p-Nitrophenylalanine (Phe(p-NO2)) was incorporated in place of Phe4 of [d-Ala2, Leu(CH2S-Npys)5]enkephalin. In the rat brain receptor binding assay, Npys-containing Phe(p-NO2)4- and Phe4-enkephalins exhibited almost unchanged affinities for μ receptors (IC50 = 16—21 nM). However, when the membrane was incubated with each analog, Phe(p-NO2)4-enkephalin (EC50 = 6.90 nM) could label the μ receptors about three times more effectively than Phe4-enkephalin.
对
硝基苯丙
氨酸(Phe(p-
NO2))取代了[d-Ala2, Leu(
CH2S-Npys)5]
脑啡肽的Phe4。在大鼠脑受体结合实验中,含Npys的Phe(p- )4-和Phe4-
脑啡肽对μ受体的亲和力几乎不变(IC50 = 16—21 nM)。然而,当膜与每个类似物孵育时,Phe(p- )4-
脑啡肽(
EC50 = 6.90 nM)标记μ受体的效率比Phe4-
脑啡肽高约三倍。