DL-PHENYLALNINE, or DLPA, is a 50/50 mixture of the D-and L- form of the amino acid phen-ylalanine (phenylalanine is one of the few amino that can be utilized in its D-form). Researchers believe that D-phenylalanine (DPA) inhibits the action of an enzyme that break down endorphins and enkephalins. These protein bind to opiate receptor sites in the brain, thereby influ-encing the perception of discomfort.. By obstructing the action of this enzyme DPA may extend the life of endrophins and enkepha