Side‐chain thioamides as fluorescence quenching probes
D. Miklos Robkis, Eileen M. Hoang, Pengse Po, Carol Deutsch, E. James Petersson
Abstract
Abstract Thioamides, single atom oxygen‐to‐sulfur substitutions of canonical amide bonds, can be valuable probes for protein folding and protease studies. Here, we investigate the fluorescence quenching properties of thioamides incorporated into the side‐chains of amino acids. We synthesize and incorporate Fmoc‐protected, solid‐phase peptide synthesis building blocks for introducing N ε ‐thioacetyl‐lysine and γ ‐thioasparagine. Using rigid model peptides, we demonstrate the distance‐dependent fluorescence quenching of these thioamides. Furthermore, we describe attempts to incorporate of N ε ‐thioacetyl‐lysine into proteins expressed in Escherichia coli using amber codon suppression.