Leu-enkephalins compete with and mimic the effects of opiate drugs. They play a role in a number of physiologic functions, including pain perception and responses to stress (By similarity). . Dynorphin peptides differentially regulate the kappa opioid receptor. Dynorphin A(1-13) has a typical opioid activity, it is 700 times more potent than Leu-enkephalin (By similarity). . Leumorphin has a typical opioid activity and may have anti- apoptotic effect. . This is the function of PDYN (prodynorphin, Ensembl gene identifier ENSG00000101327).