Effect of the divalent metals on the ecto-PPase activity of <i>T. rangeli</i>.

<p>Panel A: Intact <i>T. rangeli</i> cells (10⁷ cells) were incubated in a reaction medium containing a cold buffer solution of 50 mM Tris-HCl, pH 7.2, 100 mM sucrose and 20 mM KCl, using 1 mM PPi as substrate in the absence (control) or presence of MgCl₂, MnCl₂ or CalCl₂ in a final concentration of 2 mM. Panel B: Intact <i>T. rangeli</i> cells (10⁷ cells) were incubated in the reaction medium described above, using 1 mM PPi as a substrate in the absence of a metal (control), in the presence of increasing concentrations of MgCl₂ or in the presence of 5 mM MgCl₂ and increasing concentrations of CaCl₂. The data represent the mean ± standard error, using at least three different cell suspensions. *Denotes a statistically significant difference (<i>p</i><0.05) compared with the control (no addition). **Denotes a significant difference (<i>p</i><0.05) compared with the ecto-PPase activity in the presence of 5 mM MgCl₂.