Temperature and Metal Ions-Dependent Activity of the Family I Inorganic Pyrophosphatase from the Swine Roundworm Ascaris suum

Abstract

Temperature dependence, heat stability and metal ions-dependent activity were examined on the Family I inorganic pyrophosphatase (PPase) recently identified from Ascaris suum. Recombinant A. suum PPase (rAsPPase) showed an optimal activity at 55°C. The rAsPPase was heat stable at 40°C in the absence of added Mg²⁺ and at 50°C in its presence. The enzyme required divalent metal ions for its activity. The preferences for the metal ions (5 mM concentration) were in the order: Mg²⁺> Co²⁺> Cu²⁺> Fe²⁺> Zn²⁺> Mn²⁺. On the contrary, enzyme activity was inhibited by Ca²⁺. These findings suggest that catalytic features of AsPPase are consistent with the Family I PPases reported from a wide range of organisms.