Figure 5.

Spectral properties of blue cone opsin reconstituted with 11-cis-6mr-retinal compared with rod opsin reconstituted with 11-cis-6mr-retinal. a, UV-visible absorption spectra of blue cone opsin regenerated with 11-cis-6mr-retinal (B6mr) in dark conditions (black spectrum) and after illumination for 5 (orange spectrum) and 30 min (red spectrum). Sample illuminated for 30 min was then kept for 1200 min in the dark (red dotted spectrum). b, UV-visible absorption spectra of rod opsin regenerated with 11-cis-6mr-retinal (Rh6mr) in dark conditions (black spectrum) and after illumination for 1 min (red spectrum). Sample illuminated for 30 min was then kept for 1200 min in the dark (black dotted spectrum). c, HPLC elution profile of retinoid oximes extracted from dark-state B6mr (black line) or from B6mr illuminated for 5 min (red line). d, HPLC elution profile of retinoid oximes extracted from dark-state Rh6mr (black line) or from Rh6mr illuminated for 1 min (red line). e, photosensitivity of B6mr. Samples were illuminated with light from a 150-W Fiber-Lite source delivered through a 400–440-nm band pass interference filter at 20 °C. The percentage of residual pigment was plotted against the incident photon count and fitted with an exponential function. The slope of the fitting line corresponds to the relative photosensitivity of the pigment at the irradiating wavelength. Error bars represent standard deviation (S.D.). f, accessibility of the bulk solvent to the protonated Schiff base in blue cone opsin regenerated with 11-cis-retinal (Blue opsin; light blue) or 11-cis-6mr-retinal (B6mr; dark blue). The UV-visible absorption spectra were recorded every 2 min at 20 °C. The percentage of residual pigment was plotted as a function of time and fitted with an exponential function. Error bars represent S.D. φ, quantum yield.