Cloned (Comment) | Organism |
---|---|
expression in Escherichia coli | Homo sapiens |
Crystallization (Comment) | Organism |
---|---|
to 1.75 A resolution, space group C2 with one monomer in the asymmetric unit. Two monomers form the homodimeric biological assembly with two identical active sites at the dimer interface. The protomer exhibits the typical three alpha/beta-domain structure and topology reported for transketolases from other species, with structural differences for several loop regions and the linker that connects the diphosphate and pyridine domain. Two lysines and a serine interact with the beta-phosphate of thiamine diphosphate. Residue Gln189 spans over the thiazolium moiety of thiamine diphosphate and replaces an isoleucine found in most non-mammalian transketolases. The side chain of Gln428 forms a hydrogen bond with the 4-amino group of thiamine diphosphate and replaces a histidine that is invariant in all nonmammalian transketolases. All other amino acids involved in substrate binding and catalysis are strictly conserved. Formation of the central 1,2-dihydroxyethyl-thiamine diphosphate carbanion-enamine intermediate is thermodynamically favored with increasing carbon chain length of the donor ketose substrate | Homo sapiens |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.255 | - |
D-xylulose 5-phosphate | recombinant enzyme, pH 7.6, 30°C | Homo sapiens | |
0.303 | - |
D-xylulose 5-phosphate | His-tagged recombinant enzyme, pH 7.6, 30°C | Homo sapiens | |
0.48 | - |
D-ribose 5-phosphate | recombinant enzyme, pH 7.6, 30°C | Homo sapiens | |
0.61 | - |
D-ribose 5-phosphate | His-tagged recombinant enzyme, pH 7.6, 30°C | Homo sapiens |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Homo sapiens | P29401 | - |
- |
Reaction | Comment | Organism | Reaction ID |
---|---|---|---|
sedoheptulose 7-phosphate + D-glyceraldehyde 3-phosphate = D-ribose 5-phosphate + D-xylulose 5-phosphate | formation of the central 1,2-dihydroxyethyl-thiamine diphosphate carbanion-enamine intermediate is thermodynamically favored with increasing carbon chain length of the donor ketose substrate | Homo sapiens |
Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
---|---|---|---|
2.7 | - |
His-tagged recombinant enzyme, pH 7.6, 30°C | Homo sapiens |
5.5 | - |
recombinant enzyme, pH 7.6, 30°C | Homo sapiens |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
D-xylulose 5-phosphate + D-ribose 5-phosphate | - |
Homo sapiens | sedoheptulose 7-phosphate + D-glyceraldehyde 3-phosphate | - |
? |
Synonyms | Comment | Organism |
---|---|---|
TKT | - |
Homo sapiens |
Turnover Number Minimum [1/s] | Turnover Number Maximum [1/s] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
3.1 | - |
D-xylulose 5-phosphate | His-tagged recombinant enzyme, pH 7.6, 30°C | Homo sapiens | |
6.3 | - |
D-xylulose 5-phosphate | recombinant enzyme, pH 7.6, 30°C | Homo sapiens |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
thiamine diphosphate | two lysine residues and a serine interact with the beta-phosphate of thiamine diphosphate. Residue Gln189 spans over the thiazolium moiety of thiamine diphosphate | Homo sapiens |