Longo Edoardo, Santis Emiliana De, Hussain Rohanah, van der Walle Christopher F, Casas-Finet Jose, Uddin Shahid, Santos Ana Dos, Siligardi Giuliano
Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom.
Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom.
Int J Pharm. 2014 Sep 10;472(1-2):156-64. doi: 10.1016/j.ijpharm.2014.06.008. Epub 2014 Jun 10.
Peptides are ideal drug candidates due to their potency and specificity, but suffer from a short half-life and low membrane permeability. Acylation can overcome these limitations but the consequences to stability under different formulation conditions and stresses are largely unreported. Using synchrotron radiation circular dichroism (SRCD), we show that palmitoylation of a 28 amino acid peptide hormone (pI 9.82) induced a structural transition from 310-helix to α-helix, irrespective of buffer type and pH investigated (5.5-8.0) when compared to the non acylated analogues. These conformational preferences were retained in the presence of non-ionic micelles but not anionic micelles, which induced an α-helical structure for all peptides. Palmitoylation promoted an irreversible peptide denaturation under thermal stress at pH ≥ 6.5 and increased the propensity for loss of helical structure under high photon flux (here used as a novel accelerated photostability test). The presence of either ionic or non-ionic micelles did not recover these conformational changes over the same irradiation period. These results demonstrate that acylation can change peptide conformation and decrease thermal-/photo-stability, with important consequences for drug-development strategies.
由于其效力和特异性，肽是理想的药物候选物，但存在半衰期短和膜通透性低的问题。酰化可以克服这些限制，但在不同制剂条件和应力下对稳定性的影响在很大程度上尚未见报道。利用同步辐射圆二色性（SRCD），我们发现，与未酰化类似物相比，一种28个氨基酸的肽激素（pI 9.82）的棕榈酰化诱导了从310螺旋到α螺旋的结构转变，无论所研究的缓冲液类型和pH值（5.5 - 8.0）如何。在存在非离子胶束的情况下，这些构象偏好得以保留，但在阴离子胶束存在时则不然，阴离子胶束会诱导所有肽形成α螺旋结构。在pH≥6.5的热应力下，棕榈酰化促进了肽的不可逆变性，并增加了在高光子通量下（此处用作一种新型加速光稳定性测试）螺旋结构丧失的倾向。在相同的辐照时间内，离子或非离子胶束的存在都无法恢复这些构象变化。这些结果表明，酰化可以改变肽的构象并降低热稳定性/光稳定性，这对药物开发策略具有重要影响。
