IN-VITRO SITE-SPECIFIC INCORPORATION OF FLUORESCENT-PROBES INTO BETA-GALACTOSIDASE

Fluorescence spectroscopy is a powerful biophysical technique for stud ying protein structure, function, dynamics, and intermolecular interac tions. Such studies are often conducted using intrinsic probes, such a s tryptophan residues, or extrinsic probes introduced by post-translat ional modification, such as dansyl. Specificity, however, is often a c oncern since many proteins contain more than one tryptophan and chemic al modification often will occur at more than one site. Herein we repo rt the in vitro, site-specific incorporation of three fluorescent amin o acid analogues, 5-hydroxytryptophan, 7-azatryptophan, and epsilon-da nsyllysine, each of which was incorporated into beta-galactosidase at a single designated site.