Effects of Lyophilization, Vacuum Drying, and Microglassification on Two Model Proteins Assessed at the Residue Level...

We explore the effects of drying methods on residue-level protein structure using Liquid-Observed Vapor Exchange Nuclear Magnetic Resonance spectroscopy (LOVE NMR) data from two proteins, the B1 domain of streptococcal protein G and the enzyme adenylate kinase (AdK) from Escherichia coli. The data show that both vacuum drying and microglassification are more protective than lyophilization. Assessing the effects on AdK activity leads to the same conclusion. Another important conclusion comes from comparing solution stability to dry-state protection. Namely, regions exposed only upon complete unfolding in solution are those that are most protected in the dry state, an observation that could be made because of the residue-level resolution of LOVE NMR. The results will help guide the discovery and optimization of new excipients for solid formulations.