Unique properties of cell wall-associated β-glucosidases

Abstract Two maize ( Zea mays L.) root cell wall-associated β-glucosidases were compared to two cellular forms. The ionically bound cell wall enzyme was more difficult to dissociate from the cell wall compared to artifactually bound cytosolic β-glucosidase activity. The ionically bound cell wall enzyme also had an isoelectric pH of 6.8–7.0 compared to the acid p I of the cytosolic enzyme (4.8–5.2). A second cell wall enzyme was very tightly bound to the cell wall and could not be extracted with 3 M NaCl or LiCl. Both the ionically bound cell wall β-glucosidase and the tightly bound β-glucosidase were more thermostable at 40°C and 50°C compared to the cytosolic enzyme and the particulate intracellular isozyme. The tightly bound cell wall β-glucosidase was the only thermostable enzyme at 60°C.