Cloned (Comment) | Organism |
---|---|
gene VDE1, recombinant expression of wild-type and truncated mutants in Escherichia coli strain BL21(DE3) in inclusion bodies | Spinacia oleracea |
Protein Variants | Comment | Organism |
---|---|---|
additional information | the C-terminally truncated VDE does not show such an oligomerization, is relatively more active at higher pH, but does not alter the KM for ascorbate | Spinacia oleracea |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
chloroplast thylakoid lumen | - |
Spinacia oleracea | 9543 | - |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
violaxanthin + 2 L-ascorbate | Spinacia oleracea | overall reaction | zeaxanthin + 2 L-dehydroascorbate + 2 H2O | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Spinacia oleracea | Q9SM43 | - |
- |
Purification (Comment) | Organism |
---|---|
recombinant enzyme from Escherichia coli strain BL21(DE3) solubilized from inclusion bodies | Spinacia oleracea |
Renatured (Comment) | Organism |
---|---|
recombinant enzyme from Escherichia coli strain BL21(DE3) inclusion bodies by solibilization with 8 M urea, 60 mM Tris-HCl, pH 8.0, 60 mM NaCl, and 0.6 mM EDTA, followed by dialysis and ultracentrifugation | Spinacia oleracea |
Source Tissue | Comment | Organism | Textmining |
---|---|---|---|
leaf | - |
Spinacia oleracea | - |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
additional information | by measuring the initial formation of the product, enzyme VDE is found to convert a large number of violaxanthin molecules to antheraxanthin before producing any zeaxanthin, favoring a model where violaxanthin is bound non-symmetrically in VDE, overview | Spinacia oleracea | ? | - |
? | |
violaxanthin + 2 L-ascorbate | overall reaction | Spinacia oleracea | zeaxanthin + 2 L-dehydroascorbate + 2 H2O | - |
? |
Subunits | Comment | Organism |
---|---|---|
? | x * 43000, recombinant wild-type enzyme, SDS-PAGE | Spinacia oleracea |
More | enzyme VDE consists of three domains with the central lipocalin-like domain. VDE enzyme activity is possible without the C-terminal domain but not without the N-terminal domain. The N-terminal domain shows no VDE activity by itself, but when separately expressed domains are mixed, VDE activity is possible. Presence of alpha-helical structure in both the N- and C-terminal domains | Spinacia oleracea |
Synonyms | Comment | Organism |
---|---|---|
VDE | - |
Spinacia oleracea |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
22 | - |
assay at | Spinacia oleracea |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
5.2 | - |
assay at | Spinacia oleracea |
pH Minimum | pH Maximum | Comment | Organism |
---|---|---|---|
additional information | - |
an increase of the hydrodynamic radius of wild-type VDE is observed when pH is lowered toward the pH required for activity, consistent with a pH-dependent oligomerization | Spinacia oleracea |
pH Stability | pH Stability Maximum | Comment | Organism |
---|---|---|---|
additional information | - |
an increase of the hydrodynamic radius of wild-type VDE is observed when pH is lowered toward the pH required for activity, consistent with a pH-dependent oligomerization | Spinacia oleracea |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
L-ascorbate | - |
Spinacia oleracea |
Organism | Comment | pI Value Maximum | pI Value |
---|---|---|---|
Spinacia oleracea | recombinant N-terminally truncated enzyme mutant, isoelectric focusing | - |
4.79 |
Spinacia oleracea | recombinant wild-type enzyme, isoelectric focusing | - |
4.83 |
Spinacia oleracea | recombinant N-terminal domain, isoelectric focusing | - |
5.04 |
Spinacia oleracea | recombinant mix of N-terminal and C-terminal domain, isoelectric focusing | - |
5.24 |
Spinacia oleracea | recombinant C-terminally truncated enzyme mutant, isoelectric focusing | - |
5.36 |
General Information | Comment | Organism |
---|---|---|
additional information | VDE enzyme activity is possible without the C-terminal domain but not without the N-terminal domain. The N-terminal domain shows no VDE activity by itself, but when separately expressed domains are mixed, VDE activity is possible | Spinacia oleracea |
physiological function | photosynthetic organisms need protection against excessive light. By using non-photochemical quenching, where the excess light is converted into heat, the organism can survive at higher light intensities. This process is partly initiated by the formation of zeaxanthin, which is achieved by the de-epoxidation of violaxanthin and antheraxanthin to zeaxanthin. This reaction is catalyzed by violaxanthin de-epoxidase (VDE) | Spinacia oleracea |