Description Application L-Phenylalanine has been used in Fluo-4 Ca2+-assay in a study to demonstrate that G-protein coupled receptor 139 reference surrogate agonists 1a and 7c and L-phenylalanine share a common binding site.[4] It has also been used to spike blood samples to study the effect of dried blood spots on newborn screening.[5] Packaging 1 kg in poly bottle 100, 500 g in poly bottle Biochem/physiol Actions L-Phenylalanine is an essential aromatic amino acid.[1][2] It has a role in metabolism as it forms a starting point for many pathways.[3] This neutral amino acid is a precursor for tyrosine, epinephrine, dopamine and norepinephrine.[3][3]