Figure 5. Absorbance spectra of apo and holo-rEBP-C61S.

Following protein-ligand reconstitution and removal of unbound carotenoid the absorbance spectrum of holo-rEBP-C61S (1 mg.mL^-1) was measured between 260 nm and 700 nm, against a reference solution of 20 mM HEPES pH 8.0 (yellow line). Spectra of 1 mg.mL^-1 apo-rEBP-C61S in 20 mM HEPES pH 8.0 (blue line) and purified 9′-cis-echinenone at 0.9 mg.mL^-1 in methanol (red line) are shown for comparison.