A sulfite-dependent adenosine triphosphatase of Thiobacillus thiooxidans. Its partial purification and some properties

A sulfite-dependent ATPase EC 3.6.1.3 EC] ] of Thiobacillus thiooxidanswas activated and solubilized by treatment with trypsin EC3.4.4.4 EC] ], and purified 84-fold with a 32% recovery. It requiredboth Mg²⁺ and SO₃^2– for full activity, and its optimumpH was found at 7.5–8.0. Mn²⁺, Co²⁺, and Ca²⁺ could partiallysubstitute for Mg²⁺, while SeO₃^2– and CrO₄^2– couldpartially substitute for SO₃^2–. The enzyme hydrolyzed ATP and deoxy-ATP most rapidly and otherphosphate esters were poorer substrates. The apparent Km valuefor ATP was 0.33 mM. The enzyme activity was strongly inhibitedby 0.2 mM NaN₃ and 10 mM NaF. (Received July 27, 1977; )