Figure 1.

Typical cross-correlation curves that were obtained from samples with and without restriction endonucleolytic activity at different analysis times. Assays were performed by using 10 nM labeled DNA substrate, incubated for 3 h at 37°C with 0.25 units/μl EcoRI (lower, thin lines) and without enzyme addition (upper, bold lines). Correlation times were 760 ms (dotted lines) and 120 s (solid lines) by using a 30 μm pinhole diameter and excitation power densities of 19 kW/cm² (488 nm) and 15 kW/cm² (633 nm).