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Literature summary extracted from

  • Mitschke, L.; Parthier, C.; Schroeder-Tittmann, K.; Coy, J.; Luedtke, S.; Tittmann, K.
    The crystal structure of human transketolase and new insights into its mode of action (2010), J. Biol. Chem., 285, 31559-31570.
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

EC Number Cloned (Comment) Organism
2.2.1.1 expression in Escherichia coli Homo sapiens

Crystallization (Commentary)

EC Number Crystallization (Comment) Organism
2.2.1.1 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]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
2.2.1.1 0.255
-
 D-xylulose 5-phosphate recombinant enzyme, pH 7.6, 30°C Homo sapiens
2.2.1.1 0.303
-
 D-xylulose 5-phosphate His-tagged recombinant enzyme, pH 7.6, 30°C Homo sapiens
2.2.1.1 0.48
-
 D-ribose 5-phosphate recombinant enzyme, pH 7.6, 30°C Homo sapiens
2.2.1.1 0.61
-
 D-ribose 5-phosphate His-tagged recombinant enzyme, pH 7.6, 30°C Homo sapiens

Organism

EC Number Organism UniProt Comment Textmining
2.2.1.1 Homo sapiens P29401
-
-

Reaction

EC Number Reaction Comment Organism Reaction ID
2.2.1.1 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
a

Specific Activity [micromol/min/mg]

EC Number Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
2.2.1.1 2.7
-
 His-tagged recombinant enzyme, pH 7.6, 30°C Homo sapiens
2.2.1.1 5.5
-
 recombinant enzyme, pH 7.6, 30°C Homo sapiens

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2.2.1.1 D-xylulose 5-phosphate + D-ribose 5-phosphate
-
 Homo sapiens sedoheptulose 7-phosphate + D-glyceraldehyde 3-phosphate
-
 ?

Synonyms

EC Number Synonyms Comment Organism
2.2.1.1 TKT
-
 Homo sapiens

Turnover Number [1/s]

EC Number Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
2.2.1.1 3.1
-
 D-xylulose 5-phosphate His-tagged recombinant enzyme, pH 7.6, 30°C Homo sapiens
2.2.1.1 6.3
-
 D-xylulose 5-phosphate recombinant enzyme, pH 7.6, 30°C Homo sapiens

Cofactor

EC Number Cofactor Comment Organism Structure
2.2.1.1 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