Figure 3.

AP endonuclease activity on ssDNAs containing various Spacers. Different ssDNAs (100 nM) containing (a) alkane spacers, (b) polyethylene glycol spacers, (c) dSpacer and spacer C3, and (d) sulfur atom spacers were incubated with 5 nM (a–c) or 10 nM (d) of TeuendoIV at 55 °C for the indicated time. For the Spacer disulfide bond (S-S), the NAD⁺ (1.0 mM) was substituted for DTT in the reaction buffer. Uppercase letter M denotes oligonucleotides marker. The cleavage percentages of substrates are listed at the bottom of each panel. The symbol of black asterisk and the red letter X denote the fluorescein (6-FAM) group at the 5′-end and the AP-sites, respectively.