Whereas several areas of biocatalysis - in particular the use of easy-to-use hydrolases, such as proteases, esterases and lipases - are sufficiently well researched to be applied in every standard laboratory, other types of enzymes are still waiting to be discovered with respect to their applicability in organic-chemistry transformations on a preparative scale. This latter point is stressed in this volume, which concentrates on the 'newcomer-enzymes'which show great synthetic potential.