L-ANAP hydrochloride is a fluorescent unnatural amino acid (Uaa) that is both genetically encodable and polarity-sensitive.

L-ANAP, a fluorescent noncanonical amino acid, serves as a specific label for fluorescence [1]. As a genetically encodable, polarity-sensitive fluorescent unnatural amino acid (Uaa), L-ANAP joins counterparts such as L-dansylalanine and L-(7-hydroxycoumrin-4-yl)ethylglycine in its utility for molecular and cellular biology, potentially complementing and enhancing conventional fluorescent proteins (FPs) [2].