Today, as the large international genome sequence projects are gaining a great amount of public attention and huge sequence data bases are created it be­ comes more and more obvious that we are very limited in our ability to access functional data for the gene products - the proteins, in particular for enzymes. Those data are inherently very difficult to collect, interpret and standardize as they are highly distributed among journals from different fields and are often sub­ ject to experimental conditions. Nevertheless a systematic collection is essential for our interpretation of the genome information and more so for possible appli­ cations of this knowledge in the fields of medicine, agriculture, etc .. Recent pro­ gress on enzyme immobilization, enzyme production, enzyme inhibition, coen­ zyme regeneration and enzyme engineering has opened up fascinating new fields for the potential application of enzymes in a large range of different areas. It is the functional profile of an enzyme that enables a biologist or physician to analyse a metabolic pathway and its disturbance; it is the substrate specificity of an enzyme which tells an analytical biochemist how to design an assay; it is the stability, specificity and efficiency of an enzyme which determines its usefulness in the biotechnical transformation of a molecule. And the sum of all these data will have to be considered when the designer of artificial biocatalysts has to choose the optimum prototype to start with.