IGM, Faculty of life Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
ChemMedChem. 2010 Apr 6;5(4):545-51. doi: 10.1002/cmdc.200900521.
The gut hormone PYY3-36 influences food intake and body weight via interaction with hypothalamic presynaptic Y2 receptors (Y2R). Novel Y2R-selective analogues of PYY3-36 are therefore potential drug candidates for the treatment of obesity. It has been hypothesized that PYY3-36 and possibly also the related PP-fold peptides, NPY and PP, bind to the membrane via their amphipathic alpha-helix prior to receptor interaction. The PYY3-36 amphipathic alpha-helix causes the peptide to associate with the membrane, making it essential for Y receptor potency as it potentially guides the C-terminal pentapeptide into the correct conformation for receptor activation. Based on this hypothesis, the importance of the amphipathic nature of PYY3-36, as well as the ability of amphipathic alpha-helices to interact in solution to form di- and tetramers, we redesigned the peptide architecture by addition of an amphipathic alpha-helix via the Lys 4 side chain of PYY3-36. Two different amphipathic sequences were introduced; first, PYY17-31, the native alpha-helix of PYY, and secondly, its retro counterpart, PYY31-17, which is also predicted to form an alpha-helix. Moreover, several different turn motifs between the branching point and the additional alpha-helix were tested. Several novel peptides with nanomolar Y2R binding affinities, as well as increased Y receptor selectivity, were identified. CD experiments showed the modifications to be well accepted, and an increase in mean ellipticity (ME) signifying an increased degree of alpha-helicity was observed. Receptor binding experiments indicated that the direction of the additional alpha-helix is less important, in contrast to the turn motifs, which greatly affect the Y1R binding and thus determine the Y1R activity. Conversely, the structure-activity relationships from in vivo data showed that the peptide containing the retro-sequence was inactive, even though the binding data demonstrated high affinity and selectivity. This demonstrates that radical redesign of peptide architecture can provide nanomolar binding with improved subtype selectivity and with in vivo efficacy.
肠激素 PYY3-36 通过与下丘脑突触前 Y2 受体（Y2R）相互作用影响食物摄入和体重。因此，新型的 PYY3-36 特异性 Y2R 类似物是治疗肥胖的潜在药物候选物。有人假设 PYY3-36 以及可能相关的 PP 折叠肽 NPY 和 PP 通过其两亲性α-螺旋与膜结合，然后再与受体相互作用。PYY3-36 的两亲性α-螺旋使肽与膜结合，对于 Y 受体的效力至关重要，因为它可能引导 C 端五肽进入正确的构象以激活受体。基于这一假设，PYY3-36 的两亲性以及α-螺旋在溶液中相互作用形成二聚体和四聚体的能力的重要性，我们通过添加亲α-螺旋通过 PYY3-36 的赖氨酸 4 侧链来重新设计肽结构。引入了两种不同的两亲性序列；首先，PYY17-31 是 PYY 的天然α-螺旋，其次，它的逆行对应物 PYY31-17 也被预测形成α-螺旋。此外，还测试了分支点和额外α-螺旋之间的几种不同的环化模体。鉴定出具有纳摩尔 Y2R 结合亲和力和增加的 Y 受体选择性的几种新型肽。CD 实验表明修饰被很好地接受，并且观察到平均椭圆度（ME）增加，表明α-螺旋度增加。受体结合实验表明，与显著影响 Y1R 结合从而决定 Y1R 活性的环化模体相比，额外α-螺旋的方向不那么重要。相反，来自体内数据的结构-活性关系表明，含有逆行序列的肽是无活性的，尽管结合数据表明具有高亲和力和选择性。这表明肽结构的彻底重新设计可以提供纳摩尔结合，改善亚型选择性，并具有体内功效。
