In Silico and Experimental Evidence for the Stabilization of rhEPO by Glycine, Glutamic Acid and Lysine.

The available literature indicates that amino acids can stabilize proteins. Our experimental data demonstrated that lysine and glutamic acid can stabilize recombinant human erythropoietin (rhEPO) at 40°C for at least 1 month, as measured by RP-UPLC. Studies with different excipient concentrations demonstrated optimal concentrations of these amino acids within 10-12 mM. The results suggest that a lower concentration of amino acids may not be sufficient to stabilize formulations, while a higher concentration of amino acids can lead lower stability. In silico studies highlighted the importance of the FA4G4S4 model in experimental glycosylation determination, particularly in glycoprotein analysis. We obtained insights into the interactions between the glycosylated ligands of rhEPO and amino acids, as well as their impact on protein behavior and stability. We observed different interactions between the amino acids glycine, glutamic acid, and lysine and the rhEPO protein using this model in docking experiments. They also made it easier to find specific interaction areas by analyzing ligand‒protein interaction fingerprints (PLIFs). This demonstrated how the ligands bind to the proteins or remain outside their vicinity. Furthermore, this study revealed specific places where ligands and rhEPO residues can interact, which helps us learn more about how they stabilize rhEPO.