Sartania N, Szatmári I, Orosz G, Rónai A Z, Medzihradszky K, Borsodi A, Benyhe S
Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged.
Eur J Pharmacol. 1999 Jun 4;373(2-3):241-9. doi: 10.1016/s0014-2999(99)00248-4.
[Met5]enkephalin-Arg-Phe (Tyr-Gly-Gly-Phe-Met-Arg-Phe) was modified with the methyl esther of melphalan (Mel; 4-bis(2-chloroethyl)amino-L-phenylalanine) and the resulting compounds were studied for their opioid binding properties in guinea pig and rat brain membranes. Three new peptides, with a substitution of a single amino acid, were synthesized (Mel-Gly-Gly-Phe-Met-Arg-Phe, Tyr-Gly-Gly-Mel-Met-Arg-Phe and Tyr-Gly-Gly-Phe-Met-Arg-Mel). In the rat brain, none of these ligands displayed any type specificity, whereas in guinea pig brain membranes the C-terminally modified peptide, Tyr-Gly-Gly-Phe-Met-Arg-Mel ([Mel7]peptide), displayed a kappa-binding profile and was a weak kappa-opioid-receptor agonist in isolated guinea pig ileum. The effect of sodium ions on [Mel7]peptide competition against [3H]naloxone binding indicated a weak agonist nature of the compound. When guinea pig brain membranes were preincubated with 1-10 microM of [Mel7]peptide, an apparently irreversible inhibition of [3H]naloxone ligand binding was observed. These results suggest that the heptapeptide containing melphalan at the C-terminus can be used as a relatively high-affinity irreversible label for the kappa-opioid receptor.
[Met5]脑啡肽 - 精氨酸 - 苯丙氨酸（酪氨酸 - 甘氨酸 - 甘氨酸 - 苯丙氨酸 - 甲硫氨酸 - 精氨酸 - 苯丙氨酸）用美法仑（Mel；4 - 双（2 - 氯乙基）氨基 - L - 苯丙氨酸）的甲酯进行修饰，并对所得化合物在豚鼠和大鼠脑膜中的阿片样物质结合特性进行了研究。合成了三种新的单氨基酸取代肽（Mel - 甘氨酸 - 甘氨酸 - 苯丙氨酸 - 甲硫氨酸 - 精氨酸 - 苯丙氨酸、酪氨酸 - 甘氨酸 - 甘氨酸 - Mel - 甲硫氨酸 - 精氨酸 - 苯丙氨酸和酪氨酸 - 甘氨酸 - 甘氨酸 - 苯丙氨酸 - 甲硫氨酸 - 精氨酸 - Mel）。在大鼠脑中，这些配体均未表现出任何类型特异性，而在豚鼠脑膜中，C末端修饰的肽酪氨酸 - 甘氨酸 - 甘氨酸 - 苯丙氨酸 - 甲硫氨酸 - 精氨酸 - Mel（[Mel7]肽）呈现出κ结合特征，并且在分离的豚鼠回肠中是一种弱κ阿片受体激动剂。钠离子对[Mel7]肽与[³H]纳洛酮结合竞争的影响表明该化合物具有弱激动剂性质。当豚鼠脑膜与1 - 10μM的[Mel7]肽预孵育时，观察到对[³H]纳洛酮配体结合的明显不可逆抑制。这些结果表明，在C末端含有美法仑的七肽可用作κ阿片受体的相对高亲和力不可逆标记物。
