Cloned (Comment) | Organism |
---|---|
gene LOX1a, RT-PCR and real-time quantitative PCR expression analysis, 22 putative LOX genes in apple, gene expression analysis throughout ripening reveals that only six LOXs are expressed in a ripening-dependent manner, overview. DNA and amino acid sequence determination and analysis, recombinant expression of N-terminally His-tagged or untagged LOX genes endoing for isozymes LOX1:Md:1a, L, X1:Md:1c, LOX2:Md:2a, and LOX2:Md:2b, containing an enterokinase cleavage recognition site in the first case, in Saccharomyces cerevisiae strain INVSc1, recombinant expression of YFP-tagged enzyme | Malus domestica |
gene LOX2a, RT-PCR and real-time quantitative PCR expression analysis, 22 putative LOX genes in apple, gene expression analysis throughout ripening reveals that only six LOXs are expressed in a ripening-dependent manner, overview. DNA and amino acid sequence determination and analysis, recombinant expression of N-terminally His-tagged or untagged LOX genes endoing for isozymes LOX1:Md:1a, L, X1:Md:1c, LOX2:Md:2a, and LOX2:Md:2b, containing an enterokinase cleavage recognition site in the first case, in Saccharomyces cerevisiae strain INVSc1, recombinant expression of YFP-tagged enzyme | Malus domestica |
Protein Variants | Comment | Organism |
---|---|---|
G567A | site-directed mutagenesis, the mutant converts the dual positional specific LOX1:Md:1a to an enzyme with a high specificity for 9(S)-hydroperoxide formation | Malus domestica |
G567A | site-directed mutagenesis, the mutant converts the dual positional specific LOX1:Md:1a to an enzyme with a high specificity for 9(S)-hydroperoxide formation, mutant substrate specificity compared to the wild-type enzyme, chiral analysis | Malus domestica |
I566F | site-directed mutagenesis, inactive mutant | Malus domestica |
I578L | site-directed mutagenesis, mutant substrate specificity compared to the wild-type enzyme, chiral analysis | Malus domestica |
L572I | site-directed mutagenesis, inactive mutant | Malus domestica |
additional information | mutants Arg268Ala, Gly567Ala, Ile578Leu and Val582Phe show high substrate conversion rates of linoleate, linolenate and arachidonate (60%-100% of wild-type LOX1:Md:1a activity with linoleate). Substrate specificity of mutants, overview | Malus domestica |
R268A | site-directed mutagenesis, mutant substrate specificity compared to the wild-type enzyme, chiral analysis | Malus domestica |
V582F | site-directed mutagenesis, mutant substrate specificity compared to the wild-type enzyme, chiral analysis | Malus domestica |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
additional information | - |
additional information | Michaelis-Menten kinetics | Malus domestica |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
additional information | not in chloroplasts | Malus domestica | - |
- |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
linoleate + O2 | Malus domestica | - |
(9R,10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E,13R)-13-hydroperoxy-9,11-octadecadienoate | - |
? | |
linoleate + O2 | Malus domestica | - |
9-hydroperoxy-10,12-octadecadienoate + 13-hydroperoxy-9,11-octadecadienoate | - |
? | |
linolenate + O2 | Malus domestica | - |
? | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Malus domestica | S4UKU4 | LOX2:Md:2a | - |
Malus domestica | S4UL92 | LOX1:Md:1a | - |
Purification (Comment) | Organism |
---|---|
recombinant His-tagged enzymes from Saccharomyces cerevisiae strain INVSc1 by nickel affinity chromatographyand ultrafiltration | Malus domestica |
Source Tissue | Comment | Organism | Textmining |
---|---|---|---|
fruit | expression analysis of isozymes | Malus domestica | - |
fruit | high expression level of isozyme MdLOX1a gene in stored apple fruit, expression analysis of isozymes | Malus domestica | - |
additional information | no visible PCR bands from isozymes MdLOX1d, MdLOX4a, MdLOX5d, MdLOX5e and MdLOX9a during fruit development | Malus domestica | - |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
linoleate + O2 | - |
Malus domestica | (9R,10E,12Z)-9-hydroperoxy-10,12-octadecadienoate + (9Z,11E,13R)-13-hydroperoxy-9,11-octadecadienoate | - |
? | |
linoleate + O2 | - |
Malus domestica | 9-hydroperoxy-10,12-octadecadienoate + 13-hydroperoxy-9,11-octadecadienoate | - |
? | |
linolenate + O2 | - |
Malus domestica | ? | - |
? | |
additional information | 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 | Malus domestica | ? | - |
? |
Subunits | Comment | Organism |
---|---|---|
? | x * 101500, recombinant His-tagged isozyme LOX1a, SDS-PAGE | Malus domestica |
? | x * 106500, recombinant His-tagged isozyme LOX2a, SDS-PAGE | Malus domestica |
Synonyms | Comment | Organism |
---|---|---|
dual positional specific LOX | - |
Malus domestica |
linoleate oxygen oxidoreductase | - |
Malus domestica |
lipoxygenase | - |
Malus domestica |
LOX | - |
Malus domestica |
LOX1:Md:1a | - |
Malus domestica |
LOX1a | - |
Malus domestica |
LOX2:Md:2a | - |
Malus domestica |
LOX2a | - |
Malus domestica |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
35 | - |
- |
Malus domestica |
45 | - |
- |
Malus domestica |
Temperature Minimum [°C] | Temperature Maximum [°C] | Comment | Organism |
---|---|---|---|
15 | 45 | isozyme LOX2:Md:2a shows negligible activity at temperatures higher than 45°C | Malus domestica |
15 | 55 | isozyme LOX1:Md:1a shows a rather narrow optimum at 45°C with rapidly decreasing activity at lower or higher temperatures, but high residual activity at 55°C | Malus domestica |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
6 | - |
- |
Malus domestica |
7 | - |
- |
Malus domestica |
pH Minimum | pH Maximum | Comment | Organism |
---|---|---|---|
4.5 | 8 | over 60% of maxmal activity within this range | Malus domestica |
5 | 7.5 | over 80% of maximal activity in a broad pH range with sharply decreasing relative activity below pH 5.0 and above pH 7.5 | Malus domestica |
General Information | Comment | Organism |
---|---|---|
evolution | DNA and amino acid sequence determination and analysis of LOX1 and LOX2 isozymes, phylogenetic analysis, only LOX1:Md:1a exhibits a glycine residue (Gly567) responsible for dual positional specificity and (R)-LOX activity | Malus domestica |
metabolism | the enzyme is involved in the LOX pathway, overview | Malus domestica |
additional information | structure homology modeling | Malus domestica |
physiological function | lipoxygenase (LOX) is an important contributor to the formation of aroma-active C6 aldehydes in apple (Malus3domestica) fruit upon tissue disruption, role in autonomously produced aroma volatiles from intact tissue, overview. The genetic association with a quantitative trait locus for fruit ester and the remarkable agreement in regio- and stereoselectivity of the LOX1:Md:1a reaction with the overall LOX activity found in mature apple fruits, suggest a major physiological function of LOX1:Md:1a during climacteric ripening of apples. While isozymes LOX1:Md:1c, LOX2:Md:2a, and LOX2:Md:2b may contribute to aldehyde production in immature fruit upon cell disruption isozyme, LOX1:Md:1a probably regulates the availability of precursors for ester production in intact fruit tissue. Both 9- and 13-hydroperoxides can be catabolized to aroma-active volatile aldehydes by hydroperoxide lyase. Only 13-LOX activity contributes to the apple aroma due to the formation of precursors of C6 volatile compounds. The dioxygenation of PUFAs by 9- and 13-LOX activity forms precursors for important phytooxylipins with functions in plant defense, wound signaling, senescence and fruit ripening | Malus domestica |