Conformationally restricted competitive antagonists of human/rat corticotropin-releasing factor.
Conformationally restricted competitive antagonists of human/rat corticotropin-releasing factor.
复制标题
人/大鼠促肾上腺皮质激素释放因子的构象限制性竞争性拮抗剂。
DOI：
10.1021/jm00036a010
复制
发表时间：
1994
影响因子：
7.3
通讯作者：
Rivier,J
中科院分区：
文献类型：
--
作者：
Miranda,A;Koerber,SC;Gulyas,J;Lahrichi,SL;Craig,AG;Corrigan,A;Hagler,A;Rivier,C;Vale,W;Rivier,J
促肾上腺皮质激素释放因子（CRF）是一种41肽酰胺，刺激ACTH的释放（Vale等）。科学1981,213,1394)。CRF在与其垂体受体结合后被假定为a-螺旋构象（Hernandez等）。医学化学杂志，1993,36,2860)。我们在设计一系列有限的环状类似物时利用了这一假设，并考虑了侧链缺失的影响（丙氨酸扫描，Kornreich等人）。J. Med. Chem. 1992,35,1870)以及手性的变化(Rivier et al.；J. Med. Chem. 1993, 36, 2851)，其基本原理是，结合所必需的侧链也可以被侧链桥取代。特别是，我们使用计算机建模来预测可能的侧链桥接机会，并通过将生物学结果与CD光谱得出的结果相关联来评估这种替代的效果。我们采用固相法在MBHA树脂上合成了38种单环肽酰胺，它们是人/鼠/ crf的竞争性拮抗剂。制备型反相高效液相色谱法纯化后，采用反相高效液相色谱法和毛细管区带电泳对肽段进行分析，并用质谱和氨基酸分析对肽段进行表征。我们测试了CRF拮抗剂对CRF诱导的大鼠垂体前叶细胞释放ACTH的干扰能力。在大多数情况下，其中一个桥头位于可以容忍d -残基取代的位置（即位置12和20）。很明显，仔细优化桥的长度和手性是至关重要的。在合成和测试的38个类似物中，只有两个，{cyclo (20-23)[DPhe12, Glu20, Lys23, Nle21> 38] h/rCRFi2_41}和cyclo-(20-23)[DPhe12, Glu20, Orn23, Nle21-38] h/rCRFi2_4i}，被发现比母体化合物[DPhe12， Nle21, 38] h/rCRFi2_4i}更有效（分别为3倍和2倍）。属于两个不同科的六种类似物被发现效力为标准效力的一半，18种效力为标准效力的2-20%，其他的效力明显低于标准效力。所有类似物在50% TFE （TFE浓度可诱导接近最大螺旋度[DPhe12， Nle21, 38] h/rCRFi2-4i）下的CD结果表明，虽然螺旋度可能是识别CRF类似物的重要因素，但通过光谱反卷积确定的螺旋度百分比与体外生物活性之间几乎没有相关性。
Corticotropin releasing factor (CRF) is a 41-peptide amide which stimulates the release of ACTH (Vale et al. Science 1981, 213, 1394). CRF has been postulated to assume an a-helical conformation upon binding to its pituitary receptor (Hernandez et al. J. Med. Chem. 1993, 36, 2860). We have exploited this hypothesis in the design of a limited series of cyclic analogues and have taken into consideration the effects of side-chain deletion (Alanine scan, Kornreich et al. J. Med. Chem. 1992, 35, 1870) as well as of changes in chirality (Rivier et al. J. Med. Chem. 1993, 36, 2851), with the rationale that side chains necessary for binding could also be replaced by side-chain bridges. In particular, we have used computer modeling to predict likely side chain bridging opportunities and evaluated the effects of such replacements by correlating biological results with those derived from CD spectroscopy. We have synthesized 38 monocyclic peptide amides, competitive antagonists of human/ratCRF, using solid-phase methodology on MBHA resin. After purification by preparative RP-HPLC, the peptides were analyzed byRP-HPLC and capillary zone electrophoresis and characterized by mass spectroscopy and amino acid analysis. CRF antagonists were tested for their ability to interfere with CRF-induced release of ACTH by rat anterior pituitary cells. In most cases, one of the bridge heads was located at a position where substitution by a D-residue was tolerated (ie, positions 12 and 20). It has become clear that careful optimization of bridge length and chirality is critical. This is best exemplified by the fact that out of the 38 analogues that were synthesized and tested, only two,{cyclo (20-23)[DPhe12, Glu20, Lys23, Nle21> 38] h/rCRFi2_41 and cyclo-(20-23)[DPhe12, Glu20, Orn23, Nle21-38] h/rCRFi2_4i}, were found to be more potent (3 and 2 times, respectively) than [DPhe12, Nle21, 38] h/rCRFi2^ i, the parent compound. Six analogues belonging to two different families were found to be half as potent as the standard, 18 had 2-20% of the potency of the standard, and the others were significantly less potent. CD results of all analogues in 50% TFE (a concentration of TFE that induced nearly maximumhelicity of [DPhe12, Nle21, 38] h/rCRFi2-4i) suggest that while helicity may be an important factor for CRF analogue recognition, little correlation is found between percent helicity as determined by spectral deconvolution and biological activity in vitro.