Improvement of the catalytic properties of biological catalysts is equally important in the optimization of industrial processes as in the fundamental understanding of the catalytic machinery at the molecular level. The approaches taken are diverse and span from purely result-oriented, but nevertheless methodologically subtle, making and screening of combinatorial libraries to highly sophisticated tailoring of the environment of active sites. This volume illustrates four different concepts for modifying a given biocatalyst framework or create novel functions using Nature's basic building blocks. Summing up the state-of-the-art biocatalyst engineering it, serves as an orientational landmark and a platform for the specialist and non-expert alike to keep abreast of developments in this rapidly evolving field.