Chang K J, Lillian A, Hazum E, Cuatrecasas P, Chang J K
Science. 1981 Apr 3;212(4490):75-7. doi: 10.1126/science.6259732.
The synthetic peptide NH2-Tyr-Pro-Phe-Pro-CONH2 (morphiceptin), which is the amide of a fragment of the milk protein beta-casein, has morphinelike activities and is highly specific for morphine (mu) receptors but not for enkephalin (delta) receptors. It is as active as morphine in the guinea pig ileum but much less active in the mouse and rat vas deferens. The discovery of this specific morphine receptor ligand substantiates the hypothesis of multiple opiate receptors. The ligand, which may be of physiological significance since a very similar, or identical, activity can be detected in enzymatic digests of beta-casein, may prove useful for further investigation of the functions of opiate receptor subtypes.
合成肽NH2-Tyr-Pro-Phe-Pro-CONH2（吗啡七肽）是乳蛋白β-酪蛋白片段的酰胺，具有吗啡样活性，对吗啡（μ）受体具有高度特异性，而对脑啡肽（δ）受体不具有特异性。它在豚鼠回肠中的活性与吗啡相当，但在小鼠和大鼠输精管中的活性要低得多。这种特异性吗啡受体配体的发现证实了多种阿片受体的假说。该配体可能具有生理意义，因为在β-酪蛋白的酶消化物中可检测到非常相似或相同的活性，它可能对进一步研究阿片受体亚型的功能有用。
