L-ANAP is a fluorescent unnatural amino acid which enables the fluorescent labeling of any protein by changing a single codon to incorporate this amino acid at any permissive site. It has utility in FRET assays and biophysical studies. It has been successfully incorporated into proteins in Xenopus oocytes, yeast (Lee, 2009), and mammalian cells (CHO, HEK293) (Chatterjee, 2013). It is ideal for protein conformation and post-translational modification experiments. Additionally, L-ANAP exhibits a spectral shift in emission dependent upon surrounding polarity making it uniquely capable of indicating environmental changes.L-ANAP has an excitation maxima of 360nm, emission maxima 490nm in water with shifts as far as 420nm. Extinction coefficient 17,500 cm-1M-1. Non-toxic in mammalian cells at concentrations as high as 500 uM (Chatterjee, 2013).The L-ANAP-OMe variant (ASIS-0146) has increased solubility compared to the related product, L-ANAP TFA (ASIS-0014).Incorporation of L-ANAP requires the expression of a modified tRNA/synthetase pair derived from E. coli (Chatterjee, 2013). A mammalian expression plasmid containing the amber suppressor tRNA and the synthetase AnapRS is available from Addgene (www.addgene.org/48696).