The F1 portion of H(+)-translocating ATPase as purified from membrane vesicles of Vibrio parahaemolyticus by a rapid procedure. The whole purification process (from culture of cells to purification of the enzyme) could be completed in 1 day. The F1-ATPase consists of five subunits (alpha, beta, gamma, delta and epsilon) like F1 of Escherichia coli and other microorganisms. The F1-ATPase of V. parahaemolyticus showed some interesting properties. Its activity was greatly stimulated by high concentrations (about 0.5 M) of SO4(2-), SO3(2-) and CH3COO-, their effects decreasing in this order. Among the anions tested, Cl- and NO3- were ineffective, or rather inhibitory, and cations had no significant effects. Ethanol (or methanol) stimulated the activity 2- to 3-fold. The activity was inhibited by 4-acetamido-4'-isothiocyanostilbene 2,2'-disulfonate (SITS) (an anion exchanger inhibitor), tetrachlorosalicylanilide (TCS) (an H+ conductor), azide and N-ethylmaleimide. Zinc inhibited the activity only slightly, although it strongly inhibited the ATPase activity in membrane vesicles.