FIGURE 9.

Tryptophan fluorescence intensity of wild type ECD2 in the presence of 11-cis-retinal. Fluorescence spectra of wild type ECD2 polypeptide were collected at 25 °C in the presence of increasing amounts of 11-cis-retinal over the concentration range 0–10 μm as indicated. The concentration of ECD2 polypeptide was 0.1 mg/ml in 10 mm NaPO₄ (pH 7.5), 25 mm NaCl. The scans were conducted in triplicate, and the data were analyzed as described under “Experimental Procedures.”