Figure 4. UV melting profiles, (A) at 245 nm (–0.25 absorbance offset for the 22CT + 22AG mixture) and (B) at 295 nm (–0.02 offset for the mixture). Open circles, 22CT; filled triangles, 22AG; crosses, 22CT + 22AG. Strand concentration, 3 µM; 10 mM sodium cacodylate; 100 mM KCl; pH 6. (C and D) The effect of pH on the 295 nm absorbance of the mixture. Strand concentration, 3 µM; buffer composition: 10 mM sodium cacodylate or acetate; 100 mM NaCl (C) or KCl (D).