(A) Derivatization of AP sites in double-stranded oligonucleotide with 5 mM PMOA at 37 °C, with different buffers and catalysts. The percent unreacted oligonucleotide vs. time is reported. Points on the reaction rate curve at pH 8.0 containing sequential addition of enzymes employed during lysis of the nuclear pellet: a. RNase A & RNase T1 added. b. Proteinase K added, c. Puregene PP solution added, or reactions conducted at pH 7.0 or pH 7.4 without or with histidine. (B) Derivatization of AP sites in CT DNA with various concentrations of PMOA. Reaction condition: pH 7.4, 37 °C, 1.5 h. Each value represents the mean ± SD, n = 3.