Transketolase organic synthesis

A number of mechanistically distinct enzymes can likewise be employed for the synthesis of product structures identical to those accessible from aldolase catalysis. Such alternative cofactor-dependent enzymes (e.g. transketolase) are emerging as useful catalysts in organic synthesis. As these operations often extend and/or... 

The sugar metabolism is a source of many enzymes, the transketolase (TK) being one of them. TK transfers an a-hydroxy carbonyl fragment from D-xylu-lose-5-phosphate onto D-ribose-5-phosphate, forming D-sedoheptulose-7-phos-phate and D-glyceraldehyde-3-phosphate (Scheme 5.14). Since this reaction is an equilibrium reaction and starting materials and products are of similar stability, it is not very versatile for organic synthesis. Fortunately TK also accepts pyruvate instead of xylulose. Under these modified circumstances carbon dioxide... 

The use of aldolases and transketolase has opened the way to many highly multifunctional organic compounds [1]. In organic synthesis, the most widely used dihydroxyacetonephosphate (DHAP) aldolase is the commercially available fruc-tose-1,6-bisphosphate aldolase from rabbit muscle (FruA). This enzyme is a key enzyme of the glycolytic pathway, reversibly catalyzing the cleavage of fructose-... 

In addition to the preparatively useful aldolases, several mechanistically distinct enzymes can be employed for synthesis of product structures identical w ith those accessible from aldolase catalysis. Such alternative enzymes (e.g. transketolase), w hich are actually categorized as transferases but also catalyze aldol-related additions w ith the aid of cofactors (Eigure 5.4) such as pyridoxal 5-phosphate (PEP), thiamine pyrophosphate (TPP), or tetra-hydrofolate (THE), are emerging as useful catalysts in organic synthesis. Because these operations often extend and/or complement the synthetic strategies open to aldolases, a selection of such enzymes and examples of their synthetic utility are included also in this overview . 

N.J. Turner, Applications of transketolases in organic synthesis, Curr. Opin. Biotechnol. 11 (2000) 527-531. 

I. Bolte, C. Demuynck, H. Samald, Utilization of enzymes in organic chemistry transketolase catalyzed synthesis of ketoses. Tetrahedron Lett. 28 (1987) 5525-5528. 

C. Demuynck, I. Bolte, L. Hecquet, H. Samaki, Enzymes as reagents in organic chemistry transketolase-catalyzed synthesis of D-[l,2- CJxylulose, Carhohydr. Res. 206 (1990) 79-85. 

---