Purification and Properties of Adenosine 5'-Triphosphate Sulfurylase from the Thermophilic Bacterium Bacillus stearothermophilus

Abstract

ATP sulfurylase, which catalyzes the first step on the sulfate activation, was purified to apparent homogeneity from Bacillus stearothermophilus, with ammonium sulfate fractionation and successive column chromatography. The enzyme had an apparent molecular mass of 100 kDa, consisting of two equal-sized-44 kDa subunits. The optimum pH was about 8.5-8.7. Divalent cations such as Mn²⁺, Mg²⁺, and Co²⁺ were required for its activity. Apparent K_m values for ATP and SO₄^2- were 0.045 mM and 0.2 mM, respectively. The enzyme can use deoxyadenosine 5'-triphosphate as a substrate. The enzyme was thermostable and did not show significant loss of activity for 15 min of incubation up to 70°C, suggesting a practical use for a continuous reaction.