Biochemical characterization of an acid phosphatase from Thermus thermophilus

A recombinant putative acid phosphatase from Thermus thermophilus was expressed and purified from Escherichia coli. The recombinant phosphatase displayed activities in a broad range of temperature, from 40 to 90 °C, with optimal temperature at 70 °C. In addition, the recombinant enzyme had activities in a wide range of pH, from 3.6 to 9.1, with optimal pH at 6 in acetate buffer and with optimal pH at 6.5 in Hepes buffer. Furthermore, it showed significant thermal stability and still possessed 44% residual activity after 70 °C treatment for 15 min. Moreover, the recombinant phosphatase showed broad substrates specificities for monophosphate esters, p-nitrophenyl phosphate (pNPP) being the most preferred substrate, and it was able to resist inhibition by sodium tartrate. Additionally, the recombinant protein formed stable oligomer under partially denatured conditions and required calcium ions for enzymic activity.