A Pyrrolysine Analogue for Protein Click Chemistry

Abstract

Ignoring the STOP sign: A pyrrolysine analogue bearing a terminal alkyne was site-specifically incorporated into recombinant calmodulin (CaM) through a UAG codon. The resulting protein was labeled with an azide-containing dye using a copper(I)-catalyzed click reaction. Subsequent application of an orthogonal cysteine tagging method yielded a CaM labeled with two distinct fluorophores that enabled its study by FRET spectroscopy.