THE APPLICATION OF ENZYMES IN THE SYNTHESIS OF AMINO-ACIDS, PEPTIDES AND CARBOHYDRATES

Enzymatic transformations have recently assumed great importance in th e synthesis of enantiomerically pure amino acids and carbohydrates, pa rticularly as the requirement for efficient methods in catalytic asymm etric synthesis increases. A large number of enzymes, that catalyse a wide range of different synthetic transformations, have been identifie d and are currently being applied in many laboratories including our o wn. This Chapter will focus on recent work from the Edinburgh group an d will address the application of those enzymes that catalyse the (i) hydrolysis of esters (ii) the ring-opening of oxazolones in organic so lvents (iii) the hydrolysis and synthesis of glycosides (iv) the asymm etric synthesis of carbon-carbon bonds. Emphasis will be placed on the development of protocols for carrying out these biocatalytic transfor mations on a medium to large scale. The use of enzymes in the preparat ion of amino acid and carbohydrate derivatives will be illustrated by the syntheses of biologically active pharmaceutical intermediates and selected target molecules such as morphine-6-glucuronide, L-tert-leuci ne, pseudopeptides, and novel glycosidase inhibitors. Finally, a brief section on the use of enzymes in solid -phase synthesis will be inclu ded in which it will be shown that enzymes can be used not only to car ry out selective transformations on a solid support, but also to act a s highly selective reagents for the cleavage of the products by the de sign of appropriate enzyme-cleavable linker systems.