The rapid development and recent advances in this field seemed to justify a further meeting dealing primarily with protein interconversions and their biological significance rather soon after the first symposium of this kind, held under the direction of Professor G. BONSIGNORE of Genoa, in Santa Margherita Ligure, Italy, in May 1970. The proceedings of the Second International Symposium on Metabolic Interconversion of Enzymes, held in Rottach-Egern, in the Bavarian Alps, from October 27-30, 1971, under the auspices of the Gesellschaft Deutscher N aturforscher und Arzte bear witness to the high quality of the research reports and the lively discussions which ensued. There are contributions by a number of distinguished scientists and experts in the field who came from several European countries, Canada, Israel, Japan, the Soviet Union and the United States in order to participate in this symposium. We wish to express our sincere gratitude to the speakers for all their efforts. The main burden of the editorial work was carried by Dr. G. LOFFLER, Munich, ably as- Dr. A. R. FERGUSON, Freiburg, Dr. R. H. HASCHKE, Wiirzburg, Dr. A. HASILlK, sisted by Freiburg, Dr. L. HEILMEYER Jr., Wiirzburg, Dr. E. SIESS, Munich, and by the secretaries, Miss E. BAUER, Munich and Mrs. G. WEIDEMANN, Wiirzburg. To the publishers, Springer- Verlag Berlin Heidelberg New York, and especially to Dr. H. MAYER-KAUPP, we are greatly indebted for their cooperation.