A plasma-membrane associated ATPase from the acidophilic bacterium Acidiphilium cryptum

A membrane-bound ATPase of Acidiphilium cryptum, an acidophilic bacterium of mine origin, has been studied. The enzyme has a pH optimum of 8.4 Mg2+ is required for its activity and could be replaced by Mn2+, but not by Ca2+. The enzyme shows a strong preference for ATP as substrate, with the apparent Km of about 0.2 mM. Sulphite ion significantly stimulated the enzyme activity. N,N'-Dicyclohexylcarbodiimide, oligomycin, and azide strongly inhibited the enzyme, whereas vanadate was without effect, suggesting that the A. cryptum ATPase might be of F0F1 type.