Fig. S3.

Inhibition of Vent pol by PP_i and Mg²⁺. (A) Amount of pyrophosphorolysis resulting from a correctly matched p/t as a function of [PP_i]. As the pyrophosphate concentration increases, the amount of pyrophosphorolysis increases until it peaks at 15 mM. A concentration higher than 15 mM results in inhibition. Each reaction was carried out for 1 h. (B) Amount of incorporation as a function of [Mg²⁺]. At concentrations higher than 25 mM, the Mg²⁺ begins to inhibit the forward reaction. The black solid line corresponds to a 1-min reaction, the red dashed line to a 5-min reaction, and the green dashed line to a 15-min reaction.