Enzymes of glycogen mobilization in the photosynthetic procaryote,Anacystis nidulans

Glycogen, the principal storage compound of assimilatory products in Anacystis nidulans, is synthesized in the light and degraded in the dark. ¹⁴C-labelled glycogen and its radioactive limit dextrin obtained by phosphorylase action were used as substrates to identify enzymes involved in glycogen mobilization. A crude homogenate of cells kept in the dark contained the following enzymes: glycogen phosphorylase (EC 2.4.1.1.) that is firmly bound to glycogen, a debranching enzyme that hydrolyzes 1,6--glucosidic bonds, and an -glucosidase (EC 3.2.1.20). Other amylolytic enzymes were not detectable Using ion exchange chromatography on DEAE-cellulose, -glucosidase and the debranching enzyme could be partly separated from each other and completely from the phosphorylase-glycogen complex. On the basis of their known substrate specificities, the cooperation of these 3 enzymes is sufficient to account for the complete conversion of glycogen into glucose and glucose 1-phosphate.