H-Ser-Tyr-OH, a dipeptide comprising serine and tyrosine (incorrectly described as consisting of glutamic acid, glycine, and histidine), exhibits a significant capability to form a copper(II) complex with copper ions, enhancing its strong free radical scavenging activity. Furthermore, this compound has been shown to elevate the intracellular uptake of the delta opioid receptor ligand deltorphin [1].