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Literature summary for 2.7.7.12 extracted from
- Galactose-1-phosphate uridylyltransferase: kinetics of formation and reaction of uridylyl-enzyme intermediate in wild-type and specifically mutated uridylyltransferases (2002), Methods Enzymol., 354, 134-148.
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| C160A | - |
Escherichia coli |
| Q168G | site-directed mutagenesis, reduced activity | Escherichia coli |
| Q168H | site-directed mutagenesis, reduced activity | Escherichia coli |
| Q168N | - |
Escherichia coli |
| Q168R | site-directed mutagenesis, 270000fold reduced activity compared to wild-type, i.e. nearly no remaining activity, mutant active sites can be uridylated by 65%, with very slow deuridylylation, compared to 100% for the wild-type, reduced metal content | Escherichia coli |
| Q168R | in humans galactosemia causing mutation, used as a model in bacterial system, 30000fold loss of activity, 28% reduced metal ion content | Escherichia coli |
| S161A | - |
Escherichia coli |
Inhibitors
| Inhibitors | Comment | Organism | Structure |
|---|---|---|---|
| D-galactose | galactosemia, disease caused by genetic disorder, is characterized by a galactose sensitivity | Homo sapiens |  |
KM Value [mM]
| KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| additional information | - |
additional information | - |
Homo sapiens | |
| additional information | - |
additional information | kinetics at 4°C, wild-type and mutants | Escherichia coli | |
| 0.072 | - |
UDP-glucose | recombinant mutant C160A, pH 8.5, 27°C | Escherichia coli | |
| 0.082 | - |
UDP-glucose | recombinant mutant C160A, pH 8.5, 27°C | Escherichia coli | |
| 0.125 | - |
alpha-D-galactose 1-phosphate | recombinant mutant C160A, pH 8.5, 27°C | Escherichia coli | |
| 0.2 | - |
UDP-glucose | - |
Homo sapiens | |
| 0.2 | - |
UDP-glucose | recombinant mutant Q168N, pH 8.5, 27°C | Escherichia coli | |
| 0.2 | - |
UDP-glucose | recombinant wild-type, pH 8.5, 27°C | Escherichia coli | |
| 0.223 | - |
alpha-D-galactose 1-phosphate | recombinant mutant S161A, pH 8.5, 27°C | Escherichia coli | |
| 0.3 | - |
alpha-D-galactose 1-phosphate | recombinant mutant Q168N, pH 8.5, 27°C | Escherichia coli | |
| 0.3 | - |
alpha-D-galactose 1-phosphate | recombinant wild-type, pH 8.5, 27°C | Escherichia coli | |
Metals/Ions
| Metals/Ions | Comment | Organism | Structure |
|---|---|---|---|
| Fe2+ | can be replaced by other metal ions | Escherichia coli | |
| Fe2+ | not essential | Escherichia coli | |
| Fe2+ | coordinated in a square pyramidal geometry with His296, His298, and Glu182 in a bidentate coordination providing the base ligands and His281 providing the axial ligand | Escherichia coli | |
| Zn2+ | required | Escherichia coli | |
| Zn2+ | can be replaced by other metal ions | Escherichia coli | |
| Zn2+ | coordinated in a tetrahedral geometry by Cys52, Cys55, His115, and His164 | Escherichia coli | |
Molecular Weight [Da]
| Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
|---|---|---|---|
| 79290 | - |
amino acid sequence determination | Escherichia coli |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| UDP-glucose + alpha-D-galactose 1-phosphate | Escherichia coli | - |
alpha-D-glucose 1-phosphate + UDP-galactose | - |
r | |
| UDP-glucose + alpha-D-galactose 1-phosphate | Homo sapiens | - |
alpha-D-glucose 1-phosphate + UDP-galactose | - |
r | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Escherichia coli | - |
- |
- |
| Homo sapiens | - |
- |
- |
Reaction
| Reaction | Comment | Organism | Reaction ID |
|---|---|---|---|
| UDP-alpha-D-glucose + alpha-D-galactose 1-phosphate = alpha-D-glucose 1-phosphate + UDP-alpha-D-galactose | Gln168 engages hydrogen bonding with the phosphoryl oxygen of the UMP moiety in the covalently formed reaction intermediate UMP-enzyme, UMP is bound to His166 | Escherichia coli | |
| UDP-alpha-D-glucose + alpha-D-galactose 1-phosphate = alpha-D-glucose 1-phosphate + UDP-alpha-D-galactose | ping pong bi bi kinetic model | Escherichia coli | |
| UDP-alpha-D-glucose + alpha-D-galactose 1-phosphate = alpha-D-glucose 1-phosphate + UDP-alpha-D-galactose | active site triad: His164, His165, and His166, with His166 as nulceophilic catalyst, highly conserved | Escherichia coli | |
| UDP-alpha-D-glucose + alpha-D-galactose 1-phosphate = alpha-D-glucose 1-phosphate + UDP-alpha-D-galactose | active site nucleophil H166 | Escherichia coli | |
| UDP-alpha-D-glucose + alpha-D-galactose 1-phosphate = alpha-D-glucose 1-phosphate + UDP-alpha-D-galactose | active site nucleophil H166 | Homo sapiens | |
| UDP-alpha-D-glucose + alpha-D-galactose 1-phosphate = alpha-D-glucose 1-phosphate + UDP-alpha-D-galactose | formation of a stable nucleotidylated histidine intermediate | Escherichia coli | |
| UDP-alpha-D-glucose + alpha-D-galactose 1-phosphate = alpha-D-glucose 1-phosphate + UDP-alpha-D-galactose | active site: C160SNPHP165 | Escherichia coli | |
| UDP-alpha-D-glucose + alpha-D-galactose 1-phosphate = alpha-D-glucose 1-phosphate + UDP-alpha-D-galactose | active site structure, enzyme complexed with UDP-galactose | Escherichia coli |
Specific Activity [micromol/min/mg]
| Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
|---|---|---|---|
| 0.00093 | - |
recombinant mutant S161A, cell extract | Escherichia coli |
| 0.023 | - |
purified recombinant mutant S161A | Escherichia coli |
| 0.1 | - |
recombinant mutant Q168G and Q168H, cell extract | Escherichia coli |
| 0.19 | - |
recombinant mutant Q168N, cell extract | Escherichia coli |
| 3.4 | - |
purified recombinant mutant Q168N | Escherichia coli |
| 9.9 | - |
recombinant mutant C160A, cell extract | Escherichia coli |
| 14.9 | - |
recombinant mutant C160S, cell extract | Escherichia coli |
| 16.3 | - |
recombinant wild-type, cell extract | Escherichia coli |
| 79.5 | - |
purified recombinant mutant C160A | Escherichia coli |
| 180 | - |
purified recombinant wild-type enzyme | Escherichia coli |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| UDP-glucose + alpha-D-galactose 1-phosphate | - |
Escherichia coli | alpha-D-glucose 1-phosphate + UDP-galactose | - |
r | |
| UDP-glucose + alpha-D-galactose 1-phosphate | - |
Homo sapiens | alpha-D-glucose 1-phosphate + UDP-galactose | - |
r | |
| UDP-glucose + alpha-D-galactose 1-phosphate | formation of a covalent uridylyl-enzyme intermediate, i.e. UMP-enzyme | Escherichia coli | alpha-D-glucose 1-phosphate + UDP-galactose | - |
r | |
| UDP-glucose + imidazole | wild-type, 800fold reduced activity compared to normal reaction intermediate uridylyl-enzyme as substrate, pH-dependent | Escherichia coli | uridine 5'-phosphoimidazole + alpha-D-glucose 1-phosphate | - |
r | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| More | - |
Homo sapiens |
| More | dimeric status is essential for activity | Escherichia coli |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| GALT | - |
Escherichia coli |
Turnover Number [1/s]
| Turnover Number Minimum [1/s] | Turnover Number Maximum [1/s] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| 0.0533 | - |
alpha-D-galactose 1-phosphate | recombinant mutant S161A, forward reaction, pH 8.5, 27°C | Escherichia coli | |
| 19 | - |
alpha-D-galactose 1-phosphate | recombinant mutant Q168N, forward reaction, pH 8.5, 27°C | Escherichia coli | |
| 265 | - |
alpha-D-galactose 1-phosphate | recombinant mutant C160A, forward reaction, pH 8.5, 27°C | Escherichia coli | |
| 780 | - |
alpha-D-galactose 1-phosphate | recombinant wild-type, forward reaction, pH 8.5, 27°C | Escherichia coli | |
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