2.2.1.1 additional information as opposed to the kinetically stabilized carbanion/enamine intermediate in transketolase when reconstituted with the native cofactor, 2-(1,2-dihydroxyethyl)-4'-monomethylaminothiamin diphosphate is rapidly released from the active centers during turnover and accumulates in the medium on a preparative scale 690708 2.2.1.1 NAD+ - 756083 2.2.1.1 thiamine diphosphate - 485992, 485993, 485994, 485995, 485996, 485997, 485998, 485999, 486001, 486004, 486009, 486023, 658646, 672285, 685766, 691270, 691298, 691423, 691433, 691763, 692645, 692925, 693289, 693291, 694066, 735401, 735415, 735416, 735708, 735721, 735856, 735938, 736657, 736993, 756232, 756629, 756713, 756894, 756895, 757041, 757197, 757326, 757895, 758271, 758383, 758509 2.2.1.1 thiamine diphosphate 0.9 mol thiamine diphosphate per mol subunit 486011 2.2.1.1 thiamine diphosphate 1 catalytic site per enzyme molecule 486000 2.2.1.1 thiamine diphosphate 2 catalytic sites per enzyme molecule 486000 2.2.1.1 thiamine diphosphate 2 mol thiamine diphosphate per mol enzyme 486002, 486003, 486007 2.2.1.1 thiamine diphosphate additional thiamine does not enhance activity 486006, 486008, 486011, 486012, 486013 2.2.1.1 thiamine diphosphate an active site cleft is formed between the two monomeric units allowing the cofactors thiamine diphosphate and Mg2+ to bind, such that the N-terminal domain I of chain A binds the diphosphate moiety of thiamine diphosphate, and domain II of chain B interacts with the aminopyrimidine ring. The diphosphate moiety of thiamine diphosphate is anchored in place through a number of hydrogen bonds formed with residues Thr48, His85, Ser176, Asp177, Gly178, Asn207, Ile209 and His283 from one monomer, crystallization data 720609 2.2.1.1 thiamine diphosphate application of a theoretical model of interactions between ligand-binding sites in a dimeric protein for the analysis of thiamine diphosphate binding to yeast transketolase 672632 2.2.1.1 thiamine diphosphate bound at the subunit interface 690883 2.2.1.1 thiamine diphosphate dependent on 756083, 756453, 756467 2.2.1.1 thiamine diphosphate donor substrates (e.g. hydroxypyruvate or dihydroxyacetone) increase the affiniffty of the coenzyme for transketolase, whereas acceptor substrates do not. The effect of the substrate on the interaction of the coenzyme with apotransketolase and on stability of the reconstituted holoenzyme is caused by generation of 2-(alpha,beta-dihydroxyethyl)thiamine diphosphate (an intermediate product of the transketolase reaction), which has higher affinity for apotransketolase than thiamine diphosphate 672281 2.2.1.1 thiamine diphosphate homology modeling. The aminopyrimidine ring of thiamine diphosphate establishes weak hydrogen bonds, main interactions are focused on the diphosphate moiety, which maintains seven stable hydrogen bonds. H77, which forms a hydrogen bond with the diphosphate, is a conserved residue. Presence of a substrate channel 699615 2.2.1.1 thiamine diphosphate i.e. functional form of vitamin B1 486000 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 690697 2.2.1.1 thiamine diphosphate interaction with the coenzyme binding site of the enzyme is described 674081 2.2.1.1 thiamine diphosphate Km value is 0.074 mM 718950 2.2.1.1 thiamine diphosphate Km-value 0.0018 mM 657667 2.2.1.1 thiamine diphosphate negative cooperativity between apoenzyme and thiamine diphosphate in presence of Ca2+ or Mg2+ 659740 2.2.1.1 thiamine diphosphate not thiamine, thiamine mono-or triphosphate 485991, 486005, 486006 2.2.1.1 thiamine diphosphate produces a degree of structure similar to that of the fully reconstituted holo-transketolase dimer without urea. Thiamine diphosphate binds to apo-transketolase in the absence of the metal ion, though in a catalytically inactive form 692117 2.2.1.1 thiamine diphosphate requirement, thiamine diphosphate protein, tightly bound 486012, 486013 2.2.1.1 thiamine diphosphate theoretical analysis of interaction between thiamine diphosphate-binding sites of transketolase and determination of equilibrium and kinetic constants of individual stages of the interaction between thiamine diphosphate and the apoenzyme in the presence of Ca2+ 672288 2.2.1.1 thiamine diphosphate thiamine B-ring is an essential component of catalysis 691299 2.2.1.1 thiamine diphosphate thiamine diphosphate increases the stability of the apoenzyme regardless of wether Mg2+ or Ca2+ is present in the medium 675747 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 719890 2.2.1.1 thiamine diphosphate two-step mechanism of interaction of thiamine diphosphate with transketolase. Formation of inactive intermediate complex followed by its transformation into catalytically active holoenzyme 691025 2.2.1.1 thiamine diphosphate with different affinities for the cofactor 486002