DIRECT INCORPORATION OF UNPROTECTED KETONE GROUPS INTO PEPTIDES DURING SOLID-PHASE SYNTHESIS - APPLICATION TO THE ONE-STEP MODIFICATION OF PEPTIDES WITH 2 DIFFERENT BIOPHYSICAL PROBES FOR FRET

An amino acid bearing an unprotected ketone group, (2S)-aminolevulinic acid, was incorporated into a synthetic peptide using standard Fmoc-b ased solid-phase methods. The ketone group remained unharmed during th e synthesis and provided a uniquely reactive functional group for cova lent modification of the peptide. The ketone and the sulfhydryl group of a cysteine residue elsewhere in the peptide were reacted simultaneo usly with two different biophysical probes, enabling the site-specific installation of a donor and acceptor pair for FRET in one step withou t the need for differential side chain protection. (C) 1998 Elsevier S cience Ltd. Atl rights reserved.