Characterization of ATPase Activity in Brush Border Membrane Vesicles from the Silkworm, Bombyx mori

Brush border membrane vesicles (BBMV) from the midgut epithelial cells of silkworm larvae were prepared. ATP hydrolyzing activity (ATPase activity) was associated with the BBMV. ATPase activity without Mg2 + was not observed at pH 7 but substantial ATP hydrolyzing activity was observed at pH 7 with Mg2 +. The enzyme required Mn2 +, Mg2 +, or Ca2+ ions. The enzyme also hydrolyzed ITP and GTP but not p-NPP, ADP, or AMP. KNO3 and NEM strongly inhibited the ATPase activity. Behaviours of the ATPase against inhibitors suggested that it resembled vacuolar type ATPase.