Simantov R, Childers S R, Snyder S H
Eur J Pharmacol. 1978 Feb 1;47(3):319-31. doi: 10.1016/0014-2999(78)90240-6.
3H-Methionine enkephalin binds stereospecifically with high affinity to opiate receptors in rat brain membranes. Equilibrium experiments indicate two distinct dissociation constants with KD values of 1.8 and 5.8 nM respectively. 3H-Methionine enkephalin associates and dissociates from the opiate receptor with 8--10 fold slower kinetics than 3H-opiates. Though several opiates have similar affinities for sites labeled by 3H-methionine enkephalin, 3H-dihydromorphine and 3H-naloxone, some opiates such as morphine, dihydromorphine and oxymorphone are only one tenth as potent in competing for 3H-methionine enkephalin as for 3H-dihydromorphine and 3H-naloxone binding. As with other opiate agonists, 5--10 mM sodium selectively decreases the binding of 3H-methionine enkephalin. At 26 degrees C, 0.1--1.0 mM manganese but not magnesium or calcium increases the binding of 3H-methionine enkephalin, while at 0 degrees C manganese decreases the binding of methionine enkephalin.
3H-甲硫氨酸脑啡肽以高亲和力立体特异性地与大鼠脑膜中的阿片受体结合。平衡实验表明有两个不同的解离常数，KD值分别为1.8和5.8 nM。3H-甲硫氨酸脑啡肽与阿片受体的结合和解离动力学比3H-阿片类药物慢8 - 10倍。尽管几种阿片类药物对由3H-甲硫氨酸脑啡肽、3H-二氢吗啡和3H-纳洛酮标记的位点具有相似的亲和力，但一些阿片类药物，如吗啡、二氢吗啡和羟吗啡酮，在竞争3H-甲硫氨酸脑啡肽结合位点时的效力仅为竞争3H-二氢吗啡和3H-纳洛酮结合位点时的十分之一。与其他阿片类激动剂一样，5 - 10 mM的钠选择性降低3H-甲硫氨酸脑啡肽的结合。在26℃时，0.1 - 1.0 mM的锰而非镁或钙会增加3H-甲硫氨酸脑啡肽的结合，而在0℃时锰会降低甲硫氨酸脑啡肽的结合。
