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Literature summary for 4.2.1.114 extracted from
- Methanogen homoaconitase catalyzes both hydrolyase reactions in coenzyme B biosynthesis (2008), J. Biol. Chem., 283, 28888-28896.
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| DNA and amino acid sequence determination and analysis, coexpression of MJ1003 and MJ1271 proteins in Escherichia coli strain BL21(DE3) | Methanocaldococcus jannaschii |
Inhibitors
| Inhibitors | Comment | Organism | Structure |
|---|---|---|---|
| (S)-homocitrate | complete inhibition at 0.1 mM | Methanocaldococcus jannaschii |  |
| cis-aconitate | 50% inhibition of the hydrolase activity at 0.025 mM | Methanocaldococcus jannaschii | |
| cis-homoaconitate/(R)-homocitrate | mixtures of 0.1 mM cis-homoaconitate and 0.05 mM (R)-homocitrate reduce the HACN hydrolyase activity by 50% | Methanocaldococcus jannaschii | |
| additional information | no inhibition by citraconate up to 0.2 mM | Methanocaldococcus jannaschii | |
| trans-(homo)3aconitate | 50% inhibition of the hydrolase activity at 0.4 mM | Methanocaldococcus jannaschii | |
| trans-aconitate | 50% inhibition of the hydrolase activity at 0.1 mM | Methanocaldococcus jannaschii | |
KM Value [mM]
| KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| additional information | - |
additional information | steady-state kinetics | Methanocaldococcus jannaschii | |
| 0.022 | - |
cis-homoaconitate | pH 9.0, 60°C, recombinant enzyme, hydrolase reaction | Methanocaldococcus jannaschii | |
| 0.03 | - |
cis-homo2aconitate | pH 9.0, 60°C, recombinant enzyme, hydrolase reaction | Methanocaldococcus jannaschii | |
| 0.036 | - |
cis-homo3aconitate | pH 9.0, 60°C, recombinant enzyme, hydrolase reaction | Methanocaldococcus jannaschii | |
| 0.175 | - |
cis-homo4aconitate | pH 9.0, 60°C, recombinant enzyme, hydrolase reaction | Methanocaldococcus jannaschii | |
| 0.33 | - |
Maleate | pH 9.0, 60°C, recombinant enzyme, hydrolase reaction | Methanocaldococcus jannaschii | |
| 1.5 | - |
(R)-homocitrate | pH 8.5, 60°C, recombinant enzyme, dehydratase reaction | Methanocaldococcus jannaschii | |
Metals/Ions
| Metals/Ions | Comment | Organism | Structure |
|---|---|---|---|
| Fe2+ | the enzyme contains an iron-sulfur center, reconstitution of the purified recombinant apoenzyme with iron-sulfur, overview | Methanocaldococcus jannaschii | |
| Mg2+ | required for the hydratase reaction, not for the hydrolase reaction | Methanocaldococcus jannaschii | |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| cis-(homo)2aconitate + H2O | Methanocaldococcus jannaschii | - |
(-)-threo-iso(homo)2citrate | - |
? | |
| cis-(homo)3aconitate + H2O | Methanocaldococcus jannaschii | - |
(-)-threo-iso(homo)3citrate | - |
? | |
| additional information | Methanocaldococcus jannaschii | homoaconitase enzymes catalyze hydrolyase reactions in the alpha-aminoadipate pathway for lysine biosynthesis or the 2-oxosuberate pathway for methanogenic coenzyme B biosynthesis | ? | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Methanocaldococcus jannaschii | - |
- |
- |
| Methanocaldococcus jannaschii | Q58991 | the sequence contains the alteration C229A resulting in Q77K amino acid exchange compared to the MJ1596 sequence reported by the genome sequencing project, cf. EC 1.1.1.87; proteins MJ1003 and MJ1271 | - |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| recombinant MJ1003 and MJ1271 proteins from Escherichia coli strain BL21(DE3) by heat treatment of the cell lysate, followed by anion exchange chromatography, dialysis, and ultrafiltration | Methanocaldococcus jannaschii |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| (R)-2-hydroxybutane-1,2,4-tricarboxylate | i.e. (R)-homocitrate, overall reaction, the enzyme catalyzes both the dehydration of (R)-homocitrate to form cis-homoaconitate, and hydration producing homoisocitrate | Methanocaldococcus jannaschii | (1R,2S)-1-hydroxybutane-1,2,4-tricarboxylate | i.e. homoisocitrate | r | |
| (R)-2-hydroxybutane-1,2,4-tricarboxylate | i.e. (R)-homocitrate, first half-reaction | Methanocaldococcus jannaschii | (Z)-but-1-ene-1,2,4-tricarboxylate + H2O | i.e. cis-homoaconitate, the activity in the reverse direction is similar as with (R)-homocitrate | r | |
| (Z)-but-1-ene-1,2,4-tricarboxylate + H2O | second half-reaction | Methanocaldococcus jannaschii | (1R,2S)-1-hydroxybutane-1,2,4-tricarboxylate | i.e. homoisocitrate | r | |
| cis-(homo)2aconitate + H2O | the activity is similar as with (R)-homocitrate | Methanocaldococcus jannaschii | ? | - |
? | |
| cis-(homo)2aconitate + H2O | - |
Methanocaldococcus jannaschii | (-)-threo-iso(homo)2citrate | - |
? | |
| cis-(homo)3aconitate + H2O | the activity is similar as with (R)-homocitrate | Methanocaldococcus jannaschii | ? | - |
? | |
| cis-(homo)3aconitate + H2O | - |
Methanocaldococcus jannaschii | (-)-threo-iso(homo)3citrate | - |
? | |
| cis-(homo)4aconitate + H2O | the activity is similar as with (R)-homocitrate | Methanocaldococcus jannaschii | ? | - |
? | |
| maleate + H2O | - |
Methanocaldococcus jannaschii | ? | - |
? | |
| additional information | homoaconitase enzymes catalyze hydrolyase reactions in the alpha-aminoadipate pathway for lysine biosynthesis or the 2-oxosuberate pathway for methanogenic coenzyme B biosynthesis | Methanocaldococcus jannaschii | ? | - |
? | |
| additional information | homoaconitase together with the endogenous homoisocitrate dehydrogenase, EC 1.1.1.87, catalyze all of the isomerization and oxidative decarboxylation reactions required to form 2-oxoadipate, 2-oxopimelate, and 2-oxosuberate, completing three iterations of the 2-oxoacid elongation pathway. Methanogenic archaeal homoaconitases and fungal homoaconitases evolved in parallel in the aconitase superfamily, LC-MS analysis of enzyme reaction products, overview | Methanocaldococcus jannaschii | ? | - |
? | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| tetramer | heterotetramer, MJ1003 and MJ1271 proteins form an active homoaconitase enzyme | Methanocaldococcus jannaschii |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| HACN | - |
Methanocaldococcus jannaschii |
| Homoaconitase | - |
Methanocaldococcus jannaschii |
| More | the enzyme belongs to the aconitase superfamily | Methanocaldococcus jannaschii |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 60 | - |
hydrolase and hydratase assay at | Methanocaldococcus jannaschii |
Turnover Number [1/s]
| Turnover Number Minimum [1/s] | Turnover Number Maximum [1/s] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| 0.37 | - |
(R)-homocitrate | pH 8.5, 60°C, recombinant enzyme, dehydratase reaction | Methanocaldococcus jannaschii | |
| 0.66 | - |
cis-homo2aconitate | pH 9.0, 60°C, recombinant enzyme, hydrolase reaction | Methanocaldococcus jannaschii | |
| 0.75 | - |
cis-homoaconitate | pH 9.0, 60°C, recombinant enzyme, hydrolase reaction | Methanocaldococcus jannaschii | |
| 2.5 | - |
cis-homo3aconitate | pH 9.0, 60°C, recombinant enzyme, hydrolase reaction | Methanocaldococcus jannaschii | |
| 5.6 | - |
cis-homo4aconitate | pH 9.0, 60°C, recombinant enzyme, hydrolase reaction | Methanocaldococcus jannaschii | |
| 6 | - |
Maleate | pH 9.0, 60°C, recombinant enzyme, hydrolase reaction | Methanocaldococcus jannaschii | |
pH Optimum
| pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|
| 8.5 | - |
hydratase assay at | Methanocaldococcus jannaschii |
| 9 | - |
hydrolase assay at | Methanocaldococcus jannaschii |
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