PURIFICATION AND PROPERTIES OF ADENOSINE 5'-TRIPHOSPHATE SULFURYLASE FROM THE THERMOPHILIC BACTERIUM BACILLUS-STEAROTHERMOPHILUS

ATP sulfurylase, which catalyzes the first step on the sulfate activat ion, was purified to apparent homogeneity from Bacillus stearothermoph ilus, with ammonium sulfate fractionation and successive column chroma tography. The enzyme had an apparent molecular mass of 100 kDa, consis ting 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 i ts activity, Apparent K-m values for ATP and SO42- 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 signific ant loss of activity for 15 min of incubation up to 70 degrees C, sugg esting a practical use for a continuous reaction.