Characterization of the inorganic pyrophosphatase from the pathogenic bacterium Helicobacter pylori

A cytoplasmic pyrophosphatase [E.C. 3.6.1.1.] was partially purified from H elicobacter pylori. The molecular mass was estimated to be 103 kDa by gel f iltration. Results of SDS-PAGE suggested that the enzyme consists of six id entical subunits of 19.1 kDa each. The enzyme specifically catalyzed the hy drolysis of pyrophosphate and was very sensitive to NaF, but not to sodium molybdate. The optimal pH for activity was 8.5, Mg2+ was required for maxim al activity; Mn2+, Co2+, and Zn2+ poorly supported hydrolytic activity. The pyrophosphatase had an apparent K-m, for Mg-PPi2- hydrolysis of 90 mu M, a nd a V-max estimated at 24.0 mu mol P-i min(-1) mg(-1).