Chapter II - Control of Synthesis and Breakdown of Glycogen, Starch and Cellulose

Abstract

Publisher Summary This chapter discusses the developments related to the control of synthesis and breakdown of glycogen, starch, and cellulose. The main emphasis is laid on the regulation of biosynthetic and degradative pathways. The synthesis of glycogen, in vitro , by the action of a purified enzyme was achieved by C.F. Cori, G. Schmidt and G. T. Cori in 1939. From this time until rather recently the prevalent view among biochemists was that in living systems the same reversible enzymatic reactions are responsible for synthesis and degradation of energy stores. Thus, it was generally accepted that phosphorylase in vivo acted both ways and catalyzed the formation and the breakdown of glycogen. This view was further supported by the fact that the phosphorylase reaction is without a doubt reversible and can form glycogen in vitro . However, thermodynamically, the synthetase reaction favors the formation of α-1,4-glycosidic bonds, which is much more than the phosphorylase reaction and the thermodynamic advantages beat the comparatively low actual activity of the synthetase.