Inorganic pyrophosphatase from Ferrobacillus ferrooxidans (Thiobacillus ferrooxidans)

Abstract

An inorganic pyrophosphatase was isolated from Ferrobacillus ferrooxidans and purified 21-fold. The cation Mg2+ was required for maximum activity; Mn2+, Zn2+, and Co2+ supported less than 10% of the activity with Mg2+. The pH optimum of the enzyme was between 7.5 and 8.5, using a magnesium to pyrophosphate ratio of one. The purified enzyme was unable to hydrolyze adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, or various other monophosphates; p-nitrophenyl-phosphate, the substrate for alkaline pyrophosphatase, was not hydrolyzed. Sulfhydryl binding agents did not inhibit enzyme activity, and the enzyme, in the presence of Mg2+, was heat-stable.