EC Number | Cloned (Comment) | Organism |
---|---|---|
1.13.11.B6 | expressed as a His-tagged fusion protein in Escherichia coli | Momordica charantia |
EC Number | Protein Variants | Comment | Organism |
---|---|---|---|
1.13.11.B6 | Q599F | the wild-type enzyme is a linoleate 13-LOX above pH 7.5, below this value it functions as a linoleate 9-LOX. The mutant loses its 13-LOX activity at higher pH-values. At pH-values above 7.5 a rather unspecific product pattern (1:1 ratio of 13-hydroperoxy-(10E,12Z)-octadecadienoate and 9-hydroperoxy-(10E,12Z)-octadecadienoate) is observed with the mutant enzyme. The unspecific oxygenation reaction is also indicated by the R/S-ratio (4:6) of the major reaction products | Momordica charantia |
1.13.11.B6 | Q599H | the mutation converts the enzyme to a linoleate 13-LOX lacking any pH sensitivity. The pH optimum remains unaffected, and the major product isomers are in the S-configuration | Momordica charantia |
1.13.11.12 | Q599H | converts the enzyme to a pure 13-LOX | Momordica charantia |
EC Number | Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
---|---|---|---|---|
1.13.11.B6 | 99500 | - |
x * 99500, calculated from sequence | Momordica charantia |
EC Number | Organism | UniProt | Comment | Textmining |
---|---|---|---|---|
1.13.11.B6 | Momordica charantia | B7FDE5 | - |
- |
1.13.11.12 | Momordica charantia | B7FDE5 | - |
- |
EC Number | Source Tissue | Comment | Organism | Textmining |
---|---|---|---|---|
1.13.11.B6 | seed | - |
Momordica charantia | - |
1.13.11.12 | seed | - |
Momordica charantia | - |
EC Number | Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|---|
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 | ? | |
1.13.11.12 | linoleic acid + O2 | - |
Momordica charantia | (9Z,11E)-(13S)-13-hydroperoxyoctadeca-9,11-dienoic acid | at pH-values higher than 7.5 the enzyme constitutes a linoleate 13-LOX whereas at lower pH, 9-H(P)ODE is the major reaction product. Glutamine 599 plays a role in pH-dependence of the reaction specificity | ? |
EC Number | Subunits | Comment | Organism |
---|---|---|---|
1.13.11.B6 | ? | x * 99500, calculated from sequence | Momordica charantia |
EC Number | Synonyms | Comment | Organism |
---|---|---|---|
1.13.11.B6 | MoLOX1 | - |
Momordica charantia |
1.13.11.12 | LOX | - |
Momordica charantia |
EC Number | pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|---|
1.13.11.B6 | 8 | - |
- |
Momordica charantia |