Characterization and synthesis regulation of Penicillium italicum 1,6-beta-glucanase

The filamentous fungus Penicillium italicum when grown in a synthetic medium, produced and secreted 1,6-beta-glucanase into the culture medium. This enzyme has been partially purified by gel filtration. After this step the active fractions were free of 1,3-beta-glucanase, alpha-amylase and beta-glucosidase activities. Only four proteins, one associated with the enzyme, were found by polyacrylamide gel electrophoresis under non denaturing conditions. The enzyme behaves as an acidic protein (pI 4.65) with an optimum pH of 5 and an endohydrolytic mode of action. The activity was also found associated with the mycelium. Its synthesis was repressed by glucose or growth-promoting sugars. Derepression in low glucose containing medium required protein synthesis. 8-Hydroxyquinoline, an RNA synthesis inhibitor, added during the derepression period did permit some increase in the specific activity but prevented it when added at the beginning of that period.