Figure 3.

Measuring γ from anti-correlated photobleaching events. (A) Example trace (DNA10) showing a molecule from which γ can be calculated based upon the anti-correlated change in acceptor (red) and donor (green) intensity. Acceptor photobleaching is indicated with arrow. The bar above the panel shows the alternating laser colors during acquisition. The γ^Photobleach can only be calculated from molecules where acceptor photobleaching precedes donor photobleaching. (B) Histogram of individual γ^Photobleach values for each DNA molecule recorded under optical path 1 for DNA7 (orange), DNA10 (purple), DNA14 (green), and DNA19 (blue). (C) Cumulative histogram showing universal γ^Photobleach for DNA duplexes measured under optical path 1 (left), optical path 2 (middle), and optical path 3 (right).