Figure 11. Emission spectra of X4IRBP and the Arg¹⁰⁰⁵->Gln mutant showing the quenching of intrinsic protein fluorescence upon binding all-trans retinol

Solutions of 1 µM mutant and X4IRBP were excited at 280 nm. Emission was measured from 300 nm to 540 nm in the absence of all-trans retinol (A) and then five min after adding 7.1 µM all-trans retinol (B). Note the quenching of protein fluorescence at 340 nm upon addition of all-trans retinol.