SOME PROPERTIES OF INORGANIC PYROPHOSPHATASE FROM BACILLUS-SUBTILIS

Inorganic pyrophosphatase (pyrophosphate phosphohydrolase, EC 3.6.1.1; PPase) from Bacillus subtilis was purified to a homogeneous state ele ctrophoretically when analysed by SDS-PAGE. The enzyme consists of six identical subunits; the molecular weight of the native enzyme estimat ed by gel filtration was approx. 120 000, and denaturing polyacrylamid e gel electrophoresis gave a single band corresponding to 24 000. The enzyme absolutely required a divalent cation for its activity. Mg2+ wa s most effective, showing two steps of concentration-dependent activat ion. Mg2+ could be partially replaced by Mn2+ and Co2+. The enzyme was thermostable in the presence of Mg2+, and no loss of activity was obs erved on the incubation at 55 degrees C for an hour. (C) 1997 Elsevier Science Ltd.