Function
Transketolase (TKT) catalyzes two opposite reactions. The synthesis of sedoheptulose-7-P in the pentose phosphate pathway using thiamine diphosphate (TPP) as co-factor; and the conversion of sedoheptulose-7-P and glyceraldehyde-3-P to aldose and ketose in the Calvin cycle[1]. Split-gene TKT is found in the hyperthermophilic bacterium Carboxydothermus hydrogenoformans and is reconstituted from 2 separate polypeptide chains[2].
Structural highlights
The active site of TKT contains a ligand-cofactor adduct.[3] Water molecules are shown as red spheres. Ca coordination site.
3D Structures of transketolase
Transketolase 3D structures
- ↑ Verschueren KH, Kingma J, Rozeboom HJ, Kalk KH, Janssen DB, Dijkstra BW. Crystallographic and fluorescence studies of the interaction of haloalkane dehalogenase with halide ions. Studies with halide compounds reveal a halide binding site in the active site. Biochemistry. 1993 Sep 7;32(35):9031-7. PMID:8369276
- ↑ James P, Isupov MN, De Rose SA, Sayer C, Cole IS, Littlechild JA. A 'Split-Gene' Transketolase From the Hyper-Thermophilic Bacterium Carboxydothermus hydrogenoformans: Structure and Biochemical Characterization. Front Microbiol. 2020 Oct 30;11:592353. doi: 10.3389/fmicb.2020.592353., eCollection 2020. PMID:33193259 doi:https://dx.doi.org/10.3389/fmicb.2020.592353
- ↑ Asztalos P, Parthier C, Golbik R, Kleinschmidt M, Hubner G, Weiss MS, Friedemann R, Wille G, Tittmann K. Strain and near attack conformers in enzymic thiamin catalysis: X-ray crystallographic snapshots of bacterial transketolase in covalent complex with donor ketoses xylulose 5-phosphate and fructose 6-phosphate, and in noncovalent complex with acceptor aldose ribose 5-phosphate. Biochemistry. 2007 Oct 30;46(43):12037-52. Epub 2007 Oct 3. PMID:17914867 doi:10.1021/bi700844m
