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Literature summary extracted from
- L-gulono-gamma-lactone oxidase expression and vitamin C synthesis in the brain and kidney of the African lungfish, Protopterus annectens (2014), FASEB J., 28, 3506-3517 .
Cloned(Commentary)
| EC Number | Cloned (Comment) | Organism |
|---|---|---|
| 1.1.3.8 | gene gulo, cloned from kidney, DNA and amino acid sequence determination and analysis, phylogenetic analysis, quantitative real-time PCR expression analysis | Protopterus annectens |
Localization
| EC Number | Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|---|
| 1.1.3.8 | microsome | - |
Protopterus annectens | - |
- |
Natural Substrates/ Products (Substrates)
| EC Number | Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|---|
| 1.1.3.8 | L-gulono-1,4-lactone + O2 | Protopterus annectens | during the catalytic reaction by Gulo, flavin accepts 2 electrons from the substrate l-gulono-gamma-lactone, thus undergoing a reduction, followed by oxidation through molecular oxygen, with the reaction presumably involving the ALO domain. Through this process, 2-oxo-l-gulono-gamma-lactone and hydrogen peroxide are produced, and L-ascorbic acid is formed by nonenzymatic isomerisation of the former product | L-ascorbate + H2O2 | - |
? |  |
Organism
| EC Number | Organism | UniProt | Comment | Textmining |
|---|---|---|---|---|
| 1.1.3.8 | no activity in Homo sapiens | - |
- |
- |
| 1.1.3.8 | Protopterus annectens | A0A067XNL8 | - |
- |
Source Tissue
| EC Number | Source Tissue | Comment | Organism | Textmining |
|---|---|---|---|---|
| 1.1.3.8 | brain | no significant changes in mRNA expression levels and protein abundances of gulo/Gulo in the brain during estivation and arousal, overview | Protopterus annectens | - |
| 1.1.3.8 | kidney | high expression level, reducing effects of estivation on gulo/Gulo expression in the kidney, overview | Protopterus annectens | - |
| 1.1.3.8 | additional information | Gulo activity from the kidney is 32fold higher than that from the brain. No enzyme expression in liver, quantitative enzyme expression analysis in brain and kidney during estivation compared to non-estivation periods, overview | Protopterus annectens | - |
Substrates and Products (Substrate)
| EC Number | Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|---|
| 1.1.3.8 | L-gulono-1,4-lactone + O2 | during the catalytic reaction by Gulo, flavin accepts 2 electrons from the substrate l-gulono-gamma-lactone, thus undergoing a reduction, followed by oxidation through molecular oxygen, with the reaction presumably involving the ALO domain. Through this process, 2-oxo-l-gulono-gamma-lactone and hydrogen peroxide are produced, and L-ascorbic acid is formed by nonenzymatic isomerisation of the former product | Protopterus annectens | L-ascorbate + H2O2 | - |
? | |
Subunits
| EC Number | Subunits | Comment | Organism |
|---|---|---|---|
| 1.1.3.8 | ? | x * 51400, about, sequence calculation | Protopterus annectens |
| 1.1.3.8 | More | the two main domains in the Gulo protein include the flavin adenine dinucleotide (FAD) binding domain, aa 21-155, and the D-arabinono-1,4-lactone oxidase (ALO) activity domain, aa 180-350 | Protopterus annectens |
Synonyms
| EC Number | Synonyms | Comment | Organism |
|---|---|---|---|
| 1.1.3.8 | GULO | - |
Protopterus annectens |
| 1.1.3.8 | L-gulono-gamma-lactone oxidase | - |
Protopterus annectens |
Cofactor
| EC Number | Cofactor | Comment | Organism | Structure |
|---|---|---|---|---|
| 1.1.3.8 | FAD | the flavin adenine dinucleotide (FAD) binding domain comprises amino acids 21-155. FAD binds to the FAD binding domain via an 8-alpha-(N3-histidyl)-riboflavin linkage at the conserved histidine residue at position 54. During the catalytic reaction by Gulo, flavin accepts 2 electrons from the substrate l-gulono-gamma-lactone, thus undergoing a reduction, followed by oxidation through molecular oxygen, with the reaction presumably involving the ALO domain | Protopterus annectens | |
Expression
| EC Number | Organism | Comment | Expression |
|---|---|---|---|
| 1.1.3.8 | Protopterus annectens | drastic decreases in gulo mRNA expression as well as Gulo protein abundance in the kidney after 6 months of estivation | down |
| 1.1.3.8 | Protopterus annectens | no significant changes in mRNA expression levels and protein abundances of gulo/Gulo in the brain during estivation and arousal, overview | additional information |
General Information
| EC Number | General Information | Comment | Organism |
|---|---|---|---|
| 1.1.3.8 | metabolism | the enzyme catalyzes the last step of L-ascorbate biosynthesis | Protopterus annectens |
| 1.1.3.8 | physiological function | GULO is a microsomal enzyme that catalyzes the aerobic conversion of gulonolactone to ascorbate, with the production of hydrogen peroxide. Desiccation induces Protopterus annectens to estivate, and six months of estivation lead to drastic decreases in gulo/Gulo expression and ascorbate concentration in the kidney. But high concentrations of ascorbate and ascorbate/dehydroascorbate are maintained in the brain during estivation, probably resulting from in situ ascorbate synthesis. The ability to synthesize ascorbate to ameliorate oxidative stress directly in the brain might contribute to the ability of the fish to undergo prolonged estivation on land. Ascorbate might act as an antistress agent since estivation can be a stressful event to the brain. For instance, ammonia excretion is impeded during the induction and maintenance phases of estivation due to a lack of water | Protopterus annectens |
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