Properties of the ATP phosphohydrolase of the facultative thermophile Bacillus coagulans

Abstract The thermostability of the ATP phosphohydrolase of the facultative thermophile Bacillus coagulans has been investigated. Fractionation of disintegrated cell suspensions by differential centrifugation revealed a similar distribution of enzyme activity irrespective of growth temperature. Most of the activity was located in the membrane fraction. Thermostability of solubilized (BF₁) preparation from cells grown at 37°C or 55°C was similar, but membrane-bound BF₀BF₁ from 37°C-grown cells was inactivated at lower temperatures than that from 55°C-grown cells.
Inhibition of the membrane-bound (BF₀BF₁)ATPase by 4-chloro-7-nitro-benzofuran (NbfCl) and quercetin, which both act on the BF₁ portion of the enzyme, was different from that seen with the soluble (BF₁) enzyme. The results show that some modification of BF₁ must occur when the enzyme is membrane-bound.