Design, Synthesis, Structural and Functional Characterization of Novel Melanocortin Agonists Based on the Cyclotide Kalata B1
Design, Synthesis, Structural and Functional Characterization of Novel Melanocortin Agonists Based on the Cyclotide Kalata B1
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DOI：
10.1074/jbc.m112.395442
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发表时间：
2012-11-23
影响因子：
4.8
通讯作者：
Craik, David J.
中科院分区：
文献类型：
--
作者：
Eliasen, Rasmus;Daly, Norelle L.;Craik, David J.
肥胖是一个日益重要的全球健康问题，目前缺乏治疗方案。黑素皮质素受体4(MC4R)是肥胖治疗的靶点，因为它的激活会触发食欲抑制并增加能量消耗。环类化合物已被认为是插入和稳定药用活性多肽的支架。在这项研究中，我们通过将His-Phe-Arg-Trp序列插入到环肽Kalata B1中合成MC4R激动剂来探索减胃肽的开发。研究了这些类似物折叠类似于Kalata B1但显示MC4R活性的能力。以C-端硫酸酯为主链，采用叔丁氧羰基多肽化学方法合成了4个多肽。经~1Hα核磁共振化学位移测定，其结构与卡拉塔B1相似。Kb1(GHFRWG；23-28)在MC4R处的K-I为29 nM，对该受体的选择性分别是MC1R和MC5R的107倍或314倍，并且没有检测到与MC3R的结合。该多肽对MC4R的亲和力高于内源性激动剂α-黑素细胞刺激激素，但对MC4R的亲和力较弱，激活MC4R的EC50为580 nM。综上所述，我们合成了Kalata B1的黑素皮质素类似物，它们保留了结构支架，并显示了受体结合和功能活性。Kb1(GHFRWG；23-28)对MC4R具有较强的选择性。这种化合物验证了环肽作为支架的使用，并有可能成为治疗肥胖症的新先导药物。
Obesity is an increasingly important global health problem that lacks current treatment options. The melanocortin receptor 4 (MC4R) is a target for obesity therapies because its activation triggers appetite suppression and increases energy expenditure. Cyclotides have been suggested as scaffolds for the insertion and stabilization of pharmaceutically active peptides. In this study, we explored the development of appetite-reducing peptides by synthesizing MC4R agonists based on the insertion of the His-Phe-Arg-Trp sequence into the cyclotide kalata B1. The ability of the analogues to fold similarly to kalata B1 but display MC4R activity were investigated. Four peptides were synthesized using t-butoxycarbonyl peptide chemistry with a C-terminal thioester to facilitate backbone cyclization. The structures of the peptides were found to be similar to kalata B1, evaluated by H alpha NMR chemical shifts. KB1(GHFRWG;23-28) had a K-i of 29 nM at the MC4R and was 107 or 314 times more selective over this receptor than MC1R or MC5R, respectively, and had no detectable binding to MC3R. The peptide had higher affinity for the MC4R than the endogenous agonist, alpha-melanocyte stimulation hormone, but it was less potent at the MC4R, with an EC50 of 580 nM for activation of the MC4R. In conclusion, we synthesized melanocortin analogues of kalata B1 that preserve the structural scaffold and display receptor binding and functional activity. KB1(GHFRWG;23-28) is potent and selective for the MC4R. This compound validates the use of cyclotides as scaffolds and has the potential to be a new lead for the treatment of obesity.