(107d) Effect of Temperature and Shear on Protein Denaturation: Insights from Molecular Dynamics Simulations

Biologic drugs, or “biologics” are one of the fastest growing classes of FDA-approved therapeutics. These compounds are often fragile, and require conjugation to polymers for stabilization, with many proteins too ephemeral for therapeutic use. It is important that protein structure be preserved during conjugation and after delivery, as this dictates the efficacy of the drug. During storage and administration, proteins may unravel and lose their secondary structure due to various factors, such as fluctuations in temperature, solution pH, shearing forces, and other external stressors. Understanding the relationship between these stressors and protein structure is critical in developing effective strategies to prevent protein misfolding and aggregation. Despite the widespread use of PEG in therapeutics, the specific mechanisms by which polymers stabilize proteins remain largely unknown. A comprehensive understanding of the destabilizing effects triggered by external stressors and the subsequent stabilizing interactions of polymers is essential for designing more stable and effective protein therapeutics.

Protein-polymer conjugates typically lead to very low yields, and trial and error experimentation to determine structure-function relationships laborious, time intensive, and expensive. Computational simulations can overcome many of these limitations and connect protein structure to polymer chemistry over broad spatiotemporal scales. In this study, we employ all-atom molecular dynamics (MD) simulations to examine the unfolding process of lysozyme and insulin under high temperature and shear. By accessing the global structural change and local residue level details, we capture the unfolding process and identify residues that degrade first, which we refer to as the proteins' "weak links." Subsequently, we conjugate the proteins with PEG to understand how PEG helps preserve the protein structure at higher temperatures. Results from this work will help us design novel polymer conjugates customized to specific proteins for therapeutic applications.