Figure 8.

Effect of inhibitors on formation of hLigI—DNA complex. A radioactively labeled DNA substrate containing a single nonligatable nick (1 pmol) and hLigI (1 pmol) were incubated without or with the indicated compounds at 100 μM. After separation by native gel electrophoresis, labeled DNA and DNA—protein complexes were detected by phosphorImager analysis (A). Compound 25 is a simple competitive inhibitor with respect to nicked DNA. hLig1 (0.05 pmol) was incubated in the absence and presence of L25 at 12 μM (□) and 25 μM (▽) with increasing amounts of a linear nicked DNA substrate. Lineweaver—Burk double-reciprocal plots of initial reaction velocity versus substrate concentration are shown (B).