The high pressure effects on fluorescence of free tryptophan (Trp) and its
derivatives, N-acetyl-tryptophan (AT), N-acetyl-tryptophanamide (NATA), try
ptophanamide (TA), and tryptophan, containing 6-polypeptides in aqueous sol
ution, were investigated in a pressure range from 0.1 to 650 MPa, It was fo
und by analyzing the center of spectral mass in the wave length range from
300 to 450 nm that high pressure shifted the fluorescence spectra of all th
ese species to red direction: 421 cm(-1) for Trp, 305 cm(-1) for AT, 310 cm
(-1) for NATA, 265 cm(-1) for TA, and 220 cm(-1) for single tryptophan cont
aining 6-polypeptides. All the fluorescence efficiencies (i.e., quantum yie
ld) of the compounds were reduced with pressure except free tryptophan wher
e its fluorescence efficiency was enhanced with pressure. Glycerol, ethanol
, and pH obviously influenced the pressure effects on their fluorescence ch
aracteristics. Since the tryptophan fluorescence is usually used as a probe
for protein structural investigation, these findings suggested that the in
trinsic pressure effect on tryptophan (or its derivatives) must be taken in
consideration to explain the phenomenon observed in high pressure study on
biomolecules when using the usual fluorospectroscopic approaches. In the p
resent investigation, the mechanisms involved for pressure effects on trypt
ophan and its derivatives were explored and discussed. (C) 2000 Academic Pr
ess.