Effect of Linker’s Length and Sequence on the Structure and Stability of mGLP-1-DARPin Fusion Protein for Treatment of Type 2 Diabetes: A Computational Study

Abstract

Background: Glucagon-like peptide-1 (GLP-1) is a promising peptide for the treatment of type 2 diabetes mellitus. However, the potential for therapeutic use of native GLP-1 is limited due to its extremely short half-life (a few minutes). In this research, a modified protease-resistant glucagon-like peptide-1 (mGLP-1) and a human serum albumin-binding DARPin connected by flexible and helical rigid linkers were designed to increase the half-life of this therapeutic peptide. Materials and Methods: In this study, the primary and secondary structures of designed fusion proteins were computationally studied, and some of their properties were predicted. The 3D model of the fusion proteins was created using the trRosetta server, and molecular docking between the fusion proteins and their respective receptors was conducted in the ClusPro server. Results: The results showed that the helical rigid linker (EAAAK)3 produced the best structure and stability for the designed fusion protein, and the fusion protein could preserve the original structure of the GLP-1 and DARPin molecules. The results of protein-ligand docking confirmed the interaction of fusion proteins with respectable receptors. Conclusion: When developing new fusion proteins, displaying and validating the domains of the designed structure is essential for comparing the efficiency and functionality with its natural homolog. The results of this study demonstrated that the mGLP-1-(EAAAK)3-DARPin fusion protein could be used in stability engineering to increase the half-life of the GLP-1 peptide drug in combination with HSA-binding DARPin.