1.13.11.B6: linoleate 9/13-lipoxygenase

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(9Z,12Z)-octadeca-9,12-dienoic acid + O2

(12Z)-9-hydroxy-10-oxo-12-octadecenoic acid

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i.e. linoleic acid

the alpha-ketol is the main metabolite formed from (9R)-hydroperoxyoctadecadienoic acid

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i.e. linoleic acid

the alpha-ketol is the main metabolite formed from (9R)-hydroperoxyoctadecadienoic acid

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i.e. linoleic acid

the alpha-ketol is the main metabolite formed from (9R)-hydroperoxyoctadecadienoic acid

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i.e. linoleic acid

the alpha-ketol is the main metabolite formed from (9R)-hydroperoxyoctadecadienoic acid

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(9Z,12Z)-octadeca-9,12-dienoic acid + O2

(9S,10E,12Z)-9-hydroperoxy-octadeca-10,12-dienoate

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alpha-linoleate is converted via two intermediates, (9Z,11S,12Z)-11-hydroperoxy-9,12-octadecenoate and (9Z,11E,13R)-13-hydroperoxy-9,12-octadecadienoate, which are isomerized to the end product, probably after oxidation to peroxyl radicals, beta-fragmentation, and oxygen insertion at C-9

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alpha-linoleate is converted via two intermediates, (9Z,11S,12Z)-11-hydroperoxy-9,12-octadecenoate and (9Z,11E,13R)-13-hydroperoxy-9,12-octadecadienoate, which are isomerized to the end product, probably after oxidation to peroxyl radicals, beta-fragmentation, and oxygen insertion at C-9

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(9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid + O2

(9R,10E,12Z,15Z)-9-hydroperoxyoctadeca-10,12,15-trienoic acid + (9Z,12Z,15Z)-9-hydroxy-10-oxooctadeca-12,15-dienoic acid

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i.e. alpha-linoleic acid

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i.e. alpha-linoleic acid

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i.e. alpha-linoleic acid

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i.e. alpha-linoleic acid

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(9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid + O2

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gamma-linoleate is oxidized at C-9, C-11, and C-13

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gamma-linoleate is oxidized at C-9, C-11, and C-13

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2-linoleoyl-sn-glycero-3-phosphorylcholine + O2

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low activity of wild-type and A562G mutant. The wild-type enzyme predominantly produces (13S)-hydroperoxide. The A562G mutant form possesses lesser regio- and stereospecificity during the dioxygenation of lysoPC. It produces 28% of (10E,12Z)-9-hydroperoxide and 30% of (9Z,11E)-13-hydroperoxide along with 41% of (all-E)-hydroperoxides. While 9-hydroperoxide is present mainly (61%) as S-enantiomer, (9Z,11E)-13-hydroperoxide is nearly racemic

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the wild-type ZmLOX produces predominantly (13S)-hydroperoxide. In contrast, the A562G mutant produces excessively (9S)-hydroperoxide. The oxidation of 2-linoleoyl-sn-glycero-3-phosphorylcholine exhibits the limited regio- and stereospecificity. But the A562G mutant form possesses lesser regio- and stereospecificity

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all-cis-9,12,15-octadecatrienoic acid + O2

(9R)-hydroperoxy-(10E,12Z,15Z)-octadecatrienoic acid + 9-hydroxy-10-oxo-(12Z,15Z)-octadecadienoic acid

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i.e. alpha-linoleic acid

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i.e. alpha-linoleic acid

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i.e. alpha-linoleic acid

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i.e. alpha-linoleic acid

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linoleate + O2

(10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate

Arachis hypogaea

Q9M5D3

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706250

the linoleic acid oxidation products are ca. 70% and (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate and 30% (10E,12Z)-9-hydroperoxy-10,12-octadecadienoate both of which are mainly the S-stereoisomer

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Momordica charantia

B7FDE5

according to their positional specificity of linoleic acid oxygenation plant LOX can be classified into linoleate 9-lipoxygenases and linoleate 13-lipoxygenases. A critical valine is detected at the active site of 9-LOX. In contrast, more bulky phenylalanine or histidine residues are found at this position in 13-LOX. Cloning of LOX-isoform from Momordica charantia and multiple amino acid alignments indicate the existence of a glutamine (Gln599) at the position where 13-LOX usually carry histidine or phenylalanine residues. Analyzing the pH-dependence of the positional specificity of linoleic acid oxygenation it is observed that at pH-values higher than 7.5 this enzyme constitutes a linoleate 13-lipoxygenase whereas at lower pH, (9S)-hydroperoxy-(10E,12Z)-octadecadienoate is the major reaction product. The structural basis for this variable reaction specificity is explored by site directed mutagenesis studies. Site-directed mutagenesis of Gln599 to His (Gln599His) converts the enzyme to a pure 13-lipoxygenase. The reaction specificity of certain LOX-isoforms is not an absolute enzyme property but may be impacted by reaction conditions such as pH of the reaction mixture

706122

variable positional specificity of linoleic acid oxygenation depending on the pH of the reaction mixture. Below pH 7.5, (10E,12Z)-9-hydroperoxy-10,12-octadecadienoate is the major reaction product whereas at higher pH (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate is dominant. (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate is preferentially formed as S enantiomer (85%) and the S/R-ratio does hardly vary over the entire pH-range. In contrast, the enantiomers composition of (10E,12Z)-9-hydroperoxy-10,12-octadecadienoate is pH-dependent. Below pH 7.5 a strong preponderance of the S enantiomer is observed. At higher pH-values the relative share of (9R,10E,12Z)-9-hydroperoxy-10,12-octadecadienoate becomes increasingly abundant reaching a 1:1 ratio at pH 9

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Pisum sativum

P09918, P14856

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396184

the ratio of (9Z,11E)-13-hydroperoxy-11,13-octadecadienoate to (10E,12Z)-9-hydroperoxy-10,12-octadecadienoate is 1:2 for pea seed LOX-3 and recombinant LOX-3. The R/S stereoconfiguration of the products is not determined

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P09918, P14856

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396184

the ratio of (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate to (10E,12Z)-9-hydroperoxy-10,12-octadecadienoate is 4:1 for LOX-2 from from pea seed and 7:1 for the recombinant enzyme LOX-2. The R/S stereoconfiguration of the product is not determined

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Q14ST9

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706289

the ratio of 9-hydroperoxy-(10E,12Z)-octadecadienoate to 13-hydroperoxy-(10E,12Z)-octadecadienoate is 3:1

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identification of some of the primary determinants at the catalytic centre of pea 9/13-LOX. Validation of a model of linoleate-binding to this enzyme. Evidence is provided that the primary determinants of pocket volume and conformation are more important than substrate orientation in pea lipoxygenase catalysis. Inverse models may account for the positional specificity of only selected plant lipoxygenases

703535

ratio of (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate to (10E,12Z)-9-hydroperoxy-10,12-octadecadienoate: 1.1 (wild-type enzyme), 1.6 (mutant enzyme T579S), 1.5 (mutant enzyme V570I), 1.4 (mutant enzyme T579F), 1.3 (mutant enzyme F580A), 0.9 (mutant enzyme L569V), 1.7 (mutant enzyme W523A), 1.3 (mutant enzyme F580V)

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Solanum tuberosum

Q9SC16

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396190

dual positional specificity: the enzyme produces roughly equimolar amounts of (10E,12Z)-9-hydroperoxy-10,12-octadecadienoate and (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate. The R/S stereoconfiguration of the products is not determined

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the dual positional specific maize lipoxygenase is not able to catalyze the oxidation of trilinolein or trilinolenin even in the presence of detergent. The enzyme seems to ultilize only free fatty acid as a substrate. The solubilization of substrate involves the incorporation of substrate molecules into the detergent micelles, which leads to decreased availability of effective free fatty acids for binding with the LOX enzyme. The unique initial burst phenomenon of the maize LOX observed in the oxidation of linoleate at low pH may also be attributed to the availability of free fatty acids as substrates

674388

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linoleate + O2

(9R,10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E,13R)-13-hydroperoxy-9,11-octadecadienoate

Glycine max

P09186

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706645

the enzyme delivers a 50:50 mixture of (9R,10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E,13R)-13-hydroperoxy-9,11-octadecadienoate, with higher turn out of R stereoisomers over S isomers (60:40)

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Malus domestica

S4UKU4, S4UL92

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linoleate + O2

(9S,10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E,13S)-13-hydroperoxy-9,11-octadecadienoate

Corylus avellana

Q93YI8

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703538

(9S,10E,12Z)-9-hydroperoxy-10,12-octadecadienoate is the main product (about 70% of the total hydroperoxides), predominantly S configuration

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Glycine max

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soybean lipoxygenase-1 produces a preponderance of two chiral products from linoleic acid, (9Z,11E,13S)-13-hydroperoxy-9,11-octadecadienoate and (9S,10E,12Z)-9-hydroperoxy-10,12-octadecadienoate. (9Z,11E,13S)-13-hydroperoxy-9,11-octadecadienoate is generated at all pH values, but in the presence of Tween 20, (9S,10E,12Z)-9-hydroperoxy-10,12-octadecadienoate does not form at pH values above 8.5. As the pH decreases below 8.5, the proportion of (9S,10E,12Z)-9-hydroperoxy-10,12-octadecadienoate increases linearly until at pH 6 it constitutes about 25% of the chiral products attributed to enzymic action. Below pH 6, lipoxygenase activity is barely measurable, and the hydroperoxide product arises mainly from autoxidation and possibly non-enzymic oxygenation of the pentadienyl radical formed by the enzyme. The change in percent enzymically formed 9-hydroperoxide between pH 6.0 and 8.5 parallels the pH plot of a sodium linoleate/linoleic acid titration. It is concluded that the (9S)-hydroperoxide is formed only from the nonionized carboxylic acid form of linoleic acid. Methyl esterification of linoleic acid blocks the formation of the (9S,10E,12Z)-9-hydroperoxy-10,12-octadecadienoate by lipoxygenase-1, but not the (13S)-hydroperoxide. Since the hydroperoxydiene moieties of the (9S)- and (13S)-hydroperoxides are spatially identical when the molecules are arranged head to tail in opposite orientations, it is suggested that the carboxylic acid form of the substrate can arrange itself at the active site in either orientation, but the carboxylate anion can be positioned only in one orientation. Active-site model for soybean lipoxygenase-1

702394

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Oryza sativa

Q27PX2

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706252

the ratio of (9Z,11E,13S)-13-hydroperoxy-9,11-octadecadienoate to (9S,10E,12Z)-9-hydroperoxy-10,12-octadecadienoate is 4:3, dual positional specificity. The ratio of (10E,12Z)-9-hydroperoxy-10,12-octadecadienoate to (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate is 4:3. Both products are predominantly in the S configuration

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706252

dual positional specificity. The ratio of (10E,12Z)-9-hydroperoxy-10,12-octadecadienoate to (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate is 4:3. Both products are predominantly in the S configuration

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linolenate + O2

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Malus domestica

S4UKU4, S4UL92

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Olea europaea

B6D1W5

the catalytic efficiency of the recombinant olive LOX is significantly higher for linoleic acid hydroperoxidation than for linolenic acid hydroperoxidation

702431

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Pisum sativum

Q14ST9

specific activity is 17% of the activity with linoleate. The R/S stereoconfiguration of the product is not determined

706289

products not determined

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monolinolenoylglycerol + O2

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isolated from flax leaves, both the wild-type ZmLOX and A562G mutant dioxygenate monolinolenoylglycerol. Both oxidize the monolinolenoylglycerol predominantly into (9S)-hydroperoxide. The A562G mutation does not affect the relative yield of 13-hydroperoxide, but increases the proportion of (13R)-enantiomer

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wild-type enzyme and mutant A562G predominantly produce (9S)-hydroperoxide

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additional information

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the putative 9R-dioxygenase catalyzes stereospecific removal of the 11R hydrogen followed by suprafacial attack of dioxygen at C-9

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the putative 9R-dioxygenase catalyzes stereospecific removal of the 11R hydrogen followed by suprafacial attack of dioxygen at C-9

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the putative 9R-dioxygenase catalyzes stereospecific removal of the 11R hydrogen followed by suprafacial attack of dioxygen at C-9

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the putative 9R-dioxygenase catalyzes stereospecific removal of the 11R hydrogen followed by suprafacial attack of dioxygen at C-9

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Malus domestica

S4UKU4

regio- and stereospecificity analysis of isozyme substrate specificity, recombinant LOX1:Md:1a, LOX1:Md:1c, LOX2:Md:2a and LOX2:Md:2b isozymes show 13/9-LOX, 9-LOX, 13/9-LOX and 13-LOX activity with linoleic acid, respectively. While products of LOX1:Md:1c and LOX2:Md:2b are S-configured, LOX1:Md:1a and LOX2:Md:2a form 13(R)-hydroperoxides as major products. Oxygenation in the carbon backbone of linoleic acid occurs either at carbon atom 9 (9-LOX) or 13 (13-LOX), forming the corresponding hydroperoxy derivatives, respectively. LOX enzymes are not perfectly specific and biocatalysts that produce more than 10% of the alternative regio-isomer are called dual positional specific LOX

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S4UL92

regio- and stereospecificity analysis of isozyme substrate specificity, recombinant LOX1:Md:1a, LOX1:Md:1c, LOX2:Md:2a and LOX2:Md:2b isozymes show 13/9-LOX, 9-LOX, 13/9-LOX and 13-LOX activity with linoleic acid, respectively. While products of LOX1:Md:1c and LOX2:Md:2b are S-configured, LOX1:Md:1a and LOX2:Md:2a form 13(R)-hydroperoxides as major products. Oxygenation in the carbon backbone of linoleic acid occurs either at carbon atom 9 (9-LOX) or 13 (13-LOX), forming the corresponding hydroperoxy derivatives, respectively. LOX enzymes are not perfectly specific and biocatalysts that produce more than 10% of the alternative regio-isomer are called dual positional specific LOX

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regio- and stereospecificity analysis of isozyme substrate specificity, recombinant LOX1:Md:1a, LOX1:Md:1c, LOX2:Md:2a and LOX2:Md:2b isozymes show 13/9-LOX, 9-LOX, 13/9-LOX and 13-LOX activity with linoleic acid, respectively. While products of LOX1:Md:1c and LOX2:Md:2b are S-configured, LOX1:Md:1a and LOX2:Md:2a form 13(R)-hydroperoxides as major products. Oxygenation in the carbon backbone of linoleic acid occurs either at carbon atom 9 (9-LOX) or 13 (13-LOX), forming the corresponding hydroperoxy derivatives, respectively. LOX enzymes are not perfectly specific and biocatalysts that produce more than 10% of the alternative regio-isomer are called dual positional specific LOX

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cf. EC 1.13.11.45, LC- and GC-MS analysis product analysis, overview. Authentic (11S)-hydroperoxyoctadecadienoate is rapidly transformed to 9-hydroperoxyoctadecadienoate by 9S-MnLOX, and only traces of 13-hydroperoxyoctadecadienoate. 9S-MnLOX also partly transforms authentic (13R)-hydroperoxyoctadecadienoate to (9S)-hydroperoxyoctadecadienoate

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cf. EC 1.13.11.45, LC- and GC-MS analysis product analysis, overview. Authentic (11S)-hydroperoxyoctadecadienoate is rapidly transformed to 9-hydroperoxyoctadecadienoate by 9S-MnLOX, and only traces of 13-hydroperoxyoctadecadienoate. 9S-MnLOX also partly transforms authentic (13R)-hydroperoxyoctadecadienoate to (9S)-hydroperoxyoctadecadienoate

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Solanum tuberosum

Q9SC16

the enzyme catalyzes oxidation of arachidonate with lower activity

396190

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the enzyme catalyzes oxidation of arachidonate with lower activity

396190

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both the wild type ZmLOX and A562G mutant dioxygenate monolinolenoylglycerol and 2-linoleoyl-sn-glycero-3-phosphorylcholine, the latter being a poor substrate. Both oxidize the monolinolenoylglycerol predominantly into (9S)-hydroperoxide. The oxidation of 2-linoleoyl-sn-glycero-3-phosphorylcholine exhibits limited regio- and stereospecificity: the wild-type ZmLOX produces some predominance of (13S)-hydroperoxide. In contrast, the A562G mutant produces some excess of (9S)-hydroperoxide

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both the wild type ZmLOX and A562G mutant dioxygenate monolinolenoylglycerol and 2-linoleoyl-sn-glycero-3-phosphorylcholine, the latter being a poor substrate. Both oxidize the monolinolenoylglycerol predominantly into (9S)-hydroperoxide. The oxidation of 2-linoleoyl-sn-glycero-3-phosphorylcholine exhibits limited regio- and stereospecificity: the wild-type ZmLOX produces some predominance of (13S)-hydroperoxide. In contrast, the A562G mutant produces some excess of (9S)-hydroperoxide

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Bulky polar heads of glycerolipids cannot penetrate into the LOX active site. Both (9S)- and (13S)-hydroperoxides can be produced when the substrate is arranged within LOX active site in the methyl end first orientation. 1-Linoleoyl-snglycero-3-phosphorylcholine is a poor substrate for both wild-type and A562G mutant. No activity of wild-type and mutant with 2-O-alpha-linolenoyl-3-O-beta-D-galactopyranosyl-sn-glycerol, dilinolenoylglycerol, and trilinolenoylglycerol

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Bulky polar heads of glycerolipids cannot penetrate into the LOX active site. Both (9S)- and (13S)-hydroperoxides can be produced when the substrate is arranged within LOX active site in the methyl end first orientation. 1-Linoleoyl-snglycero-3-phosphorylcholine is a poor substrate for both wild-type and A562G mutant. No activity of wild-type and mutant with 2-O-alpha-linolenoyl-3-O-beta-D-galactopyranosyl-sn-glycerol, dilinolenoylglycerol, and trilinolenoylglycerol