Trp fluorescence? Protein aggregation? Did you check 90 degrees scattering signal?

dear Juha-Matti

 I incubated proteins sample in different concentration of GnHCl (0-6M)

for 3 hours .and then recorded the fluorescence spectra in both 280nm and 295 nm excitation wavelength. unexpectedly the intensity of   fluorescence spectra  were enhanced by higher concentration of GnHCl in 280nm.but in 295 nm the same result obtained in 3M. other concentration were close to each other.

How about the shape of the spectra? Could you show us the emisson spectra acquired at 280 and 295 nm excitation with 3 and 6 M GnHCl? Aggregation ìs still one possibility as it may affect both tryptophan fluorescence and scattering.