Atomistic insight towards the impact of polymer architecture and grafting density on structure-dynamics of PEGylated bovine serum albumin and their applications.

Abstract

Macromolecules such as proteins conjugated to polyethylene glycol (PEG) have been employed in therapeutic drug applications, and recent research has emphasized the potential of varying polymer architectures and conjugation strategies to achieve improved efficacy. In this study, we performed atomistic molecular dynamics simulations of bovine serum albumin (BSA) conjugated to 5 kDa PEG polymers in an array of schemes, including varied numbers of attached chains, grafting density, and nonlinear architectures. Nonlinear architectures included U-shaped PEG, Y-shaped PEG, and poly(oligoethylene glycol methacrylate) (POEGMA). Buried surface area calculations and polymer volume map analyses revealed that volume exclusion behaviors of the high grafting density conjugate promoted additional protein-polymer interactions when compared to simply increasing numbers of conjugated chains uniformly across the protein surface. Investigation of nonlinear polymer architectures showed that stable polymer-lysine loop-like conformations seen in previous conjugate designs were more variable in prevalence, especially in POEGMA, which contained short oligomer PEG chains. The findings of this comprehensive study of alternate PEGylation schemes of BSA provide critical insight into molecular patterns of interaction within bioconjugates and highlight their importance in the future of controlled modification of conjugate system parameters.