title: Influence of PEGylation with linear and branched PEG chains on the adsorption of glucagon to hydrophobic surfaces.
abstract: PEGylation has proven useful for prolonging the plasma half lives of proteins, and since approval of the first PEGylated protein drug product by the FDA in 1990, several PEGylated protein drug products have been marketed. However, the influence of PEGylation on the behavior of proteins at interfaces is only poorly understood. The aim of this work was to study the effect of PEGylation on the adsorption of glucagon from aqueous solution to a hydrophobic surface and to compare the effects of PEGylation with a linear and a branched PEG chain, respectively. The 3483 Da peptide glucagon was PEGylated with a 2.2 kDa linear and a branched PEG chain, respectively, and the adsorption behaviors of the three proteins were compared using isothermal titration calorimetry, fixed-angle optical reflectometry and total internal reflection fluorescence. PEGylation decreased the number of glucagon molecules adsorbing per unit surface area and increased the initial adsorption rate of glucagon. Furthermore, the results indicated that the orientation and/or structural changes of glucagon upon adsorption were affected by the PEGylation. Finally, from the isothermal titration calorimetry and the reflectometry data, it was observed that the architecture of the PEG chains had an influence on the observed heat flow upon adsorption as well as on the initial rate of adsorption, respectively.
authors.affiliation: Department of Pharmaceutics and Analytical Chemistry, University of Copenhagen, Copenhagen, Denmark. cp@farma.ku.dk
authors.forename: Charlotte
authors.initials: C
authors.lastname: Pinholt
authors.forename: Jens Thostrup
authors.initials: JT
authors.lastname: Bukrinsky
authors.forename: Susanne
authors.initials: S
authors.lastname: Hostrup
authors.forename: Sven
authors.initials: S
authors.lastname: Frokjaer
authors.forename: Willem
authors.initials: W
authors.lastname: Norde
authors.forename: Lene
authors.initials: L
authors.lastname: Jorgensen
mesh_terms: D000327:Adsorption; D005934:Glucagon / Q000031:analogs & derivatives* / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D011487:Protein Conformation; D012821:Silanes / Q000737:chemistry; D013499:Surface Properties
chemical_list: D011108:Polymers; D011137:Polystyrenes; D012821:Silanes; D011092:Polyethylene Glycols; D005934:Glucagon