Figure 3.

hPifHD interactions with ssDNA. (A) Binding to ³²P-end-labeled poly T probes of increasing length (0.1 nM probe; 0.1, 0.5 and 2.5 nM hPifHD) was assesed by gel-shift assay. Significant binding was detected only with probes of 35 bases or greater (lanes 9–28). (B) Stimulation of hPifHD ATPase activity as a function of probe length and concentration. hPifHD (50 nM) was incubated with oligonucleotides T8, T16, T30 and T55 at three concentrations, 25, 50 and 200 nM, and product release (from 5 µl of reaction) determined after 10 min. During this time period ATPase activity was in the linear range.