Figure 5.

Droplet-based HIV-1 protease activity assay. (A) Histogram analysis of the droplet assay distribution included ∼240 000 droplets, which were irradiated with UV light (0.95 J/cm²) and incubated (∼25 min) prior to detection. Empty droplet fluorescence intensities (brown) differ significantly from fluorescence of droplets occupied with 1 (red), 2 (blue), or 3+ (yellow) PC-pepstatin A inhibitor beads. Histogram data derived from occupied droplets were magnified (30-fold) for display. (B) The initial encounter probabilities deviate from the Poisson distribution. Deviations decrease over the course of the experiment as the bead introduction rate slows.