UV denaturation profiles of DNA duplexes with and without 2-OH-A. Effect of 2-OH-A:T pairing in the 6A repeat sequence (panel A) and in a random sequence (panel B); continuous line, 2-OH-A:T; dashed line, A:T. Thermal stability of DNA duplexes with A or 2-OH-A paired with T, G, C or A in the A-repeat sequence (panels E and C, respectively) and in the random sequence (panels F and D). Filled circle, A:T and 2-OH-A:T; empty circle, A:A and 2-OH-A:A; filled triangle, A:C and 2-OH-A:C; empty triangle, A:G and 2-OH-A:G.