title: The effect of protein PEGylation on physical stability in liquid formulation.
abstract: The presence of micron aggregates in protein formulations has recently attracted increased interest from regulatory authorities, industry, and academia because of the potential undesired side effects of their presence. In this study, we characterized the micron aggregate formation of hen egg-white lysozyme (Lyz) and its diPEGylated (5 kDa) analog as a result of typical handling stress conditions. Both proteins were subjected to mechanical stress in the absence and presence of silicone oil (SO), elevated temperatures, and freeze-thaw cycles. Flow imaging microscopy showed that PEGylated Lyz formed approximately half as many particles as Lyz, despite its lower apparent thermodynamic stability and more loose protein fold. Further characterization showed that the PEGylation led to a change from attractive to repulsive protein-protein interactions, which may partly explain the reduced particle formation. Surprisingly, the PEGylated Lyz adsorbed an order of magnitude faster onto SO, despite being much larger in size, as determined by small-angle X-ray scattering and dynamic light scattering measurements. Thus, PEGylation may significantly reduce, but not prevent, micron aggregate formation of a protein during typical handling stresses.
authors.affiliation: Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Louise Stenstrup
authors.initials: LS
authors.lastname: Holm
authors.forename: Aaron
authors.initials: A
authors.lastname: Mcumber
authors.forename: Jakob Ewald
authors.initials: JE
authors.lastname: Rasmussen
authors.forename: Marc
authors.initials: M
authors.lastname: Obiols-Rabasa
authors.forename: Peter W
authors.initials: PW
authors.lastname: Thulstrup
authors.forename: Marina R
authors.initials: MR
authors.lastname: Kasimova
authors.forename: Theodore W
authors.initials: TW
authors.lastname: Randolph
authors.forename: Marco
authors.initials: M
authors.lastname: van de Weert
mesh_terms: D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D008853:Microscopy; D011092:Polyethylene Glycols / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D011506:Proteins; D011092:Polyethylene Glycols
keywords: PEGylation; calorimetry (DSC); circular dichroism; light scattering; microflow imaging; physical stability; protein aggregation; proteins; silicone oil; small-angle X-ray scattering