L-BCN-amino Acid Synthesis And Its Application In Diels-Alder Reaction

The study of biomolecules in their native environments is a challenge because the vast complexity of biological systems. Bioorthogonal technologies have been developed to overcome these obstacles and the selective modification of biological molecules in living organisms is possible. Tetrazines can react rapidly and specifically with strained alkenes via Diels-Alder cycloaddition to form stable adducts. Due to its extremely fast reaction rate and mild reaction conditions, bioorthogonal reactions has been widely used in the field of biochemistry. And genetically encoding non-canonical amino acid that based on IED-DA cycloaddition reactions is an attractive strategy to achieve rapid and site-specific labeling of proteins. A set of dienophiles-containing amino acids has been synthesized and incorporated into proteins. However, many synthetic non-canonical amino acids were connected by a ligand or a linker between these functional tags and an amino acid group, which are relatively bulky and difficult to be moved to multiple locations within peptides. In this paper, we used the method of the Strecker amino acid synthesis, and first synthesized the BCN group modified unnatural amino acids, and used the kidney acyltransferase to obtain L-type BCN amino acid successfully. The L-BCN amino acid can be used for labeling of cancer cells (tag labeling with tetrazine fluorescent molecules) and be used as amino acid analogues in modification of peptides. In addition, this article first used L-BCN amino acid as a probe molecule to label living cells.