FIG. 5.

Optimal reaction conditions for the exonuclease activity of Apn2 protein. The exonuclease activity of GST-Apn2 was assayed under various conditions, using the S-4 partial DNA duplex substrate. (A) Time dependence; (B) pH dependence (morpholineethanesulfonic acid [MES] was used for pHs 5 and 6, and Tris was used for pHs 6.8, 7.5, 8.0, and 8.8); (C) NaCl concentration dependence; (D) metal ion dependence. The first lane contains reaction mixture without any metal ions in the reaction buffer.