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Literature summary for 2.7.1.1 extracted from
- Differences in substrate specificity and kinetic properties of the recombinant hexokinases HXK1 and HXK2 from Entamoeba histolytica (2000), Mol. Biochem. Parasitol., 105, 71-80.
Activating Compound
| Activating Compound | Comment | Organism | Structure |
|---|---|---|---|
| glucose 6-phosphate | recombinant HXK1: at 10 mM 13% activation, at 20 mM 31% activation, recombinant HXK2: at 10 mM 23% activation, at 20 mM 48% activation | Entamoeba histolytica |  |
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| cDNAs coding for HXK1 and HXK2 are cloned and expressed in Escherichia coli K38 | Entamoeba histolytica |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| additional information | HXK1 mutants with modified active sites | Entamoeba histolytica |
Inhibitors
| Inhibitors | Comment | Organism | Structure |
|---|---|---|---|
| adenosine | at 10 mM, recombinant HXK1: 36% inhibition, recombinant HXK2: 5% inhibition | Entamoeba histolytica | |
| ADP | strong, recombinant HXK1 and 2, HXK1 is more sensitive to inhibition than HXK2 | Entamoeba histolytica | |
| AMP | strong, recombinant HXK1 and 2, HXK1 is more sensitive to inhibition than HXK2 | Entamoeba histolytica | |
| additional information | not inhibited by D-glucose 6-phosphate | Entamoeba histolytica |
KM Value [mM]
| KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| additional information | - |
additional information | of HXK1 mutants with modified active site | Entamoeba histolytica | |
| 0.047 | - |
D-glucose | recombinant HXK2, at 30°C, pH 8 | Entamoeba histolytica | |
| 0.059 | - |
D-glucose | recombinant HXK1, at 30°C, pH 8 | Entamoeba histolytica | |
| 0.183 | - |
ATP | recombinant HXK1, at 30°C, pH 8 | Entamoeba histolytica | |
| 0.654 | - |
ATP | recombinant HXK2, at 30°C, pH 8 | Entamoeba histolytica | |
| 1.03 | - |
D-mannose | recombinant HXK1, at 30°C, pH 8 | Entamoeba histolytica | |
| 2 | - |
D-mannose | recombinant HXK2, at 30°C, pH 8 | Entamoeba histolytica | |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| D-glucose + ATP | Entamoeba histolytica | initial enzyme of glycolysis | D-glucose 6-phosphate + ADP | - |
? | |
| D-glucose + ATP | Entamoeba histolytica | at high energy charge HXK1 may be involved in glycolysis and in some biosynthetic processes, e.g. phosphorylating mannose or glucose for the later integration into membrane components, at low energy charge HXK1 could be inhibited by AMP and ADP, and HXK2 would be more active and could keep up glucokinase activity for glycolysis | D-glucose 6-phosphate + ADP | - |
? | |
| D-glucose + ATP | Entamoeba histolytica SFL-3 | initial enzyme of glycolysis | D-glucose 6-phosphate + ADP | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Entamoeba histolytica | - |
2 isoenzymes: HXK1 and HXK2 | - |
| Entamoeba histolytica SFL-3 | - |
2 isoenzymes: HXK1 and HXK2 | - |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| recombinant HXK1 and HXK2, expressed in Escherichia coli K38 | Entamoeba histolytica |
Specific Activity [micromol/min/mg]
| Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
|---|---|---|---|
| additional information | - |
- |
Entamoeba histolytica |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| D-glucose + ATP | good substrate | Entamoeba histolytica | ADP + D-glucose 6-phosphate | - |
? | |
| D-glucose + ATP | good substrate | Entamoeba histolytica SFL-3 | ADP + D-glucose 6-phosphate | - |
? | |
| D-glucose + ATP | initial enzyme of glycolysis | Entamoeba histolytica | D-glucose 6-phosphate + ADP | - |
? | |
| D-glucose + ATP | at high energy charge HXK1 may be involved in glycolysis and in some biosynthetic processes, e.g. phosphorylating mannose or glucose for the later integration into membrane components, at low energy charge HXK1 could be inhibited by AMP and ADP, and HXK2 would be more active and could keep up glucokinase activity for glycolysis | Entamoeba histolytica | D-glucose 6-phosphate + ADP | - |
? | |
| D-glucose + ATP | initial enzyme of glycolysis | Entamoeba histolytica SFL-3 | D-glucose 6-phosphate + ADP | - |
? | |
| D-mannose + ATP | HXK1: good substrate, HXK2: much lower phosphorylation rate than of HXK1 | Entamoeba histolytica | ADP + D-mannose 6-phosphate | - |
? | |
| D-mannose + ATP | HXK1: good substrate, HXK2: much lower phosphorylation rate than of HXK1 | Entamoeba histolytica SFL-3 | ADP + D-mannose 6-phosphate | - |
? | |
| additional information | not: fructose | Entamoeba histolytica | ? | - |
? | |
| additional information | not: D-galactose | Entamoeba histolytica | ? | - |
? | |
| additional information | not: fructose | Entamoeba histolytica SFL-3 | ? | - |
? | |
| additional information | not: D-galactose | Entamoeba histolytica SFL-3 | ? | - |
? | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| ? | x * about 50000, HXK1 and 2 | Entamoeba histolytica |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 30 | - |
assay at | Entamoeba histolytica |
| 45 | - |
recombinant HXK1 and 2 | Entamoeba histolytica |
Temperature Range [°C]
| Temperature Minimum [°C] | Temperature Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 25 | - |
HXK1: 40% of maximum activity, HXK2: 28% of maximum activity | Entamoeba histolytica |
| 37 | - |
HXK1: 78% of maximum activity, HXK2: 69% of maximum activity | Entamoeba histolytica |
Turnover Number [1/s]
| Turnover Number Minimum [1/s] | Turnover Number Maximum [1/s] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| 195 | - |
D-glucose | recombinant HXK2, at 30°C, pH 8 | Entamoeba histolytica | |
| 284 | - |
D-glucose | recombinant HXK1, at 30°C, pH 8 | Entamoeba histolytica | |
pH Optimum
| pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|
| 8 | - |
assay at | Entamoeba histolytica |
| 8 | 9 | recombinant HXK1 and 2: maximum activity, HXK1 is clearly more active than HXK2 around pH 6-7.5 | Entamoeba histolytica |
pH Range
| pH Minimum | pH Maximum | Comment | Organism |
|---|---|---|---|
| 6 | 9 | recombinant HXK1 and 2, significant activity between the range | Entamoeba histolytica |
pH Stability
| pH Stability | pH Stability Maximum | Comment | Organism |
|---|---|---|---|
| 4 | - |
recombinant HXK1 and 2 precipitate and lose all activity | Entamoeba histolytica |
Cofactor
| Cofactor | Comment | Organism | Structure |
|---|---|---|---|
| ATP | - |
Entamoeba histolytica | |
Ki Value [mM]
| Ki Value [mM] | Ki Value maximum [mM] | Inhibitor | Comment | Organism | Structure |
|---|---|---|---|---|---|
| 0.00065 | - |
AMP | recombinant HXK1, at 30°C, pH 8 | Entamoeba histolytica | |
| 0.031 | - |
AMP | recombinant HXK2, at 30°C, pH 8 | Entamoeba histolytica | |
| 0.036 | - |
ADP | recombinant HXK1, at 30°C, pH 8 | Entamoeba histolytica | |
| 0.193 | - |
ADP | recombinant HXK2, at 30°C, pH 8 | Entamoeba histolytica | |
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