Distribution of several proteases inside and outside the central vacuole of Chara australis.

Abstract
Vacuolar sap was separated by intracellular perfusion and the distribution of proteases was studied in the giant alga C. australis. Caseinolytic and hemoglobin-digesting activities were found to be higher at low pH, and about 85% of total activity was localized in the central vacuole. The optimal pH for carboxypeptidase activity measured using N-carbobenzoxy-L-phenylalanyl-L-alanine as a substrate was around 5, and about 95% of total activity was localized in the vacuole. Moreover a substantial portion (40%) of aminopeptidase activity, measured at pH 5.5 using L-leucine-.beta.-naphthylamide as a substrate, was found in the vacuole.