisiae
expresed in yeast cells
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expressed in Escherichia coli
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expressed in Escherichia coli BL21(DE3) cells
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expressed in Saccharomyces cerevisiae
expressed in Solanum tuberosum leaves as fusion protein with thermostable lichenase
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expressed in yeast cells
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expression in Saccahromyces cerevisae
flag-tagged enzyme is functionally expressed in yeast cells. To express the gene in thraustochytrids, a construct driven by the thraustochytrid-derived ubiquitin promoter is used
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functional expression in Saccharomyces cerevisiae
gene desA, expression profile analysis, construction of a hybrid of desA and reporter gene encoding thermostable lichenase, licBM3, and expression in Escherichia coli strain XL1blue and Solanum tuberosum cells, the latter via Agrobacterium tumefaciens strain AGLO transfection. The desaturase can enhance tolerance to cold stress in potato, and desaturase and lichenase retain their functionality in the structure of a recombinant hybrid protein where the enzymatic activity of target gene product is higher than in the case of reporter lichenase gene absence in the construction
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recombinantly expressed in Saccharomyces cerevisiae and Pichia Pastoris
the pGEM-T Easy vector is used
EXPRESSION
ORGANISM
UNIPROT
LITERATURE
expression levels of OsFAD2 are markedly decreased in shoots treated with kinetin and gibberellins
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expression levels of OsFAD2 are markedly increased in shoots treated with 6-benzyladenine
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the expression level remains approximately constant for at least 3 days after transfer to the cold (22 to 6C)
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
A104G
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2.1fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
A104G/M324V
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2.6fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
A104G/S322A
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3.1fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
A104G/S322A/M324V
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4.3fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
A104G/T148I
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29.5fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
A104G/T148I/M324V
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36.1fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
A104G/T148I/S322A
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44.3fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
A104G/T148I/S322A/M324V
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90.2fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
A104G/T148N/S322A/M324I
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24.6fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
M324I
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54.1fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
M324V
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49.2fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
S322A
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1.3fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
S322A/M324V
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2.1fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
T148I
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14.8fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
T148I/M324V
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26.2fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
T148I/S322A
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26.2fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
T148I/S322A/M324V
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34.4fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
T148N
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3.3fold increase in the ratio of hydroxylation to desaturation compared to wild-type enzyme
D150N
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the mutation of the ahFAD2 gene results in a dysfunctional desaturase
G374E
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line 743, missense mutations in a less conserved region, seed phenotype does not differ from wild-type
P137R
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the PI 283327 FAD2-1B allele, carrying the mutant FAD2-1B P137R allele, is associated with an increase in seed oleic acid content
S238F
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line 615, missense mutations in a less conserved region, seed phenotype does not differ from wild-type
additional information
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mutation Ol greatly increases oleic acid and is correlated with greatly reduced expression of enzyme isoform FAD2-1. FAD2-1 gene is duplicated in Ol mutants. Development of dominant INDEL markers diagnostic for presence or absence of the Ol mutation
APPLICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
agriculture
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mutation Ol greatly increases oleic acid and is correlated with greatly reduced expression of enzyme isoform FAD2-1. FAD2-1 gene is duplicated in Ol mutants. Development of dominant INDEL markers diagnostic for presence or absence of the Ol mutation
medicine
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use of enzyme as a molecular target for the development of chemotherapeutic approaches against Chagas disease