Figure 5.

Fluorescence changes associated with AFB₁ exo-8,9-epoxide interaction with DNA. A solution of the epoxide [7 μM in (CH₃)₂CO] was mixed with 10 volumes of either (a) 10 mM sodium EDTA buffer (pH 6.2) or (b) the same buffer containing DNA under the same conditions (temperature, reagent sample, buffer, instrument parameters, and others). The solid lines show exponential fits. (A) Hydrolysis control reaction k_obs = 0.59 ± 0.01 s⁻¹; + 0.10 mg⋅ml⁻¹ dsDNA (= 0.32 mM monomer equivalents), k_obs = 0.82 ± 0.02 s⁻¹ (39% difference). (B) Hydrolysis control reaction k_obs = 0.77 ± 0.01 s⁻¹; + poly d(AT) 0.20 mg⋅ml⁻¹, k_obs = 1.03 ± 0.03 s⁻¹ (33% difference). (C) Hydrolysis control reaction k_obs = 0.62 ± 0.01 s⁻¹, + 0.15 mg⋅ml⁻¹ ssDNA, k_obs = 0.89 ± 0.02 s⁻¹ (40% difference).