A Method for Rigorously Selective Capture and Simultaneous Fluorescent Labeling of N-Terminal Glycine Peptides
Hongxu Liu, Harnimarta Deol, Ava Raeisbahrami, Hadis Askari, Christopher D. Wight, Vincent M. Lynch, Eric V. Anslyn
Abstract
Although chemical methods for the selective derivatization of amino acid (AA) side chains in peptides and proteins are available, selective N-terminal labeling is challenging, especially for glycine, which has no side chain at the α-carbon position. We report here a double activation at glycine's α-methylene group that allows this AA to be differentiated from the other 19 AAs. A condensation reaction of dibenzoylmethane with glycine results in the formation of an imine, and subsequent tautomerization is followed by intramolecular cyclization, leading to the formation of a fluorescent pyrrole ring. Additionally, the approach exhibits compatibility with AAs possessing reactive side chains. Further, the method allows for selective pull-down assays of N-terminal glycine peptides from mixtures without prior knowledge of the N-terminal peptide distribution.