Independent induction of sister-chromatid exchanges by 3-aminobenzamide and ultraviolet radiation in HeLa cells.

The effect of 3-aminobenzamide in HeLa cells was examined in several aspects. 10(-3) M 3-aminobenzamide inhibited poly(ADP-ribose) polymerase activity to more than 95% in disrupted nuclei of HeLa cells. The mode of inhibition of the enzyme was competitive inhibition with NAD at a Ki value of 2.5 microM 3-aminobenzamide. The combined treatment of HeLa cells with 3-aminobenzamide and ultraviolet radiation revealed the independent induction of SCEs by these 2 agents.