FIG. 7.

pAp phosphatase activity of S. mutans SMU.1297 protein. (A) pAp phosphatase activity as a function of time. Reaction mixtures containing 5 μg of protein and 40 μM pAp were incubated for various lengths of time at room temperature. The reaction buffer contained either MnCl₂ or MgCl₂, as described in the text. Reactions were stopped by the addition of an equal volume of 100 mM EDTA, the liberated phosphates were quantified using a phosphate colorimetric assay kit (malachite green method) as described in Materials and Methods, and the absorbance was measured using a BioTek Synergy HT reader, at 600 nm. (B) pAp phosphatase activity as a function of protein concentration. The assay for phosphatase activity was carried out for 20 min, at room temperature, in the presence of increasing amounts of His-SMU.1297 protein and 40 μM pAp. The liberated phosphate was quantified as described for panel A. For both the graphs, the y axis shows percent conversion of pAp to AMP and inorganic phosphate.