Previous symposia on Metabolic Interconversion of Enzymes were held in 1970 (Santa Margherita-Ligure, Italy), 1971 (Rottach-Egern, Ger- many), 1973 (Seattle, USA) and 1975 (Arad, Israel). The present pub- lication reports the proceedings of the 5th International Symposium on Metabolic Interconversion of Enzymes, held in Titisee/Black Forest (Germany) from October 1st-5th, 1980. In the last few years, the number of enzymes for which control of activity by enzyme-catalyzed covalent modification, i.e., by intercon- version, is of recognized metabolic importance has increased so much that is was not possible to have every such enzyme considered during a 3-day conference. The organizers therefore decided to devote only one of the three sections to "metabolic interconversion" per se, and to cover in the other two sections "enzyme regulation by proteolytic modification" and "novel aspects of regulation". According to the IUP AC-IUB Commission on Biochemical Nomenclature (cf. J. Biol. Chem. 252,5939-5941 (1977)), modification by proteolysis is not in- cluded in "metabolic interconversion". Considering, however, the close interrelationship of these two types of enzyme control, it has become a tradition, beginning with the conference in Rottach-Egern 1971, to include proteolytic modification in our conferences.

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.