THIAMIN-DEPENDENT ENZYMES AS CATALYSTS IN CHEMOENZYMATIC SYNTHESES

Enzymes are increasingly being used to perform regio- and enantioselec tive reactions in chemoenzymatic syntheses. To utilize enzymes for unp hysiological reactions and to yield novel products, a broad substrate spectrum is desirable. Thiamin diphosphate (ThDP)-dependent enzymes va ry in their substrate tolerance from rather strict substrate specifici ty (phosphoketolases, glyoxylate carboligase) to more permissive enzym es (transketolase, dihydroxyacetone synthase, pyruvate decarboxylase) and therefore differ in their potential to be used as biocatalysts. We give an overview of the known substrate spectra of ThDP-dependent enz ymes and present examples of multi-enzyme or chemoenzymatic approaches which involve ThDP-dependent enzymes as biocatalysts to obtain pharma ceutical compounds as ephedrine and glycosidase inhibitors, sex pherom ones as exo-brevicomin, C-13-labeled metabolites, and other intermedia tes as 1-deoxyxylulose 5-phosphate, a precursor of vitamins and isopre noids. (C) 1998 Elsevier Science B.V. All rights reserved.