Photophysics of phenylalanine analogues - Part 2. Linear analogues of phenylalanine

The photophysical properties (fluorescence quantum yields and lifetimes) of linear analogues of phenylalanine (Phe) [beta -homophenylalanine (beta -Hp h), beta -phenylalanine (beta -Phe), phenyglycine (Phg)] in water at pH = 6 and 1 have been measured. The obtained results indicate that relative spac e location of the amino, carboxyl groups and phenyl chromophore influence o n photophysical properties at both pH. In acidic solution (pH = 1) lower fl uorescence quantum yields and fluorescence lifetimes than observed at pH = 6 for all studied compounds suggest that the protonated carboxylic group ef ficiently quenches phenyl fluorescence. It was found that the proximity of the protonated amino group and the phenyl ring modify the photophysical pro perties of phenylalanine analogues beta -Phe and Phg. (C) 2001 Elsevier Sci ence B.V. All rights reserved.