Fischer Jan-Patrick, Schönauer Ria, Els-Heindl Sylvia, Bierer Donald, Koebberling Johannes, Riedl Bernd, Beck-Sickinger Annette G
Institut für Biochemie, Fakultät für Lebenswissenschaften, Universität Leipzig, Leipzig, Germany.
Bayer AG, Aprather Weg 18A, Wuppertal, Germany.
J Pept Sci. 2019 Mar;25(3):e3147. doi: 10.1002/psc.3147. Epub 2019 Jan 24.
Adrenomedullin (ADM) is a vasoactive peptide hormone of 52 amino acids and belongs to the calcitonin peptide superfamily. Its vasodilative effects are mediated by the interaction with the calcitonin receptor-like receptor (CLR), a class B G protein-coupled receptor (GPCR), associated with the receptor activity modifying protein 2 (RAMP2) and functionally described as AM-1 receptor (AM R). A disulfide-bonded ring structure consisting of six amino acids between Cys and Cys has been shown to be a key motif for receptor activation. However, the specific structural requirements remain to be elucidated. To investigate the influence of ring size and position of additional functional groups that replace the native disulfide bond, we generated ADM analogs containing thioether, thioacetal, alkane, and lactam bonds between amino acids 16 and 21 by Fmoc/t-Bu solid phase peptide synthesis. Activity studies of the ADM disulfide bond mimetics (DSBM) revealed a strong impact of structural parameters. Interestingly, an increased ring size was tolerated but the activity of lactam-based mimetics depended on its position within the bridging structure. Furthermore, we found the thioacetal as well as the thioether-based mimetics to be well accepted with full AM R activity. While a reduced selectivity over the calcitonin gene-related peptide receptor (CGRPR) was observed for the thioethers, the thioacetal was able to retain a wild-type-like selectivity profile. The carbon analog in contrast displayed weak antagonistic properties. These results provide insight into the structural requirements for AM R activation as well as new possibilities for the development of metabolically stabilized analogs for therapeutic applications of ADM.
肾上腺髓质素（ADM）是一种由52个氨基酸组成的血管活性肽激素，属于降钙素肽超家族。其血管舒张作用是通过与降钙素受体样受体（CLR）相互作用介导的，CLR是一种B类G蛋白偶联受体（GPCR），与受体活性修饰蛋白2（RAMP2）相关，功能上被描述为AM-1受体（AM R）。已证明由半胱氨酸和半胱氨酸之间的六个氨基酸组成的二硫键环结构是受体激活的关键基序。然而，具体的结构要求仍有待阐明。为了研究环大小和取代天然二硫键的其他官能团位置的影响，我们通过Fmoc/t-Bu固相肽合成法生成了在氨基酸16和21之间含有硫醚、硫缩醛、烷烃和内酰胺键的ADM类似物。ADM二硫键模拟物（DSBM）的活性研究揭示了结构参数的强烈影响。有趣的是，环大小增加是可以接受的，但基于内酰胺的模拟物的活性取决于其在桥接结构中的位置。此外，我们发现硫缩醛以及基于硫醚的模拟物具有良好的接受度且具有完整的AM R活性。虽然观察到硫醚对降钙素基因相关肽受体（CGRPR）的选择性降低，但硫缩醛能够保留野生型样的选择性谱。相比之下，碳类似物表现出较弱的拮抗特性。这些结果为AM R激活的结构要求提供了见解，并为开发用于ADM治疗应用的代谢稳定类似物提供了新的可能性。
