Inhibition of ATPase activity of the recA protein by ATP ribose-modified analogs

The single-stranded, DNA-dependent ATPase activity of purified recA protein was found to be inhibited competitively by ribose-modified analogs of ATP, 3'-O-anthraniloyl-ATP (Ant-ATP), and 3'-O-(N-methylanthraniloyl)-ATP (Mant-ATP). The Ki values for Ant-ATP and Mant-ATP were around 7 and 3 microM at pH 7.5, respectively. The inhibitions by these analogs were much stronger than that by ADP, which is also a competitive inhibitor for the ATPase activity of the recA protein. The Ki value for ADP is 76 microM. Ant-ATP and Mant-ATP reduced the Hill coefficient for ATP hydrolysis and thus contributed to the cooperative effect of ATP.