Literature summary extracted from

Yurshev, V.A.; Sevostyanova, I.A.; Solovjeva, O.N.; Zabrodskaya, S.V.; Kochetov, G.A.
Nonequivalence of transketolase active centers with respect to acceptor substrate binding (2007), Biochem. Biophys. Res. Commun., 361, 1044-1047.

Activating Compound

EC Number	Activating Compound	Comment	Organism	Structure
2.2.1.1	additional information	active centers of the enzyme are functionally nonequivalent with respect to ribose 5-phosphate binding	Saccharomyces cerevisiae

KM Value [mM]

EC Number	KM Value [mM]	KM Value Maximum [mM]	Substrate	Comment	Organism	Structure
2.2.1.1	0.06	-	D-ribose 5-phosphate	first active center of transketolase	Saccharomyces cerevisiae
2.2.1.1	0.06	-	D-ribose 5-phosphate	pH 7.6, 25°C, affinity to the first active center when the second center is unoccupied	Saccharomyces cerevisiae
2.2.1.1	0.08	-	D-ribose 5-phosphate	hemiholotransketolase 2, i.e., transketolase, in which the functional active center has a lower affinity for thiamine diphosphate than hemiholotransketolase 1	Saccharomyces cerevisiae
2.2.1.1	0.09	-	D-ribose 5-phosphate	hemiholotransketolase 1, i. e. transketolase, in which the functional active center has a higher affinity for the coenzyme than the other active center	Saccharomyces cerevisiae
2.2.1.1	0.25	-	D-ribose 5-phosphate	second active center of transketolase	Saccharomyces cerevisiae
2.2.1.1	0.25	-	D-ribose 5-phosphate	pH 7.6, 25°C, affinity to the second active center when the first center is occupied	Saccharomyces cerevisiae

Organism

EC Number	Organism	UniProt	Comment	Textmining
2.2.1.1	Saccharomyces cerevisiae	-	-	-

Purification (Commentary)

EC Number	Purification (Comment)	Organism
2.2.1.1	to homogeneity	Saccharomyces cerevisiae

Renatured (Commentary)

EC Number	Renatured (Comment)	Organism
2.2.1.1	hemiholotransketolase 1 is the enzyme in which the only functional active center is the one exhibiting higher affinity for thiamine diphosphate. In the presence of Ca2+, the active centers of transketolase differ in their affinity for thiamine diphosphate by approximately one order of magnitude. When adding an equimolar amount of thiamine diphosphate to apotransketolase, it becomes completely bound to the 1 active center and is not dissociated from it in the course of subsequent experiments. Hemiholotransketolase 2 is the enzyme in which the only functional active center is the one exhibiting lower affinity for the coenzyme. In order to obtain this species of transketolase, active center 1, the affinity of which for thiamine diphosphate is higher, is to be blocked by an inactive analogue of the coenzyme, hydroxythiamine diphosphate	Saccharomyces cerevisiae

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	20	-	-	Saccharomyces cerevisiae

Storage Stability

EC Number	Storage Stability	Organism
2.2.1.1	4°C, 50% saturated solution of ammonium sulfate, pH 7.6	Saccharomyces cerevisiae

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	-	Saccharomyces cerevisiae	sedoheptulose 7-phosphate + D-glyceraldehyde 3-phosphate	-	?
2.2.1.1	D-xylulose 5-phosphate + D-ribose 5-phosphate	the active centers of the enzyme are nonequivalent with respect to ribose 5-phosphate binding. Under the conditions where only one out of the two active centers of transketolase is functional, their affinities for ribose 5-phosphate are identical. Nonequivalence becomes apparent when the substrate interacts with one of the two active centers. As a consequence, the affinity of the second active center for ribose 5-phosphate decreases	Saccharomyces cerevisiae	sedoheptulose 7-phosphate + D-glyceraldehyde 3-phosphate	-	?

Cofactor

EC Number	Cofactor	Comment	Organism	Structure
2.2.1.1	thiamine diphosphate	in the presence of Ca2+, the active centers of transketolase differ in their affinity for thiamine diphosphate by approximately one order of magnitude. Hemiholotransketolase 1 is the enzyme in which the only functional active center is the one exhibiting higher affinity for thiamine diphosphate. When adding an equimolar amount of thiamine diphosphate to apotransketolase, it becomes completely bound to the 1 active center and is not dissociated from it in the course of subsequent experiments. Hemiholotransketolase 2 is the enzyme in which the only functional active center is the one exhibiting lower affinity for the coenzyme. In order to obtain this species of transketolase, active center 1, the affinity of which for thiamine diphosphate is higher, is to be blocked by an inactive analogue of the coenzyme, hydroxythiamine diphosphate	Saccharomyces cerevisiae

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Release 2023.1 (January 2023)