Scientists first discovered the way to induce this "selective uptake" using p-boronophenylalanine (BPA). BPA is a boron-containing compound with a phenylalanine structure.

Yoshiyuki Tanaka, Makoto Matsuoka, Naoki Yamanoto, Yuko Ohashi, Yuriko Kano-Murakami, Yoshihiro Ozeki, Structure and Characterization of a cDNA Clone for Phenylalanine Ammonia-Lyase from Cut-Injured ...

Types There are three different types of phenylalanine: L-phenylalanine, D-phenylalanine, and DL-phenylalanine. Each one has a slightly different chemical structure.