The intrinsic fluorescence characteristics of sarcoplasmic reticulum membranes

The fluorescence characteristics of tryptophan in sarcoplasmic reticulum, were investigated to gain information concerning its location and environment within the intact membrane system. With an excitation of 295 nm, tryptophan has an emission maximum of 330 nm characteristic of tryptophan in a buried hydrophobic environment. At the wavelength studied only a faint contribution of tyrosine is present. The changes observed in the presence of urea 8 M suggest only a partial exposition of the aromatic residues.