Analytical reversed-phase chromatograms of fluorescently-labeled A1-A1 monitored at 500 nm. Chromatogram of A1-A1 eluted with a linear gradient of 1% per minute. A1-A1 is eluted from the column at about 28% of acetonitrile/TFA. (Inset) Chromatogram of A1-A1 eluted with a 0.1% per minute gradient of acetonitrile/TFA starting at 9 minutes from about 26% of acetonitrile/TFA. Elution trace of mouse serum (red), A1-A1 without serum (black), and A1-A1 incubated with serum for 2 hours at 37°C (green).