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Literature summary for 5.1.99.7 extracted from
- Biosynthesis of pteridines in Escherichia coli. Structural and mechanistic similarity of dihydroneopterin-triphosphate epimerase and dihydroneopterin aldolase (1998), J. Biol. Chem., 273, 17418-17424.
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| gene folX, recombinant expression in Escherichia coli strain M15 | Escherichia coli |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| additional information | generation of a folX knockout mutant from strain SK6600 | Escherichia coli |
Inhibitors
| Inhibitors | Comment | Organism | Structure |
|---|---|---|---|
| potassium iodide | - |
Escherichia coli |  |
KM Value [mM]
| KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| additional information | - |
additional information | steady-state kinetic analysis, overview | Escherichia coli | |
| 0.013 | - |
7,8-dihydroneopterin 3'-triphosphate | pH 6.2, 37°C, recombinant enzyme | Escherichia coli | |
| 0.066 | - |
7,8-dihydromonapterin | pH 6.2, 37°C, recombinant enzyme | Escherichia coli | |
| 0.149 | - |
7,8-dihydroneopterin | pH 6.2, 37°C, recombinant enzyme | Escherichia coli | |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| 7,8-dihydroneopterin 3'-triphosphate | Escherichia coli | - |
7,8-dihydromonapterin 3'-triphosphate | - |
r | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Escherichia coli | - |
gene folX | - |
| Escherichia coli XL1-Blue | - |
gene folX | - |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| recombinant enzyme 2.7fold from Escherichia coli strain M15 by anion exchange chromatography, ultrafiltration, heat treatment at 80°C for 4 min, and gel filtration | Escherichia coli |
Reaction
| Reaction | Comment | Organism | Reaction ID |
|---|---|---|---|
| 7,8-dihydroneopterin 3'-triphosphate = 7,8-dihydromonapterin 3'-triphosphate | reaction mechanism of the epimerase, overview. The reaction can be initiated by protonation of N-5 followed by deprotonation at the acidic C-19 of dihydroneopterin- or dihydromonapterin-type substrates. Epimerization at C-2 might result from reversal of the cleavage reaction without stereochemical control | Escherichia coli |
Specific Activity [micromol/min/mg]
| Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
|---|---|---|---|
| 7.68 | - |
purified recombinant enzyme, pH 6.2, 55°C | Escherichia coli |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| 7,8-dihydromonapterin | - |
Escherichia coli | 7,8-dihydroneopterin | - |
r | |
| 7,8-dihydroneopterin | - |
Escherichia coli | 7,8-dihydromonapterin | - |
r | |
| 7,8-dihydroneopterin 3'-triphosphate | - |
Escherichia coli | 7,8-dihydromonapterin 3'-triphosphate | - |
r | |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| dihydroneopterin-triphosphate epimerase | - |
Escherichia coli |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 37 | 55 | - |
Escherichia coli |
pH Optimum
| pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|
| 6.2 | - |
assay at | Escherichia coli |
General Information
| General Information | Comment | Organism |
|---|---|---|
| malfunction | a gene folX deletion mutant shows normal growth properties on complete medium as well as on minimal medium | Escherichia coli |
| metabolism | enzymes, encoded by genes folX and folB, are involved in the tetrahydrofolate biosynthesis. The aldolase can use L-threo-dihydroneopterin and D-erythro-dihydroneopterin as substrates for the formation of 6-hydroxymethyldihydropterin, but it can also catalyze the epimerization of carbon 2' of dihydroneopterin and dihydromonapterinat appreciable velocity. The epimerase catalyzes the epimerization of carbon 2' in the triphosphates of dihydroneopterin and dihydromonapterin. The enzyme can also catalyze the cleavage of the position 6 side chain of several pteridine derivatives at a slow rate. The polarization of the 2'-hydroxy group of the substrate can serve as the initial reaction step for the aldolase as well as for the epimerase activity. Epimerase- as well as aldolase-type reactions can be catalyzed by both the FolB and FolX proteins | Escherichia coli |
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