Peptide Helix-Y12 as Potential Effector for Peroxisome Proliferator-Activated Receptors

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors involved in the regulation of lipids and glucose metabolism, and immune response. Therefore, they have been considered pharmacological targets for treating metabolic diseases, such as dyslipidemia, atherosclerosis, and non-alcoholic fatty liver disease. However, the available synthetic ligands of PPARs have mild to significant side effects, generating the necessity to identify new molecules that are selective PPAR ligands with specific biological responses. This study aimed to evaluate some components of the atheroprotective and hepatoprotective HB-ATV-8 nanoparticles [the amphipathic peptide Helix-Y-12, thermozeaxanthin, thermozeaxanthin-13, thermozeaxanthin-15, and a set of glycolipids], as possible ligands of PPARs through blind molecular docking. According to the change in free energy upon protein-ligand binding, increment G(b), thermozeaxanthins show a more favorable interaction with PPARs, followed by Helix-Y-12. Moreover, Helix-Y-12 interacts with most parts of the Y-shaped ligand-binding domain (LBD), surrounding helix 3 of PPARs, and reaching helix 12 of PPAR alpha and PPAR gamma. As previously reported for other ligands, Tyr314 and Tyr464 of PPAR alpha interact with Helix-Y-12 through hydrogen bonds. Several PPAR alpha's amino acids are involved in the ligand binding by hydrophobic interactions. Furthermore, we identified additional PPARs' amino acids interacting with Helix-Y-12 through hydrogen bonds still not reported for known ligands. Our results show that, from the studied ligand set, the Helix-Y-12 peptide and Tzeaxs have the most significant probability of binding to the PPARs' LBD, suggesting novel ligands for PPARs.