Figure 3

The effect of ionic strength on TaqII REase at pH 8.0 in the presence of the SIN/DMSO combination range, maximally stimulating the specificity change. 0.3 μg (1.2-pmol GACCGA recognition sites) PCR(SINGLE) substrate was digested with 6 pmol TaqII in 50 μl of the reaction buffer: 40 mM Tris–HCl, pH 8.0, at 65°C, 10 mM MgCl₂, 1 mM DTT, BSA 100 μg/ml, 100 μM SIN, 30% DMSO for 16 h at 65°C. Lane K, undigested PCR fragment; lane M, Sigma PCR 20-bp Low Ladder (selected bands marked); lanes 1–7: digested PCR fragment; lane 1, without SIN and (NH₄)₂SO₄; lane 2, with SIN and without (NH₄)₂SO₄; lanes 3–7 contain SIN and increasing concentrations of (NH₄)₂SO₄: xlane 3, 5 mM (NH₄)₂SO₄; lane 4, 10 mM; lane 5, 20mM; lane 6, 30 mM; lane 7, 40mM.