Alkaline phosphatase activity in a strain of Bacterionema matruchotii

Protein from the soluble fraction of Bacterium matruchotii cells propagated in a medium containing no added inorganic phosphate was fractionated by gel permeation chromatography. The bulk of phosphatase activity assayed at pH 8.0 was found in fractions equivalent to a molecular weight of 6 x 10(5) daltons. Substrate saturation kinetics indicate at Km of 0.75 mM for p-nitrophenylphosphate. Activity was stimulated more than two-fold by Zn++ at 1 mM, but was significantly reduced by EDTA, Ca++ and inorganic phosphate. The enzyme(s) shows negligible activity at pH below 6.0 and has a narrow optimum between 7.5 and 8.5.