Figure 3.

Poly[U]-induced channel blockade lifetimes were proportional to (a) mean polymer length and (b) inversely proportional to applied voltage. The plots show lifetimes for (a) peaks 1 (+), 2 (□), and 3 (•) in experiments using V = −120 mV with 13 different size selected poly[U]s and (b) for peaks 2 (□), and 3 (•) with poly[U] of mean length 215 nt at the indicated voltages. Although the peak 1 lifetime appeared to be independent of the applied voltage (data not shown), because this lifetime (≈100 μs) was barely a factor of 2 greater than the time resolution of our system, a slight voltage dependence could not be ruled out.