Recent progress in enzyme immobilisation, enzyme production, coenzyme regeneration and enzyme engineering has opened up fascinating new fields for the potential application of enzymes in a large range of different areas. As more progress in research and application of enzymes has been made the more apparent has become the Iack of an up-to-date overview of enzyme molecular properties. The need for such a data bank was also expressed by the EC-task force "Biotechnology and Information". Therefore we started the development of an enzyme data information system as part of protein-design activities at GBF. The present book "Enzyme Handbook" represents the printed version of this data bank. ln future it is also planned to make a com­ puter searchable version available. The enzymes in the Handbook are arranged according to the 1984 Enzyme Commission Iist of enzymes and later supplements. Same 3000 "different" en­ zymes are covered. Frequently very different enzymes are included under the same E. C. number. Although we intended to give a representative overview on the molecular variability of each enzyme, the Handbook is not a com­ pendium. The readerwill have to go to the primary Iiterature for more detailed information. Naturally it is not possible to cover all numerous, up to 40 000, Iiterature references for each enzyme if data representation is to be concise as is intended.