Opioid activity of delta O-endorphin in the guinea pig ileum.
The oligopeptides beta- and delta O-endorphin were isolated from porcine and bovine pituitary respectively. Their opiate activity was determined in the guinea pig ileum and compared to that of the pentapeptide methionine-enkephalin and morphine. The rank order of opioid activity was found to be: morphine greater than beta-endorphin = Met-enkephalin greater than delta O-Endorphin which lacks the four C-terminal amino acids of beta-endorphin displayed 60% of the activity of beta-endorphin. These results indicate, that C-terminal amino acids contribute little to the affinity of beta-endorphin for opiate receptors in the guinea pig ileum.
D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D004723:Endorphins / Q000302:isolation & purification / Q000378:metabolism*; D004745:Enkephalins / Q000378:metabolism; D006168:Guinea Pigs; D007082:Ileum / Q000378:metabolism*; D007700:Kinetics; D009020:Morphine / Q000378:metabolism; D010902:Pituitary Gland / Q000032:analysis; D011957:Receptors, Opioid / Q000378:metabolism*; D013552:Swine
D004723:Endorphins; D004745:Enkephalins; D011957:Receptors, Opioid; D009020:Morphine