Quenching of Trp-151 Fluorescence. Changes in polarity of the
environment surrounding Trp-151 were studied further by fluorescence
quenching. The water-soluble ions Cs (Fig. 6A) and
I (Fig. 6B) were used as collisional quenchers to probe the
solvent accessibility of Trp-151 in the absence or presence of
TDG. Acrylamide, another collisional quencher, which is neu-