Figure 1.

The 3CAPS AP–site analogue is chemically stable in physiological buffers. (A) Chemical structures of the natural AP-site (AP) and the analogues 3CAPS (12) and tetrahydrofuran (THF) (9), included in the synthetic repair substrates with a 5′–fluorescein label (F). (B) DNA substrates containing either G•U mismatches (MM), enzymatically produced AP-sites or 3CAPS were incubated in a physiological buffer supplemented with 130 μg/ml protein (BSA) at 37°C. The spontaneous degradation of DNA substrates was assessed over time, indicated by faster migrating product bands on denaturing gel electrophoresis. Lane C+ shows the degradation of substrates induced by heating to 99°C in alkaline conditions for 10 min. (C) Quantitative analysis of the chemical stability of the various substrates. Error bars, standard errors of the mean (SEM) of three experiments.