Figure 6. Xenopus SWS2, P434 absorption spectra

Absorption spectra of the Xenopus SWS2, P434 and its illumination changes in the presence of hydroxylamine in the dark. (A) The recombinant pigment generated with 11-cis retinal has an absorption maximum of 434 nm in the dark. Upon illumination, the spectrum blue shifts to 380 nm. (B) This pigment is sensitive to hydroxylamine in the dark. Illustrated are 14 representative spectra taken before and after the addition of hydroxylamine. Trace 1 is the spectrum of the pigment measured before addition of hydroxylamine and corrected for subsequent dilution when hydroxylamine is added. Traces 2-14 are spectra after the addition of hydroxylamine (50 mmol/L final concentration) at 1, 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, and 90 min. All spectra were measured in the dark at 20 °C. (C) Plotting the absorbance of all the spectra at 430 nm as a function of time illustrates the exponential loss of pigment in the presence of hydroxylamine.