N-ε-propargyloxycarbonyl-L-lysine (H-L-Lys(Poc)-OH) is a lysine-based unnatural amino acid (UAA). N-ε-propargyloxycarbonyl-L-lysine is widely used for bio-conjugation of fluorescent probes in diverse organisms from E. coli to mammalian cells even in animals[2].In Vitro: Labeling of N-ε-propargyloxycarbonyl-L-lysine (H-L-Lys(Poc)-OH)-carrying cellular proteins, such as Sec61β, Htt74Q and the histone H3 variant H3.3, with a sensitive Raman tag by click chemistry for molecular hyperspectral SRS imaging.