EC Number   |
Substrates |
Organism |
Products  |
Reversibility |
|---|
   1.13.11.B6 | linoleate + O2 |
- |
Solanum tuberosum |
(10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate |
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 |
? |
| 1.13.11.B6 | linoleate + O2 |
- |
Arachis hypogaea |
(10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate |
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 |
? |
| 1.13.11.B6 | linoleate + O2 |
- |
Pisum sativum |
(10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate |
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 |
? |
| 1.13.11.B6 | linoleate + O2 |
- |
Pisum sativum |
(10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate |
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 |
? |
| 1.13.11.B6 | linoleate + O2 |
- |
Pisum sativum |
(10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate |
the ratio of 9-hydroperoxy-(10E,12Z)-octadecadienoate to 13-hydroperoxy-(10E,12Z)-octadecadienoate is 3:1 |
? |
| 1.13.11.B6 | linoleate + O2 |
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 |
Momordica charantia |
(10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate |
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 |
? |
| 1.13.11.B6 | linoleate + O2 |
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 |
Pisum sativum |
(10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate |
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) |
? |
| 1.13.11.B6 | linoleate + O2 |
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 |
Zea mays |
(10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate |
- |
? |
| 1.13.11.B6 | linolenate + O2 |
- |
Zea mays |
(10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate |
the enzyme forms (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate and (10E,12Z)-9-hydroperoxy-10,12-octadecadienoate in a 6:4 ratio. The R/S stereoconfiguration of the products is not determined |
? |
| 1.13.11.B6 | (9Z,12Z)-octadeca-9,12-dienoic acid + O2 |
i.e. linoleic acid |
Lasiodiplodia theobromae |
(12Z)-9-hydroxy-10-oxo-12-octadecenoic acid |
the alpha-ketol is the main metabolite formed from (9R)-hydroperoxyoctadecadienoic acid |
? |
