Biocatalytic Synthesis of an Unnatural Fluorescent Amino Acid

The long-term goal of this project is to chemically synthesize an unnatural fluorescent amino acid, 3-[7-nitro-2,1,3-benzoxadiazol-4-yl]-L-alanine, that can later allow researchers to visualize a single “glow-in-the-dark” protein in an otherwise transparent living cell. In addition to our attempted organic synthesis, here we report a biocatalytic synthesis. Specifically, we plan to use the enzyme glutathione S-transferase from the cyanobacterium T. elongatus to catalyze the key nucleophilic aromatic substitution reaction. As part of this effort, we are planning a new synthetic route to the non-natural amino acid, beta-amino alanine. In sum, we hope to synthesize these two unnatural amino acids in a more time- and cost-efficient manner